Galaxy Zoo Forum

The objects => Object of the Day => : JeanTate May 16, 2012, 12:03:26 AM

: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 16, 2012, 12:03:26 AM
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.8875&dec=69.065&scale=0.2&width=200&height=200)

Strange sort of thing to start an OOTD with, don't you think? Is it, perhaps, some sort of color chart? Let's expand the picture to 600x600:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.8875&dec=69.065&scale=0.2&width=600&height=600)

Hmm. Not a color chart; what if we zoom out a bit, five-fold in fact?

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.8875&dec=69.065&scale=1.0&width=600&height=600)

Ah, that's better; this is obviously a giant spiral galaxy, a rather beautiful one. Zooming out, by another factor of five:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.8875&dec=69.065&scale=5.0&width=600&height=600)

Some of you probably now recognize it, it's M81, i.e. number 81 in Messier's list of fuzzies that he compiled in order to avoid mistaking them for comets. And one day there'll be a full entry on it in Messier catalogue LIST (http://www.galaxyzooforum.org/index.php?topic=280086.msg601635#msg601635), a zooite forum project.

Here's another rather beautiful, classical spiral, as seen by the Hubble Space Telescope (from this OOTD (http://www.galaxyzooforum.org/index.php?topic=278516.0)):

(http://zoo-hst.s3.amazonaws.com/12024856.jpg)

And here it is, as seen by the SDSS telescope, at the same scale as the first image of M81 (the orientation is different from that of the Hubble image):

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=214.59292&dec=52.71833&scale=0.2&width=424&height=424)

 :o :o Yep, that beautiful spiral is the small, fuzzy blob in the center of this SDSS image. The two galaxies look so different in large part because they are at very different distances from us: M81's is 3.6 Mpc (http://arxiv.org/abs/1103.0549) (which is derived using M81's estimated distance modulus (http://astro.unl.edu/naap/distance/distance_modulus.html); 3.6 Mpc is 11.7 million light-years); SDSS J141822.30+524306.1's is 1.186 Gpc (derived using the Hubble redshift-distance relationship - the galaxy's redshift is 0.2388 - and Ned Wright's Cosmology Calculator (http://www.astro.ucla.edu/~wright/CosmoCalc.html) with generally accepted values for the various cosmological parameters[1]; that's 3.87 billion light-years).

NGC3314 wrote an excellent OOTD on spirals, and how there's no way to tell, from their appearance alone, how big they actually are (or were): Friday 23rd October 2009: Spirals big and small (http://www.galaxyzooforum.org/index.php?topic=276492.0). In that he explains that M81 is, in fact, pretty wimpy in the big spiral stakes; two of the biggest, in his OOTD (and in the SDSS footprint) are M104 (the Sombrero galaxy (http://hubblesite.org/newscenter/archive/releases/2003/28/image/a/), z=0.0034) and NGC 309 (http://adsabs.harvard.edu/abs/2007sptz.prop40175F) (z=0.0178). Here are the SDSS images of these two - M104 first - at the same scale as the last of the M81 images:

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=189.99764&dec=-11.62214&scale=5.0&width=600&height=600)

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=14.1777521&dec=-9.91386599&scale=5.0&width=600&height=600)

Time for a history-of-astronomy trivia quiz question: you have all heard, I'm sure, of the fact that some people - even some astronomers - do not accept that the Hubble distance-redshift relationship holds for all galaxies (once you take account of some small, local variations); what role did M81 and NGC 309 play, as evidence against this relationship? For an extra bonus point, what is the name of the astronomer made the connection? For two bonus points, what's wrong with this evidence (that involving M81 and NGC 309)? I'll post answers later.  :D  :-*

Now for two rather boring-looking galaxies; the first I posted in last week's OOTD (http://www.galaxyzooforum.org/index.php?topic=280120.0), the second has not been posted in this forum before (as far as I can tell):

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.2&width=200&height=200)

Respectively, SDSS J235925.15-102608.8 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587727225690063043) (DR7 ObjId 587727225690063043, z=0.305), and SDSS J155752.37+273049.5 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587736618787602957) (DR7 ObjId 587736618787602957, z=0.389). These two images have the same scale as the first of the M81 images.

What if all the galaxies were shown with the same physical scale? That is, if, in each image, 1 pixel corresponded to, say, 3,000 light-years? Here they are, in the same order they appear in this post [2]

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.8875&dec=69.065&scale=52.9&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=214.59292&dec=52.71833&scale=0.24&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=189.99764&dec=-11.62214&scale=13.1&width=200&height=200)
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=14.1777521&dec=-9.91386599&scale=2.52&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)

It is traditional to add a scale bar to images, to give the eye a chance to appreciate the size better. I'm going to go with a somewhat different tradition, I'm going to put a circle around the nucleus of each of these six galaxies, one that is 36 kpc in radius - this is just shy of 120 thousand light-years. How big is 120 thousand light-years? Well, the lovely Large Magellanic Cloud, a satellite galaxy of our own, is estimated to be just ~150 thousand light-years away, so, for a galaxy, it's pretty awesomely big ...

(http://i888.photobucket.com/albums/ac85/JeanTate/M8190036.jpg) (http://i888.photobucket.com/albums/ac85/JeanTate/SDSS1418_524390036.jpg) (http://i888.photobucket.com/albums/ac85/JeanTate/M10490036.jpg)
(http://i888.photobucket.com/albums/ac85/JeanTate/NGC30990036.jpg) (http://i888.photobucket.com/albums/ac85/JeanTate/SDSS2359-102690036.jpg) (http://i888.photobucket.com/albums/ac85/JeanTate/SDSS1557_273090036.jpg)

So, M81, despite appearances, isn't that big of a deal, so far as spiral galaxies go. And SDSS J141822.30+524306.1 is even wimpier, despite its appearance in the Hubble image. Further, I found two galaxies, at redshifts > 0.3, that are apparently larger than NGC 309 (and are, very likely, even larger than they appear, given that the fainter outer bits - visible in the SDSS image of NGC 309 - would be too faint to show)!  :o  8)

But are these the very biggest spiral galaxies, at z > 0.3, in the entire SDSS footprint? Stay tuned!  ;)

[1] H0 = 71 km/s/Mpc, ΩM = 0.27, and ΩΛ = 0.73; for the cognoscenti, the distances I quote are luminosity distances
[2] the scale is actually ~2930 light-years per pixel, or ~900 pc/pix
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: egalaxy May 16, 2012, 12:16:54 AM
wonderful OOTD and beautiful objects!
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: mitch May 16, 2012, 07:02:55 AM
Wow - boggles the mind :o Nice OOTD  8) 8)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: elizabeth May 16, 2012, 08:53:33 AM
 :D :D  8) 8) 8) Great OOTD!
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: AlexandredOr May 16, 2012, 10:12:06 AM
Ah yes, great OotD !
Thx Jean  :D
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 17, 2012, 12:11:45 PM
For completeness, here, at the same scale as the third M81 image (and the first M104 and NGC 309 images), is the "Or yet larger, NGC 3646 in Leo" from NGC3314's OOTD (this is the largest spiral in the SDSS footprint*):

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=170.42950439&dec=20.1695515&scale=5.0&width=600&height=600)

Taking its redshift as 0.01417, from NED, here's how it would appear at the same 900 pc = 1 pixel scale as the last six images (also with a "36 kpc" circle added); I've also included the corresponding pair for SDSS J155752.37+273049.5:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=170.42950439&dec=20.1695515&scale=3.155&width=200&height=200) (http://i888.photobucket.com/albums/ac85/JeanTate/NGC364690036.jpg)
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200) (http://i888.photobucket.com/albums/ac85/JeanTate/SDSS1557_273090036.jpg)

Oh, and I should also add that the M104 entry (http://www.galaxyzooforum.org/index.php?topic=280086.msg601658#msg601658) in the Messier catalogue LIST is blank, that there's also a corresponding - and more ambitious! - NGC catalogue LIST (http://www.galaxyzooforum.org/index.php?topic=280028.0), but that it lacks even a placeholder for NGC 309 or NGC 3646 :( However, there is a post with NGC 3646 (http://www.galaxyzooforum.org/index.php?topic=273743.msg313019;topicseen#msg313019) in the NGC Catalogue (http://www.galaxyzooforum.org/index.php?topic=273743.0) thread  :), but not one for NGC 309  :(

Is it possible to compare the sizes of spirals, in some quantitative fashion? Such a simple question, yet the answer is surprisingly complicated.  ??? If you want a one word Yes-or-No answer, I'd have to go for "No"  :o; at the short phrase level, "There is a way, but the answers come with caveats, and can be misleading" (OK, maybe not such a short phrase!  ::)).

For example: the SDSS photometric pipeline automatically, and without-fear-or-favor, calculates a robust estimate of the size of galaxies, which it calls "petroRad_r". This is the "Petrosian radius" in the r-band. Since we're looking at spirals, and since spiral galaxies have an "exponential profile" (well, mostly, sorta, with important exceptions, etc, etc, etc), another parameter in the photometric pipeline may be used, "expRad_r". This is the "effective radius" of a "fitted exponential profile", in the r-band. The first (petroRad_r) is helpful because "The aperture 2rP is large enough to contain nearly all of the flux for typical galaxy profiles, but small enough that the sky noise in FP is small"; the latter because the effective radius (re) of an "exponential profile" galaxy is a quantitative, objective measure of its size (you can say, for example, that its "edge" is at 4re). You can read more about this - and a hundred and one other things you never knew you needed to know - at the SDSS SkyServer Algorithm Description page, here (http://cas.sdss.org/astrodr7/en/help/docs/algorithm.asp).  8)

So, you're thinking, since SDSS is totally objective, and its treatment of all galaxies is uniform and identical (think of it as a totally impartial judge), why not just look up the values of petroRad_r and expRad_r for M81, M104, NGC 309, NGC 3646, SDSS J141822.30+524306.1, SDSS J235925.15-102608.8, and SDSS J155752.37+273049.5, convert the angular sizes (in arcsecs) to linear ones (in kpc) using the Ned Wright Cosmology Calculator (NWCC), and award gold/silver/bronze rank the seven galaxies accordingly?

To see why not, let's start with M81 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587738067276857349): clicking on PhotoObj, and scanning down the list, we find that petroRad_r is 52.459774", and that expRad_r is 20.663347"; all impressively precise**. We have to be careful with the NWCC, because M81 is so close that its redshift may not be an accurate measure of its distance; fortunately, we have redshift independent estimates of its distance, so we can work backwards (i.e. plug in different values of z until we get 3.6 Mpc as the distance). Doing that we get 0.017 arcsec per kpc kpc per arcsec as the scale, that almost all of M81's light ("nearly all of the flux") comes from a circle only 892 pc in radius (from the first measure), and that its edge is 1,405 pc from its nucleus (from the second).  :o

Clearly, that's complete nonsense!  >:( You only have to have a look at an SDSS image, with a scale bar, to see how ridiculous this is:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.8875&dec=69.065&scale=1.58448&opt=LG&width=512&height=512)

Obviously, a great deal of M81's light comes from beyond 2' from its nucleus, and 120 > 83 > 52.

The automated photometry pipeline doesn't work for such huge (on the sky) objects as M81!

Maybe it'll work for NGC 309, which has the highest redshift of the galaxies in NGC3314's OOTD? Let's see (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587727226233094186).

petroRad_r is 46.109917", and expRad_r is 21.010206"; at z=0.0178, 1 arcsec is 0.357 kpc, so "almost all" of NGC 309's light comes from within 16.46 kpc of its nucleus, and its edge is at 30 kpc (in the r-band). OK, that works, sorta, but we really should use just two significant digits!

How big, then, are the three distant galaxies, the ones whose names are just "SDSS" followed by strings of numbers? Here's how - radius of the edge (4re,r) - big:

17 kpc (http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=214.59292&dec=52.71833&scale=0.24&width=200&height=200) re,r = 1.15" (4.3 kpc); petroRad_r = 2.53" (9.5 kpc)
53 kpc (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200) re,r = 2.96" (13 kpc); petroRad_r =  7.90" (35 kpc)
81 kpc (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200) re,r = 3.87" (20 kpc); petroRad_r =  7.22" (38 kpc)

Oh, and to give you an idea of just how "sorta" these comparisons are, consider that the estimated value of re for the second galaxy, in the g-band, is 4.36" (makes sense, kinda; the arms look blue), which would put its edge at a whopping 78 kpc from the nucleus!  :o :o :o

Bottom line: these two z > 0.3 spirals are waaaay bigger than any in NGC3314's OOTD (those in the SDSS footprint anyway).

UPDATE: (server's down; I'll edit this post later, and put the numbers in) Server's back up, so I added the numbers for the more distant, huge spiral. I've also added the values for petroRad_r, and amended re to re,r, to show that it's the r-band estimate of re. Too, I put the physical size that each arcsec number corresponds to, at each galaxy's redshift (using the NWCC, and generally accepted values of the parameters). Oh, and I fixed a really silly mistake (how silly? well, the original is still in the post, so you can judge for yourself ...)

* or at least it was at the time NGC3314 wrote that OOTD, back in October, 2009; I do not know if there are any larger ones in DR8
** OK, I'm being unfair; in the list is also the estimated error, which means only the first two, or perhaps three, digits are meaningful
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 17, 2012, 04:29:56 PM
egalaxy, mitch, elizabeth, AlexandredOr, many thanks for your feedback and kind words.

As you might have guessed, from reading my OOTD of last week (http://www.galaxyzooforum.org/index.php?topic=280120.0) if nothing else, I've been bitten by the 'giant spirals at z > 0.3' bug!   :D I intend to do more work have more fun on this topic, and would like to get your inputs on a number of things, if you would be kind enough to spare me your time and attention. Nothing heavy!  ;D For now, just looking at a few images and giving me your opinions; a kind of informal, very-small-scale Galaxy Zoo. For example, do you agree that these two galaxies look very much like (nearly) face-on spirals* (and not at all like edge-on spirals, ellipticals, or mergers)?

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200)

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)

Everyone else reading this: of course I'd be delighted if you were to post an opinion too!  :-*

* even if you can't say, with any certainty, whether they're CW or ACW (well, the first is pretty obvious)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 17, 2012, 05:59:43 PM
(http://i888.photobucket.com/albums/ac85/JeanTate/UGC2885-SARA90036.jpg) (http://i888.photobucket.com/albums/ac85/JeanTate/SDSS1557_273090036.jpg)

That's UGC 2885, with a 36 kpc circle added*. The source is the SARA image which NGC3314 posted, in his 2009 OOTD Spirals big and small (http://www.galaxyzooforum.org/index.php?topic=276492.0). Beside it is the SDSS image of SDSS J155752.37+273049.5, to the same physical scale (i.e. 1 pixel = 900 pc), as I've posted several times before in this thread.

As UGC 2885 is not in the SDSS footprint, I can't say what its estimated petroRad_r and re,r are.  :(

Also, like M81, M104, NGC 3646, and SDSS J141822.30+524306.1, UGC 2885 is not (nearly) face-on to us (unlike NGC 309, SDSS J235925.15-102608.8, and SDSS J155752.37+273049.5), so it's hard to say - just by looking at the image - whether UGC 2885 is bigger than SDSS J155752.37+273049.5 or not.  :'(

* I hope think; there are more sums involved in getting to this image, so more opportunities for me to have made a (silly) mistake or two. If anyone would like to check my sums, please send me a PM, and I'll gladly go over them with you ...  :-*
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: egalaxy May 17, 2012, 10:17:09 PM
i just checked, and someone today edited the NGC 309 place holder in the NGC LIST thread.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Budgieye May 18, 2012, 01:38:28 PM
egalaxy, mitch, elizabeth, AlexandredOr, many thanks for your feedback and kind words.

As you might have guessed, from reading my OOTD of last week (http://www.galaxyzooforum.org/index.php?topic=280120.0) if nothing else, I've been bitten by the 'giant spirals at z > 0.3' bug!   :D I intend to do more work have more fun on this topic, and would like to get your inputs on a number of things, if you would be kind enough to spare me your time and attention. Nothing heavy!  ;D For now, just looking at a few images and giving me your opinions; a kind of informal, very-small-scale Galaxy Zoo. For example, do you agree that these two galaxies look very much like (nearly) face-on spirals* (and not at all like edge-on spirals, ellipticals, or mergers)?

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200)

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)

Everyone else reading this: of course I'd be delighted if you were to post an opinion too!  :-*

* even if you can't say, with any certainty, whether they're CW or ACW (well, the first is pretty obvious)

 

I think there is no doubt that they are both face-on spirals and both Anti Clock Wise

(Follow the arms from the outside-in
That's the way that galaxyies spin)

and here is another biggy,
I think is it very far away with a PhotoZ of about 0.4
so far away that its blue spiral arms are turning green

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=147.98732241&dec=11.73666711&scale=0.2&width=200&height=200&opt=G)
http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587735348022477078
posted by elisabethB
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Blackprojects May 18, 2012, 02:21:22 PM
Ermm this is a Face on Anti Clockwise Spiral but i am wondering if it could also be a Lens?

I May be seeing things others will say are not there!

http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.09903&width=512&height=512&opt=SP&query=&PhotoObjs=on&SpecObjs=on


(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.09903&width=512&height=512&opt=SP&query=&PhotoObjs=on&SpecObjs=on)

This Looks like a Dual Arm Anti Clockwise Spiral with a Possible BAR but with a Possible AGN and Face on But rite at the Telescopes Limmit

http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587736618787602957

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.049515&width=512&height=512&opt=&query=)



Wish there was a better Image?

: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: LynnSeguin May 18, 2012, 02:32:06 PM
Dear Jean,

Thank you for the wonderful and instructive OOTD.  My impression is that these are both ACW; the first, a face on spiral and the second face on with a slight tilt.

Cheers,
Lynn
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Lovethetropics May 18, 2012, 10:44:46 PM
(http://i888.photobucket.com/albums/ac85/JeanTate/UGC2885-SARA90036.jpg) (http://i888.photobucket.com/albums/ac85/JeanTate/SDSS1557_273090036.jpg)

That's UGC 2885, with a 36 kpc circle added*. The source is the SARA image which NGC3314 posted, in his 2009 OOTD Spirals big and small (http://www.galaxyzooforum.org/index.php?topic=276492.0). Beside it is the SDSS image of SDSS J155752.37+273049.5, to the same physical scale (i.e. 1 pixel = 900 pc), as I've posted several times before in this thread.

As UGC 2885 is not in the SDSS footprint, I can't say what its estimated petroRad_r and re,r are.  :(

Also, like M81, M104, NGC 3646, and SDSS J141822.30+524306.1, UGC 2885 is not (nearly) face-on to us (unlike NGC 309, SDSS J235925.15-102608.8, and SDSS J155752.37+273049.5), so it's hard to say - just by looking at the image - whether UGC 2885 is bigger than SDSS J155752.37+273049.5 or not.  :'(

* I hope think; there are more sums involved in getting to this image, so more opportunities for me to have made a (silly) mistake or two. If anyone would like to check my sums, please send me a PM, and I'll gladly go over them with you ...  :-*

Wow!!  The second one is also an ACW spiral!  And it's so beautiful  ;D
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 19, 2012, 06:46:48 AM
Thanks Budgieye, Blackprojects, LynnSeguin, and Lovethetropics!  And thanks all of you who sent me your opinions by PM!! ;D  :-*

Everyone thinks both distant galaxies are spirals.  8)

That has encouraged me to ask you to take a look at these four galaxies, and tell me what you think they are. The choices again (somewhat modified) are:

-> certainly some sort of spiral (if you'd like to say what sort - nearly face-on, barred, ring(ed), CW, ... - that'd be a bonus)
-> certainly an elliptical
-> certainly a merger or overlap
-> not really sure, but more likely to be spiral/elliptical/merger (pick one) than either of the other two choices
-> really, truly, cross-my-heart-and-hope-to-die can't tell! :'( (but for sure it's not a star or an artifact  :D )

If you think a galaxy looks like an edge-on spiral, then it's a spiral (either "certainly" or "more likely than not"); in this case, I'd appreciate it if you could explain why you feel "spiral" and not "cigar-shaped elliptical".

All the galaxies have the same physical scale, 1 pixel = 900 pc [1], and all images are the same size, 200 x 200 pixels.

14: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=141.36910207&dec=39.23165432&scale=0.1969&width=200&height=200) 05: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=217.38945795&dec=30.50017047&scale=0.1976&width=200&height=200)
14: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=141.36910207&dec=39.23165432&scale=0.1969&opt=I&width=200&height=200) 05: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=217.38945795&dec=30.50017047&scale=0.1976&opt=I&width=200&height=200)

41: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=176.01918218&dec=30.31833247&scale=0.1953&width=200&height=200) 11: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.2008&width=200&height=200)
41: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=176.01918218&dec=30.31833247&scale=0.1953&opt=I&width=200&height=200) 11: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.2008&opt=I&width=200&height=200)

Please post your opinions in this thread (though you can PM them to me if you'd prefer).

The labels/numbers are my way of keeping track (sure beats writing out long strings, like SDSS names or ObjIds). For reference, the DR7 ObjIds are, respectively (left to right, top to bottom): 588297865255387308, 587739380987265247, 587741490911772750, 588011219134054611.

[1] assuming generally accepted values for the standard cosmological model; the spectroscopic redshifts of the galaxies are all quite good

UPDATE: Following Lovethetropics' EXCELLENT suggestion (see Reply#15, on the next page), I've added inverted images ...

Thank you VERY MUCH!!!  ;D :-* :-*
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: elizabeth May 19, 2012, 10:10:46 AM
i just checked, and someone today edited the NGC 309 place holder in the NGC LIST thread.
;D Awesome was that because it might be NGC 0309 ?











: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Lovethetropics May 19, 2012, 10:28:20 AM
Jean can we invert the galaxies?  I find it's a very good tool to use while classifying spirals  ;D
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 19, 2012, 10:41:36 AM
Jean can we invert the galaxies?  I find it's a very good tool to use while classifying spirals  ;D

What a fantastic idea!  :o  8) (where's the 'kick-myself-for-not-thinking-of-that smilie?!?  :'()

I'll see what I can do ... (brb)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 19, 2012, 10:51:17 AM
Testing, with yesterday's pair:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2012&opt=I&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&opt=I&width=200&height=200)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Blackprojects May 19, 2012, 10:59:23 AM
Thanks Budgieye, Blackprojects, LynnSeguin, and Lovethetropics!  And thanks all of you who sent me your opinions by PM!! ;D  :-*

Everyone thinks both distant galaxies are spirals.  8)

That has encouraged me to ask you to take a look at these four galaxies, and tell me what you think they are. The choices again (somewhat modified) are:

-> certainly some sort of spiral (if you'd like to say what sort - nearly face-on, barred, ring(ed), CW, ... - that'd be a bonus)
-> certainly an elliptical
-> certainly a merger or overlap
-> not really sure, but more likely to be spiral/elliptical/merger (pick one) than either of the other two choices
-> really, truly, cross-my-heart-and-hope-to-die can't tell! :'( (but for sure it's not a star or an artifact  :D )

If you think a galaxy looks like an edge-on spiral, then it's a spiral (either "certainly" or "more likely than not"); in this case, I'd appreciate it if you could explain why you feel "spiral" and not "cigar-shaped elliptical".

All the galaxies have the same physical scale, 1 pixel = 900 pc [1], and all images are the same size, 200 x 200 pixels.

14: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=141.36910207&dec=39.23165432&scale=0.1969&width=200&height=200) 05: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=217.38945795&dec=30.50017047&scale=0.1976&width=200&height=200)

41: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=176.01918218&dec=30.31833247&scale=0.1953&width=200&height=200) 11: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.2008&width=200&height=200)

Please post your opinions in this thread (though you can PM them to me if you'd prefer).

The labels/numbers are my way of keeping track (sure beats writing out long strings, like SDSS names or ObjIds). For reference, the DR7 ObjIds are, respectively (left to right, top to bottom): 588297865255387308, 587739380987265247, 587741490911772750, 588011219134054611.

[1] assuming generally accepted values for the standard cosmological model; the spectroscopic redshifts of the galaxies are all quite good

OK I had to go into ZOO1 For these Good Job i remember how to do it!

The Search Box

http://cas.sdss.org/astro/en/tools/explore/setId.asp?id=0x082808c340680097

The Galaxys

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=588297865255387308

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587729386064052375

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=587741490911772750

http://cas.sdss.org/astro/en/tools/explore/obj.asp?id=588011219134054611
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: LynnSeguin May 19, 2012, 12:03:01 PM
Good morning Jean.

14:  likely to be a spiral
05:  certainly a spiral
41:  likely to be an elliptical
11:  likely to be a spiral.

Cheers,
Lynn
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Lovethetropics May 19, 2012, 12:44:17 PM
Testing, with yesterday's pair:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2012&opt=I&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&opt=I&width=200&height=200)

Yeah, both are spirals  :-* :-* :-*  YOU ROCK!
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Lovethetropics May 19, 2012, 12:47:11 PM
The first of the four:  Evidently a spiral  ;D

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=141.36911471&dec=39.23166292&scale=0.19806&width=150&height=150&opt=I&query=&InvertImage=on)

The second one:  A somewhat disheveled  spiral

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=131.44601482&dec=44.6758831&scale=0.19806&width=150&height=150&opt=I&query=&InvertImage=on)

Third one, a very distant spiral because it can't be anything else.

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=176.01918484&dec=30.31833545&scale=0.09903&width=150&height=150&opt=I&query=&InvertImage=on)

Last one, al almost edge on spiral because it can't be anything else.

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=199.54819255&dec=62.28281015&scale=0.19806&width=150&height=150&opt=I&query=&InvertImage=on)

Of course I could be wrong, guys?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Blackprojects May 19, 2012, 01:06:41 PM
Number1

Looks Like a Clockwise Spiral with Two Arms but is very Fuzzy!

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=141.36911471&dec=39.23166292&scale=0.049515&width=512&height=512&opt=&query=)

Number 2

Also looks like a Fuzzy Clockwise Spiral with a possible Polar Ring!

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=131.44601482&dec=44.6758831&scale=0.049515&width=512&height=512&opt=&query=)

Number 3 is a Faint Fuzzy!

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=176.01918484&dec=30.31833545&scale=0.049515&width=512&height=512&opt=&query=)

Number 4 is a Clockwise Spiral!

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=199.54819255&dec=62.28281015&scale=0.09903&width=512&height=512&opt=&query=)



: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Geoff May 19, 2012, 02:45:15 PM
My take on these: 14, 5 and 11 are spirals. 41 is probably elliptical.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 19, 2012, 02:56:55 PM
Thank you Lynn, Aida, BP, and Geoff!  ;D

An especial thanks to Blackprojects: Lovethetropics pointed out that many of us zooites like to look at inverted images - in addition to, or instead of - straight ones, to do galaxy classification; you've pointed out that some of us zooites like to use bigger images, where the object fills at least half the image (in some sense). I'll try to include such images in future ...
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Blackprojects May 19, 2012, 07:29:37 PM
Jean

Zooites From Zoo1 Day"s Had An intresting and Steep Education with Much PRODDING by Fellow ZOOITES into Doing things the Correct way.

The Problem was there was No Manual on how to do Things and Once we found out we could go of Exploring in the System well that opend up an Entire Can of Worms!.

Leading to all kinds of intresting Didcoveries !

Aida"s (Lovethetropics) Quasar hunt was one of those She found 1,000s and i sorted them out and posted them teaching me how to Spot them by Spectrum!
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: jules May 19, 2012, 10:27:58 PM
My take on these: 14, 5 and 11 are spirals. 41 is probably elliptical.

I agree with Geoff! :)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 08:41:10 AM
Jean

Zooites From Zoo1 Day"s Had An intresting and Steep Education with Much PRODDING by Fellow ZOOITES into Doing things the Correct way.

The Problem was there was No Manual on how to do Things and Once we found out we could go of Exploring in the System well that opend up an Entire Can of Worms!.

Leading to all kinds of intresting Didcoveries !

Aida"s (Lovethetropics) Quasar hunt was one of those She found 1,000s and i sorted them out and posted them teaching me how to Spot them by Spectrum!

What you're highlighting is, I think, an aspect which none of the zookeepers seems to have investigated, explicitly (at least, as far as I know ... which isn't much); namely that the specifics of how an individual zooite does their best (more accurate, most convenient, fastest, whatever) classifying vary from zooite to zooite. An interesting corollary might be that there are ways of presenting images that might be even better, in terms of speed/accuracy/etc of classifying, ones that no one has investigated yet. And since images are simply data, or a particular visualization of data, it shouldn't matter at all how the data are manipulated (as long as no visual artifacts are created, of course!).

Have you ever seen any of the colorized images joinpep has made?

jules: many thanks!  ;D :-*
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: jules May 20, 2012, 10:31:28 AM
What you're highlighting is, I think, an aspect which none of the zookeepers seems to have investigated, explicitly (at least, as far as I know ... which isn't much); namely that the specifics of how an individual zooite does their best (more accurate, most convenient, fastest, whatever) classifying vary from zooite to zooite. An interesting corollary might be that there are ways of presenting images that might be even better, in terms of speed/accuracy/etc of classifying, ones that no one has investigated yet. And since images are simply data, or a particular visualization of data, it shouldn't matter at all how the data are manipulated (as long as no visual artifacts are created, of course!).
Interesting thought. One thing I did pick up on during the Zooniverse conference was that the presentation of each projects' set of images (size, resolution, wavelength, overlap of image edges etc) is very carefully considered beforehand and is always set up very much with future data reduction in mind. Another consideration is consistency - ie we are all presented with exactly the same image and all allowed to explore the various tools at exactly the same stage in classifying. (Otherwise our clicks would be meaningless to analyse!)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 11:20:57 AM
What you're highlighting is, I think, an aspect which none of the zookeepers seems to have investigated, explicitly (at least, as far as I know ... which isn't much); namely that the specifics of how an individual zooite does their best (more accurate, most convenient, fastest, whatever) classifying vary from zooite to zooite. An interesting corollary might be that there are ways of presenting images that might be even better, in terms of speed/accuracy/etc of classifying, ones that no one has investigated yet. And since images are simply data, or a particular visualization of data, it shouldn't matter at all how the data are manipulated (as long as no visual artifacts are created, of course!).
Interesting thought. One thing I did pick up on during the Zooniverse conference was that the presentation of each projects' set of images (size, resolution, wavelength, overlap of image edges etc) is very carefully considered beforehand and is always set up very much with future data reduction in mind. Another consideration is consistency - ie we are all presented with exactly the same image and all allowed to explore the various tools at exactly the same stage in classifying. (Otherwise our clicks would be meaningless to analyse!)

I'm sure this is so (at least I'd certainly hope it were so!)

But even here, in GZ classifications, we can choose to invert the images we're presented. And no one has control over each zooite's browser settings (well, other than the zooites themselves!  ;) ). In fact, if I recall correctly, in Ice Hunters (or was it Moon Zoo?) the instructions (or guide, in the forum) explicitly includes advice on how to modify the parameters of the browser image display.

Anyway, for what I'm trying to do here*, I'd like the long-term zooites who are having a go at classifying - visually! re morphology! - these "80 pixel fuzzballs" to give it their best shot. In other words, this is my 'committee of experts', partly because many of you are better at this than I am.

* well, today; this mini-project has undergone many twists and turns  :P
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: jules May 20, 2012, 01:30:35 PM
Yes - you're right! There are user-controlled browser and settings related differences which can't be avoided. Ah well - as consistent as possible then!! ;)

Interesting experiment you have developed here! Looking forward to the results. :D 8)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 02:27:10 PM
Thanks jules. Yes, whatever they are, the results will be interesting!  ;D

I'm delighted that fellow zooites are also interested in this project!  8)

I've sent a third lot of candidates out, by PM. If you didn't get a PM from me, and would like a chance to classify them, please send me a PM.

: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 05:26:40 PM
For comparison, here is a giant elliptical (same 1 pixel = 900 pc scale, 36 kpc circle added):

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=30.86961769&dec=-9.81667008&scale=0.1939&width=200&height=200) (http://i888.photobucket.com/albums/ac85/JeanTate/58772717846278984990036.jpg)

SDSS J020328.70-094900.0 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587727178462789849) (DR7 ObjId 587727178462789849), z=0.322

I've begun my third CasJobs; here are a couple of early finds:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=353.61864989&dec=0.46689395&scale=0.2&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=130.65180886&dec=29.42753694&scale=0.2&width=200&height=200)

SDSS J233428.47+002800.8 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=588015509803434248) (DR7 ObjId 588015509803434248), z=0.426 (left; posted before by gumbosea (http://www.galaxyzooforum.org/index.php?topic=6927.msg295666#msg295666), in the possible strong gravitational lenses thread)
SDSS J084236.43+292539.1 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587735042539127126) (DR7 ObjId 587735042539127126), z=0.416 (right; posted at least four times before, first - as far as I can tell - by gz (http://www.galaxyzooforum.org/index.php?topic=90.msg34657#msg34657), in the Ring Galaxy thread)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: paulrogers May 20, 2012, 05:41:18 PM
Anyway, for what I'm trying to do here*, I'd like the long-term zooites who are having a go at classifying - visually! re morphology! - these "80 pixel fuzzballs" to give it their best shot. In other words, this is my 'committee of experts', partly because many of you are better at this than I am.

In classifying I have always insisted on clear evidence of a spiral structure, not just impressions or hints.  If it's a "fuzzball", that doesn't cut it.  I've seen times when there's just a hint of slightly streaky darkening in an image, but I've rejected it as evidence of an arm like structure, knowing that there could be intervening gas clouds.  For me it'd have to be a pretty sharp 80 pixels!  Fuzzballs need not apply.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 06:01:10 PM
Anyway, for what I'm trying to do here*, I'd like the long-term zooites who are having a go at classifying - visually! re morphology! - these "80 pixel fuzzballs" to give it their best shot. In other words, this is my 'committee of experts', partly because many of you are better at this than I am.

In classifying I have always insisted on clear evidence of a spiral structure, not just impressions or hints.  If it's a "fuzzball", that doesn't cut it.  I've seen times when there's just a hint of slightly streaky darkening in an image, but I've rejected it as evidence of an arm like structure, knowing that there could be intervening gas clouds.  For me it'd have to be a pretty sharp 80 pixels!  Fuzzballs need not apply.

Thanks!

Of the six images I've posted so far, in this thread, of z>0.3 spiral galaxy candidates, which would you classify as spirals (if you don't mind me asking)?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 06:32:41 PM
Oh, and I forgot to add: in this particular mini-project, 'spiral galaxy' has a somewhat non-standard definition.

Yes, galaxies with clearly identifiable arms are spirals. So are, for my mini-project, "flocculent spirals" - "The primary characteristic of flocculent spiral galaxies is the disjoint nature of the individual arms. The prototype is NGC 2841, ..." (source (http://ned.ipac.caltech.edu/level5/Elmegreen/Elm3.html); check out this set of Hubble images of NGC 2841 (http://www.spacetelescope.org/news/heic1104/)) - barred spirals (even if the arms aren't easy to see), edge-on (or nearly edge-on) spirals, ring and ringed galaxies (but not polar ring galaxies), ... in fact, almost every kind of galaxy except ellipticals!  :o Just about the only other exceptions are obvious mergers, and overlaps (where the morphology of the z>0.3 galaxy - whether foreground or background - can't be ascertained, because of the overlap).

Unfortunately, the scope and objectives of this mini-project are rather, um, fluid  :(
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: paulrogers May 20, 2012, 08:39:32 PM
Of the six images I've posted so far, in this thread, of z>0.3 spiral galaxy candidates, which would you classify as spirals (if you don't mind me asking)?

Only the last, provisionally.  I don't absolutely have to see arms, because these elongated ovals are not stable unless they have angular momentum, i.e. are tilted spirals.  At some distant point, we just can't see well enough to see the arms.  Are there non-spiral ellipticals that are severely flattened like that?  Well, perhaps, but I'd rather bet on tipped spirals.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 20, 2012, 10:06:52 PM
Anyway, for what I'm trying to do here*, I'd like the long-term zooites who are having a go at classifying - visually! re morphology! - these "80 pixel fuzzballs" to give it their best shot. In other words, this is my 'committee of experts', partly because many of you are better at this than I am.

In classifying I have always insisted on clear evidence of a spiral structure, not just impressions or hints.  If it's a "fuzzball", that doesn't cut it.  I've seen times when there's just a hint of slightly streaky darkening in an image, but I've rejected it as evidence of an arm like structure, knowing that there could be intervening gas clouds.  For me it'd have to be a pretty sharp 80 pixels!  Fuzzballs need not apply.
Oh dear, a serious mis-communication that I was totally blind to  :( :'(

The fuzzballs are ~80 pixels wide, or ~40 pixels in radius; that means the total number of 'spatial signal pixels' is ~5,000. And as they're RGB pixels, that means ~15,000  8)

I once heard that Fritz Zwicky* could glance at a photographic plate - which is, of course, monochrome - see a tiny blob, and declare it to be a spiral (or elliptical, or ...). If you were to examine the plate with a microscope, you might find that the blob was comprised of ~ten grains of silver**. An 80 pixel wide fuzzball is a veritable cornucopia of data compared with ten grains of silver ...

* or was it Allan Sandage?
** astronomers used glass plates covered with a photographic emulsion, the key ingredient in it being a silver halide (or a combo of silver halides). When hit by a photon (or hundred) the Ag-Cl (say) bond in a crystal would break, releasing the chlorine. In developing the plate, grains in which some AgCl molecules had been zapped by photons would be converted entirely to silver metal; these would be the specks on the plate.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 21, 2012, 09:39:24 AM
Here's another "run 3" find (I've already posted it in the possible strong gravitational lens thread):

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=149.82090922&dec=1.03307371&scale=0.2&width=300&height=300)

SDSS J095917.01+010159.0 (http://cas.sdss.org/dr6/en/tools/explore/obj.asp?id=587727942423216392) (DR7 ObjId 587727942423216392), z=0.446.


But even here, in GZ classifications, we can choose to invert the images we're presented. And no one has control over each zooite's browser settings (well, other than the zooites themselves!  ;) ). In fact, if I recall correctly, in Ice Hunters (or was it Moon Zoo?) the instructions (or guide, in the forum) explicitly includes advice on how to modify the parameters of the browser image display.

Anyway, for what I'm trying to do here*, I'd like the long-term zooites who are having a go at classifying - visually! re morphology! - these "80 pixel wide fuzzballs" to give it their best shot. In other words, this is my 'committee of experts', partly because many of you are better at this than I am.

* well, today; this mini-project has undergone many twists and turns  :P
(The bolding is not in the original, and I added the bit about the diameter of the fuzzball  ;))

I'm reading "Thinking, Fast and Slow", by Daniel Kahneman, and remembered reading this passage:
: Kahneman
We have all heard such stories of expert intuition: the chess master who walks past a street game and announces "White mates in three" without stopping, or the physician who makes a complex diagnosis after a single glance at a patient. Expert intuition strikes us as magical, but it is not. [...] The psychology of accurate intuition involves no magic. Perhaps the best short statement of it is by ... who studied chess masters and showed that after thousands of hours of practice they come to see the pieces on the board differently from the rest of us. [...] "The situation has provided a cue; this cue has given the expert access to information stored in memory, and the information provides the answer. Intuition is nothing more and nothing less than recognition."

Here too are a few snippets from jules' excellent blog entry (http://astrojules.wordpress.com/2012/05/17/zoocon1/) on the first Zooniverse Project Workshop (context is important; I urge you to read the whole thing):
: jules
Some of the Galaxy Zoo images were too indistinct for computers to sort reliably. ... Classifications need to be good. Quality as well as quantity is needed. Users were weighted by matching with expert classification (Kevin.)

The advantages are: ... Leaves room for other interpretations – ie doesn’t confine people to classifying in a certain way. A rigid tutorial could result in predefined answers.

Issues to consider: User modelling / user performance – some people are better than others at classifying

Basic idea: ... weight users, include some expert measurements, make the casual count – ie a single classification is important (Most people on Galaxy Zoo do a couple of clicks and then leave.) Half the data are from users spending less than 1 minute classifying

From the classifications I've received so far, of the (now) ten galaxies (distant, giant spiral candidates), I would say there are some with Zwicky/Sandage-like expertise!  :o  ;D  8)  8)

Thank you very much, fellow zooites!  :-*
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Blackprojects May 22, 2012, 12:55:02 AM
ZOOITESThose with Several 1,000 Classifactions or More are Probably the People who can answer all the questions as we Devellop a Sense of what a GALAXY is Just by a Quick look!

Some of us have gone onto Other Zoo"s and Hardly spend any time on Hubble Zoo any more my self i am a Dedicated Super Novae ZOOITE  With 15,325 Sorted so Far on SN ZOO Compared with 945 on Hubble Zoo and 4,636 on MoonZoo! ZOO2 and ZOO1 Had a vast amount of Clicks on them!

Yet i am Still only a Begginer Compared with Some of my fellow ZOOITES! Clicks wise!
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: graham d May 22, 2012, 07:50:10 PM
ie a single classification is important (Most people on Galaxy Zoo do a couple of clicks and then leave.) Half the data are from users spending less than 1 minute classifying
This says it all. However, if a few clicks or less than a minute classifying means something important please explain.
Perhaps the best short statement of it is by ... who studied chess masters and showed that after thousands of hours of practice they come to see the pieces on the board differently from the rest of us. [...] "The situation has provided a cue; this cue has given the expert access to information stored in memory, and the information provides the answer. Intuition is nothing more and nothing less than recognition."
A chess master doesn't become a master by chance. As well as innate ability there's constant practice and theoretical study. Infact, for a while the more books one studies the worse ones game gets. This would be philosopher must have been drunk when he wrote that final line.

As for looking at emulsions and chasing the determination of Hubble's constant Sandage appears to have creating two warring factions. Maybe Bill or someone could say some kind words about them both. Zwicky despite his brilliance was pretty un American in his attitude to spherical cows.

Those z>0.3 fuzzballs; you can't beat higher resolution images can you? Hubble zoo images are superb for a while, but we need even more resolution.

 Why choose that lifeless rock; I think I managed a few clicks on it. Compared with the whole heavens surround , why choose that light polluting mass?

As for weather data, some filled in by booze crazed pirates, and ancient Greek classifications. Let them set up their own sites. It's quicker to learn classical Greek and decipher the whole in seconds. What we would all like to know is why Cosmoquest got the boot?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Blackprojects May 22, 2012, 10:19:43 PM
Graham that may be Some thing for a chat in a Pub to Theorise over but not really for here! :o :o :o :o
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate May 31, 2012, 09:49:10 AM
: JeanTate
Time for a history-of-astronomy trivia quiz question: you have all heard, I'm sure, of the fact that some people - even some astronomers - do not accept that the Hubble distance-redshift relationship holds for all galaxies (once you take account of some small, local variations); what role did M81 and NGC 309 play, as evidence against this relationship? For an extra bonus point, what is the name of the astronomer made the connection? For two bonus points, what's wrong with this evidence (that involving M81 and NGC 309)? I'll post answers later.  :D  :-*

Yes, I did say that, back in the very first post, on page one. No answers from me yet, despite my promise.  :( Well, here's a start ...

(http://i888.photobucket.com/albums/ac85/JeanTate/ArpNGC309M81.jpg)

This is Figure 18, from a book by Halton Arp; the caption reads "At its supposed redshift distance, the ScI galaxy NGC 309 is compared to M81, one of the largest galaxies of whose dimensions we can be sure. NGC 309 would be so enormous that it would make M81 look like a knot in one of its spiral arms." (source (http://www.scribd.com/doc/41407655/Halton-Arp-Catalogue-of-Discordant-Redshift-Associations))

I don't know when this was written, but here's my version of this same figure, using distances from NED (and images from SDSS  ;D)

(http://i888.photobucket.com/albums/ac85/JeanTate/NGC309M81SDSS.jpg)

While the two galaxies are still quite different in (estimated) actual size, the disparity has shrunk some; no doubt this is due in large part to better, and more accurate, estimates of the distances to these two galaxies. Estimates which do not rely upon their redshifts, "Redshift-independent distances", as NED puts it.

Zooites have posted many hundred (thousand, actually) examples of Galaxy pairs which overlap but are not merging (http://www.galaxyzooforum.org/index.php?topic=6732.0). Many of these are of galaxies with similar redshifts, but which do not appear to be interacting. One such pair is IC 1252 and companion (I don't know what this companion is called, other than SDSS J171547.77+572209.2)*; they have redshifts of 0.0300 and 0.0319. Look how different in size they appear!  :o 8)

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=258.96002823&dec=57.36677984&scale=0.15&width=512&height=512)

One more thing: other than that it uses the logical fallacy "argument from incredulity" (or appears to use that fallacy), what's wrong with the evidence presented in Figure 18?

* strangely, I could find no post, by any zooite, of either, using their DR7 ObjIds, in this forum; perhaps they're posted using different identifiers? Thanks to NGC3314 for bringing this pair to my attention.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: NGC3314 May 31, 2012, 06:18:25 PM

* strangely, I could find no post, by any zooite, of either, using their DR7 ObjIds, in this forum; perhaps they're posted using different identifiers? Thanks to NGC3314 for bringing this pair to my attention.

Not that it's much less mysterious, but my detailed document (one of the PDFs  at data.galaxyzoo.org/overlaps.html) says that I picked it up from the forum but outside the overlap thread on 28 April 2009.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 03, 2012, 07:45:06 PM
A VERY BIG THANK YOU for all my fellow zooites who provided me with your classifications of the candidates!  :-*  8)  ;D

In Galaxy Zoo 1 : Data Release of Morphological Classifications for nearly 900,000 galaxies (http://arxiv.org/abs/1007.3265) - the paper which presents the results of the millions of zooite clicks, in the original Galaxy Zoo - there are three sets of galaxies*: superclean, clean, and greater. What does this mean? A galaxy in the clean set had "at least 80 per cent of the vote [...] assigned a classification"; in other words, if >80% of the zooite classification clicks for a galaxy were "Elliptical galaxy", this galaxy would be in the clean set. The threshold for a galaxy to be in the superclean set is 95%, and for the greater set, 51%.

The original Galaxy Zoo collected ~30+ votes (clicks) for every object; in my 'giant, distant spirals' project I count success as getting 10+ independent classifications. I've now got at least that number for ~half my candidates, and am close to getting 10+ for the other half (if you'd like to have a go at classifying, and haven't received a PM from my, with an invitation, well, you're more than welcome to join in!  :D Just send me a PM  ;)).

Four of my candidates are superclean; in fact, all zooites who classified these voted 'spiral'.  8) Here they are, together with my tracking numbers:

02: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=19.49383773&dec=-8.9779174&scale=0.1876&width=200&height=200) 03: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)
05: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=217.38945795&dec=30.50017047&scale=0.1976&width=200&height=200) 21: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2012&width=200&height=200)

Here are some of the additional comments on each:

02: Anti-clockwise; disrupted; not 'regular'
03: (Nearly) face-on; with a slight tilt; anti-clockwise
05: Somewhat disheveled; disturbed; fuzzy; at least two fairly tight arms
21: Face-on; anti-clockwise; two-armed; with an oval bar

There are five others which belong to the clean set (but not the superclean one); interestingly, they are all classified as spirals.

The galaxy with the greatest proportion of votes for 'elliptical' belongs to the greater set:

17: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=129.54082023&dec=34.62518942&scale=0.2193&width=200&height=200)

(more later).

Oh, for completeness, I should add that these results are preliminary; I need to check everything once more, to make sure I haven't made any mistakes.

* I'm referring to those in Table 2 of that paper
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 07, 2012, 03:06:41 PM
What a difference just four days makes!  :)

I've now received, from you dear fellow zooites, 11 independent classifications of all 53 candidates (and more than 11 for ~half of them, with six having 15 or more). So, once again, a very big thank you!  8) :-* ;D

For those of you who have PMs from me, with galaxies to classify, which you have not yet replied to: take your time; whenever you get around to classifying and sending me a reply PM, it'll be cool (all independent classifications are good, and welcome). If you're interested in being involved in any future classifications (etc), in my giant, distant spirals project, welcome; simply send me a PM letting me know (and thanks to those who have already expressed just such an interest  :-*).

In addition to the four superclean spirals in my last post, there are now five six clean ones*  8). Here they are, together with my tracking numbers:

01: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=208.25715643&dec=13.48091001&scale=0.1969&width=200&height=200) 11: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.2008&width=200&height=200) 12: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=29.27199826&dec=-8.89445153&scale=0.1992&width=200&height=200)
14: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=141.36910207&dec=39.23165432&scale=0.1969&width=200&height=200) 15: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=192.36868595&dec=20.36352642&scale=0.1976&width=200&height=200) 49: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=194.40605414&dec=66.70542029&scale=0.1845&width=200&height=200)

Here are some of the additional comments on each:

01: with distinct bluer arms; face-on. Several comments to the effect that this may be an overlap or merger; e.g. One-armed spiral overlapped by a smaller, blue, bulgeless spiral
11: Spiral edge on; very strong nucleus, possible dust lane; sort of sombrero like. Spiral or S0, hint of blue at edges makes me favor spiral
12: slightly tilted spiral, possibly ACW; ACW barred spiral?
14: Clockwise spiral with two arms but is very fuzzy; could even be a ring; spiral, disturbed
15: Tilted spiral; disturbed spiral; spiral: ionized gas, AGN, possible merger
49: Almost ring-like spiral; System possibly ringed; tight, probable AGN

With the extra votes, the #17 - the galaxy which topped the poll re "elliptical" - lost its crown; #51 is the new king of the ellipticals (it's also in the greater set, not the clean one). In addition, there are two others with the same proportion of "elliptical votes" as #17. Here are these three:

51: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=207.83363255&dec=15.25034823&scale=0.1976&width=200&height=200) 23: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=172.70658612&dec=32.08819266&scale=0.1859&width=200&height=200) 56: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=207.66769461&dec=27.70859011&scale=0.2012&width=200&height=200)

And some comments, also reflecting the diversity of classifications:

17: Could be an elliptical, but I've no way of describing the mess all round it; could be elliptical, but the colouring makes me think it could be a big bulged spiral with thin arms, Don't know
51: Merger, has more or less spume, the center is not perfectly round; elliptical, there seems to be some kind of structure but it's not clear to me whether this is part of the galaxy or background
23: possible lens? possible merger; Surroundings would make sense for a brightest cluster galaxy
56:  possibly overlap; AGN; Don't know, some overlapping weirdness going on...

No galaxy in the other two categories - Merger/Overlap and Don't Know^ - belongs to either the superclean or clean sets, and only one to the greater set. That galaxy is #42, a Merger/Overlap. Here it is, along with a selection of additional comments:

42: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=178.00084075&dec=33.22835712&scale=0.1811&width=200&height=200) Two or three way mergers or overlaps; really don't know, a lot of things come to mind, but spiral isn't one; cool gathering; possible lens

Later: some of the candidates with 'split personalities'; i.e. those for which there were several votes in two or more categories. Also, ~15 of these appear in Table 3; it may be interesting to compare the zooite votes for these, in the original Galaxy Zoo, with those done for this project.

* The one extra, from my last post, is in the candidates for which I had not yet received at least ten independent classifications. These results are preliminary; I need to check everything once more, to make sure I haven't made any mistakes. As I'll be (mostly) offline for the next week or so, that won't be done for at least ten days yet

^ Strictly speaking, there's also the Star/Artifact category, but that got zero votes
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 20, 2012, 10:30:47 PM
Here the objects which are in the greater 'spiral' set (but not the clean one), in approximate order of agreement [1]

49: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=194.40605414&dec=66.70542029&scale=0.1845&width=200&height=200) 52: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=170.32225969&dec=19.67555086&scale=0.1972&width=200&height=200) 19: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=223.2003546&dec=0.32501747&scale=0.2012&width=200&height=200)
22: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=119.83421081&dec=35.31764148&scale=0.1916&width=200&height=200) 48: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=182.94836038&dec=34.14759077&scale=0.2008&width=200&height=200) 55: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=165.33109844&dec=17.65911684&scale=0.2012&width=200&height=200)
07: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=116.47419608&dec=40.99362399&scale=0.1597&width=200&height=200) 33: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=50.12410042&dec=0.5315734&scale=0.1728&width=200&height=200) 09: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=218.27178384&dec=17.37439952&scale=0.1916&width=200&height=200)
13: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=223.6517255&dec=22.7741457&scale=0.1672&width=200&height=200) 18: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=323.6917518&dec=-0.45199739&scale=0.2008&width=200&height=200) 31: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=143.05912712&dec=62.36088271&scale=0.2&width=200&height=200)
25: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=209.49237884&dec=14.909207&scale=0.2012&width=200&height=200) 04: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=133.0014753&dec=36.55643476&scale=0.1895&width=200&height=200)

And a selection of the additional comments:
49: Huh?!?  ??? Didn't I post this already, as a clean spiral? Yes, I did; however, since then some extra votes came in, and it got demoted.  :P
52: slightly edge-on spiral - possibly ACW; looks like a compact elliptical with a diffuse ring; side-on spiral but disturbed
19: who was looking for square galaxies? it is a spiral with some confidence....a weird absorption line too; DK imperfect image difficult to decide; disturbed
22: One of those spirals with an S-shape within the nucleus (what I think of as a spiral within a spiral);  it might be a merger as I believe to see a split nucleus; poss ACW
48: Probably also interacting or with low-surface-brightness superposition; Merger - looks like it has an extra nucleus; No contest, interestingly colored nucleus, AGN 4 sure
55: ACW, possible AGN; merger,  has more or less spume, the center is not perfectly round; One arm system
07: Spiral, because of fuzziness; Possible barred system and cw-rotation; E possibly background structures and certainly no spiral arms identifiable
33: slightly tilted spiral
09: Large bulge lenticular; poss face-on spiral; ACW
13: Not as obvious that it could be a disk as some others; SO type starting some branch offices?
18: spiral, ringed; Sp in merger or with superimposed second galaxy with cores quite close; Sp, AGN, Awww, it's blushing
31: M /superposition; spiral, disturbed, possible AGN; don't know, ionized gas
25: merger/spiral; elliptical: AGN
04: I'm saving this for a later post ...  ;)

[1] i.e. percentage of votes for 'spiral'. Note that these results are preliminary; I need to check everything once more, to make sure I haven't made any mistakes (yes, I'm back online  :), but haven't done the checking yet  :()
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 21, 2012, 07:09:05 PM
So, I've posted the four superclean galaxies (all spirals), five clean ones (also all spirals), and 19 greater ones (14 spirals, four ellipticals, and one overlap/merger) [1].

There are six more greater objects, all ellipticals:

41: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=176.01918218&dec=30.31833247&scale=0.1953&width=200&height=200) 10: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=233.22409237&dec=30.34983327&scale=0.1788&width=200&height=200) 30: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=143.80004848&dec=39.8144139&scale=0.22&width=200&height=200)
50: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=216.24291353&dec=1.15362374&scale=0.2012&width=200&height=200) 54: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=218.79291943&dec=8.71874255&scale=0.1788&width=200&height=200) 28: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=27.58864136&dec=-10.09181444&scale=0.1976&width=200&height=200)

A selection of additional comments:

41: a very distant spiral because it can't be anything else; Not spiral, AGN or something, but really not clear enough to tell; Faint Fuzzy
10: looks like central galaxy of cluster; Elliptical (blue or not), spectrum is (of all things ) a strong LINER, fairly rare in luminous galaxies
30: possible AGN
50: Poss tilted spiral
54: Merger, nice color; elliptical: QSO
28: Fireworks! could this be an elliptical merging with smaller galaxies around it?

Since this project is about finding giant, distant spirals, which of the candidates can we say - with considerable confidence - are not spirals (based on the zooites' votes)? This isn't quite as straight-forward as it might seem; for example, a greater elliptical could become a greater spiral if one zooite vote were to switch, as in 'in principle' could. For the objects in this sample, however, no 'elliptical' classification is so insecure: in each of the ten cases, at least two extra votes would be needed to turn it into a greater spiral. The one greater merger/overlap is also like this; in fact, it received zero 'spiral' votes.

Are there any other galaxies which are clearly not spirals (even if it's not clear what they are)? Yes, two:

35: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=120.21687326&dec=25.52569107&scale=0.151&width=200&height=200) 43: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=159.76945373&dec=14.84742901&scale=0.176&width=200&height=200)

35: Spiral arms are evident, but the object seems rather confused, so perhaps a merger? This object had the highest number of "Don't Know" votes; just one more and it would have been the sole greater Don't Know object!  :P
43: two or three way mergers or overlaps; really don't know, a lot of things come to mind, but spiral isn't one

And there are also four where the voting was split as equally as possible [2], across the three main 'affirmative' categories (i.e. spiral, elliptical, merger/overlap); interestingly, the number of "don't know" votes were zero, one, two, and three!

16: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=211.36635821&dec=26.32197591&scale=0.1953&width=200&height=200) 44: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=186.6227793&dec=48.11966033&scale=0.1788&width=200&height=200) 39: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=194.16396518&dec=6.15223627&scale=0.1633&width=200&height=200)
34: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=240.75416488&dec=37.1463647&scale=0.1895&width=200&height=200)

Finally, consider these two:

04: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=133.0014753&dec=36.55643476&scale=0.1895&width=200&height=200) 57: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=190.51568591&dec=25.58472112&scale=0.2012&width=200&height=200)

Both got the same percentage of votes for Overlap/Merger (45%), but #57 had one vote for Elliptical (and the rest for Spiral), whereas all other votes for #04 were Spiral (putting it into the greater class).

[1] Note that these results are preliminary; I need to check everything once more, to make sure I haven't made any mistakes
[2] Perfect equality is possible only if the total number of non-Don't Know votes is divisible by 3; otherwise, votes for two (of three) categories equal, and for the third just one more (or less)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 21, 2012, 10:13:40 PM
Later: some of the candidates with 'split personalities'; i.e. those for which there were several votes in two or more categories. in two or more categories.

I posted several of these in my last post.

Also, ~15 of these appear in Table 3; it may be interesting to compare the zooite votes for these, in the original Galaxy Zoo, with those done for this project.

Turns out there are 13. Of these, I have already posted the 'giant, distant spiral project team' consensus for seven. How do these expert zooites' votes compare with those from GZ1 [1]? Here's how (GDSPT = giant, distant spiral project team; Sp=spiral; E=elliptical; O/M=overlap/merger; DK=Don't Know):

09: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=218.27178384&dec=17.37439952&scale=0.1916&width=200&height=200) GDSPT: 62% Sp (GZ1 7%), 31% E (79%), 8% O/M (0%), 0% DK (14%).
07: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=116.47419608&dec=40.99362399&scale=0.1597&width=200&height=200) GDSPT: 69% Sp (GZ1 0%), 8% E (84%), 15% O/M (0%), 8% DK (16%).
44: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=186.6227793&dec=48.11966033&scale=0.1788&width=200&height=200) GDSPT: 36% Sp (GZ1 13%), 27% E (42%), 27% O/M (7%), 9% DK (39%).
34: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=240.75416488&dec=37.1463647&scale=0.1895&width=200&height=200) GDSPT: 27% Sp (GZ1 0%), 27% E (73%), 18% O/M (4%), 27% DK (23%).
35: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=120.21687326&dec=25.52569107&scale=0.151&width=200&height=200) GDSPT: 0% Sp (GZ1 10%), 27% E (41%), 27% O/M (0%), 45% DK (48%).
39: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=194.16396518&dec=6.15223627&scale=0.1633&width=200&height=200) GDSPT: 27% Sp (GZ1 8%), 27% E (67%), 27% O/M (6%), 18% DK (19%).
04: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=133.0014753&dec=36.55643476&scale=0.1895&width=200&height=200) GDSPT: 55% Sp (GZ1 24%), 0% E (0%), 45% O/M (45%), 0% DK (31%).

I'll post the other six later. For now, what do you make of the - for the most part - rather substantial differences in the GDSPT and GZ1 votes?

[1] Most have ~30 votes; #07 has 57 votes, and #39 48.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 22, 2012, 07:53:18 PM
That's not a particularly impactful way to display the distribution of classifications, is it?

How about this:

09: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=218.27178384&dec=17.37439952&scale=0.1916&width=200&height=200) This project: SemGZ1: sE.d  Side-by-side: SseEm..d
07: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=116.47419608&dec=40.99362399&scale=0.1597&width=200&height=200) This project: Semd   GZ1: .E.d  Side-by-side: S.eEm.dd
44: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=186.6227793&dec=48.11966033&scale=0.1788&width=200&height=200) This project: Semd  GZ1: sEmd  Side-by-side: SseEmmdd
34: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=240.75416488&dec=37.1463647&scale=0.1895&width=200&height=200) This project: semGZ1: .Emd  Side-by-side: s.eEmmdd
35: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=120.21687326&dec=25.52569107&scale=0.151&width=200&height=200) This project: .emd  GZ1: se.d  Side-by-side: .seem.dd
39: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=194.16396518&dec=6.15223627&scale=0.1633&width=200&height=200) This project: semd  GZ1: sEmd  Side-by-side: sseEmmdd
04: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=133.0014753&dec=36.55643476&scale=0.1895&width=200&height=200) This project: S.m.  GZ1: s.md  Side-by-side: Ss..mm.d

Key:
SSss. - classifications as Spiral, clean, greater, 25 to <50%, >5 to <25%, and <5%, respectively
Ditto for EEee. classifications as Elliptical, MMmm. Overlap/Merger, and DDdd. Don't Know
The classifications in this project, the giant, distant spiral project distinguished from those of the original Galaxy Zoo by use of italics

What do you think?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: LankyYankee June 23, 2012, 08:44:33 PM
I know that NGC 1262 here isn't exactly what you're looking for because it's too close to us at z=0.116, but assuming its redshift is correct, it is a VERY big spiral, so I thought I'd mention it to the the giant spiral hunters.

(http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=48.88992096&dec=-15.87930403&scale=0.1980635&width=512&height=512&opt=&query=)

1237667244335038577 (http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237667244335038577)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 29, 2012, 04:02:54 PM
Thanks LankyYankee!   ;D

Yes, it is huge, isn't it?

petroRad_r is given as 25.396" (this is a rough indication of the size of the galaxy, on the sky), which at z=0.116 is ~53 kpc!  :o

That would make it far bigger than NGC 309 or NGC 3646; I wonder if it appears in David Block's atlas (as mentioned by NGC3314, in his 2009 OOTD (http://www.galaxyzooforum.org/index.php?topic=276492.0))?

It is of comparable size to the giant, distant spirals I've posted in this thread (in fact, likely bigger than all but one or two).   :P

Great find!  8)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 30, 2012, 03:52:32 PM
In light of the newly formed Lens Zoo (Lens Zoo blog is here (http://blog.lenszoo.org/)), I thought it might be appropriate to write a post about #24:

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=168.96625752&dec=1.49862941&scale=0.1825&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=168.96625752&dec=1.49862941&scale=0.1825&opt=I&width=200&height=200)

Three Four (!) zooites who saw this said "lens!"  8) (Well, they weren't as certain as that, but still 25% 33%* isn't bad, as a hit rate, is it?)

Little did any of them know - at the time they viewed the images I PMed - that they were, in fact, looking at a strong gravitational lens!  :o ;D

Back on February 15, 2009 (http://www.galaxyzooforum.org/index.php?topic=6927.msg266714#msg266714), Elisabeth B posted this, without comment, in the Possible strong gravitational lenses thread (it is "Reply #3178", which gives you some idea of how active that thread is!). Just two days' later, astronomer Aprajita responded:
Hi Elizabeth

Well spotted! This is a region that contains a known Massive Cluster (MACS J1115.8+0129) that has been selected in the X-ray (z~0.35). These massive clusters are known to be sites where strong gravitational lensing is likely. Indeed the reddish arc is very likely to be a lensed galaxy. I have attached a HST preview image (png file) of this region with much higher resolution than the SDSS images in which elongated arcs can be clearly seen in this region (but please note the orientation is different to that of the SDSS image - that has north up and east to the left - so don't forget to take that into consideration when you visually compare the two images). The red arc is SDSS 111551.89+012946.7 - marked with a "2" and the lensing galaxy SDSS J111551.90+012955.0 marked with a "1".

Aprajita.

Here's the attached image:
(http://www.galaxyzooforum.org/index.php?action=dlattach;topic=6927.0;attach=14289;image)

Some discussion ensued:

ElisabethB: Woohoo !!  :D This just made my day (even on GZ2 day ! ) is this a new one or is this a known lens ? But just to know we can spot them (see OotD 7th Feb. 2009 (http://www.galaxyzooforum.org/index.php?topic=273781.0)) !

Aprajita: As this is a known cluster which shows arcs and so in that sense it is not "new" but the spectrum (or redshift) of this particular arc has not yet been published. That isn't to say that one of the people who have been studying this cluster does not have other data or confirmation it is indeed a background galaxy that has been lensed but it's just not been published in a journal yet. For usre, giant arcs and strctures like those you see in the HST image can only be from gravitational lensing.

Here's something to think about: the ~50 objects chosen to appear on this Galaxy Zoo version of "Universe's Got Talent" were selected from ~200 found using a very simple Casjobs SQL Search. One of those ~50 turned out to be a confirmed strong gravitational lens. That's 2%, which is an astonishingly high hit rate, given how rare these sorts of lenses are (i.e. not only the existence of an arc etc, but also clearly visible in SDSS images). Could it be that some of the other objects the zooite judges noted as possible lenses are also, in fact, strong gravitational lenses?

No other object, among the 53, got more than a single "possible lens" (or equivalent) comment. One zooite judge made a comment like this about three (other) objects, one about two, and three just one. Here are all eight, in no particular order:

14: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=141.36910207&dec=39.23165432&scale=0.1969&width=200&height=200) 21: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2&width=200&height=200) 17: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=129.54082023&dec=34.62518942&scale=0.2193&width=200&height=200)
19: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=223.2003546&dec=0.32501747&scale=0.2012&width=200&height=200) 10: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=233.22409237&dec=30.34983327&scale=0.1788&width=200&height=200) 23: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=172.70658612&dec=32.08819266&scale=0.1859&width=200&height=200)
56: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=207.66769461&dec=27.70859011&scale=0.2012&width=200&height=200) 42: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=178.00084075&dec=33.22835712&scale=0.1811&width=200&height=200)

What do you think?

* just to be sure, I went back and checked all the additional commentary, from everyone; I found I'd missed one
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 30, 2012, 08:46:04 PM
If zooites had not taken a cold, hard look at the SDSS images of 53 objects selected, how many of 23 they said are spiral* would be identified as such by automated means?

Let's start with colors.

A very easy to apply test of this kind is the one used, in SDSS, to select LRGs, or Luminous Red Galaxies. Here's the intro, in the SDSS DR7 algorithms section (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=170.32225969&dec=19.67555086&scale=0.1972&width=200&height=200), on LRGs (I added a link to the astro-ph abstract, for "Eisenstein et al. (2001)"):
Luminous Red Galaxies (LRG)

SDSS luminous red galaxies (LRGs) are selected on the basis of color and magnitude to yield a sample of luminous intrinsically red galaxies that extends fainter and farther than the SDSS main galaxy sample. Please see Eisenstein et al. (2001) (http://arxiv.org/abs/astro-ph/0108153) for detailed discussions of sample selection, efficiency, use, and caveats.

LRGs are selected using a variant of the photometric redshift technique and are meant to comprise a uniform, approximately volume-limited sample of objects with the reddest colors in the rest frame. The sample is selected via cuts in the (g-r, r-i, r) color-color-magnitude cube.

...

Because the 4000 Angstrom break moves from the g band to the r band at a redshift z ~ 0.4, two separate sets of selection criteria are needed to target LRGs below and above that redshift:

Only two of the 23 spirals have redshifts > 0.4 (#07 and #13), though another two have redshifts close to 0.4, so to be prudent both sets of selection criteria (called "Cuts") should be applied to them (#03 and #33).

All but four (five) of the 23 spirals are too blue to be LRGs, by these criteria. They are:

11: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.2008&width=200&height=200) 15: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=192.36868595&dec=20.36352642&scale=0.1976&width=200&height=200) 13: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=223.6517255&dec=22.7741457&scale=0.1672&width=200&height=200)
07: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=116.47419608&dec=40.99362399&scale=0.1597&width=200&height=200) 09: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=218.27178384&dec=17.37439952&scale=0.1916&width=200&height=200)

#07 fails the Cut II criterion by 0.06 mag, and #09 passes it by 0.04 mag.

Of course, thanks in part to the collective clicking of zooites, we know there are red spirals (and blue ellipticals!), so simply being red doesn't make a galaxy a non-spiral (note to self: in the GZ 'red spirals' paper, what proportion of spirals are red?).

Turning to two other Q&D methods of sorting spirals from ellipticals, the fractional likelihood (of an exponential profile) and the concentration index (see the You Have GOT To Be Kidding Me! (http://www.galaxyzooforum.org/index.php?topic=280195.0) OOTD for details).

To use either of these criteria, it's probably best that there not be any non-galaxy blobs within an arcsec or two of the outer edge. Unfortunately, at z > 0.3, having 'clear space' around the galaxy is not as common as we might like, and so we can really apply these two tests to only ~half the spirals.

Setting the fDeV threshold at 0.6, five spirals fail this test; setting the inverse concentration index threshold at 0.385 (rather conservative), four spirals fail this test.

Three of the 'red' spirals are among those tested; two pass both tests, and one (#11) passes the fDeV test but fails the inverse concentration index one.

Three spirals fail both tests, and two fail the fDeV one, but pass the other. Here are the three 'double failures':

55: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=165.33109844&dec=17.65911684&scale=0.2012&width=200&height=200) 49: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=194.40605414&dec=66.70542029&scale=0.1845&width=200&height=200) 31: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=143.05912712&dec=62.36088271&scale=0.2&width=200&height=200)

And the two 'single failures':

18: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=323.6917518&dec=-0.45199739&scale=0.2008&width=200&height=200) 19: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=223.2003546&dec=0.32501747&scale=0.2012&width=200&height=200)

Would you be surprised to learn that the three 'double failures' are among the bluest galaxies (of the 23)? What might you expect their spectra to show?

The bulge in #19 is huge, and as Karen explained (in the You Have GOT To Be Kidding Me! (http://www.galaxyzooforum.org/index.php?topic=280195.0) OOTD), spirals with huge bulges often have fDeV > 0.6. The center of #18 seems to be double, or perhaps to have a foreground object superimposed; in any case, that's surely enough to produce an fDeV > 0.6.

What if we apply these last two tests to the ten spirals which are compromised by close-in blobs, knowing in advance that they might be unreliable? Well, four pass both tests, two fail the fDeV test but pass the inverse concentration index one, and four fail both.

Two of these four are also extremely blue:

48: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=182.94836038&dec=34.14759077&scale=0.2008&width=200&height=200) 33: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=50.12410042&dec=0.5315734&scale=0.1728&width=200&height=200)

The other two (of the four which fail both):

25: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=209.49237884&dec=14.909207&scale=0.2012&width=200&height=200) 52: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=170.32225969&dec=19.67555086&scale=0.1972&width=200&height=200)

Both have prominent bulges, and #52 may be nearly edge-on (the inverse concentration index is not very reliable for edge-on spirals, or at least it needs to be applied somewhat differently, as a test).

So, what does all this mean, in terms of using multiple criteria to decide if these 23 are, in fact, spirals? That's the subject of my next post!  :-*

* using the criterion ">50% of votes for Spiral means the galaxy is a spiral"; or belong to the greater set, to use the Galaxy Zoo 1 Data Release (http://data.galaxyzoo.org/#zoo_1) term
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate June 30, 2012, 10:37:24 PM
How many of the spirals are "blue", have fDeV < 0.6, and inverse concentration indices > 0.385 (irrespective of whether there are 'close-in' blobs or not)?

Nine.

How many fail just one of these three tests?

Five.

How many fail two of these three tests?

Nine.

How many fail all three of these tests?

None.

Do any of the superclean spirals - those which every zooite agrees is a spiral - fail at least one of the three tests? Yes, one:

21: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2012&width=200&height=200) fDeV = 0.93

Leaving aside the extremely blue/nuclear starburst/AGNs (see below), how many of the spirals fail more than one test?

Four: #25, #52, #11, and #15.

How many of the nine which pass all tests are clean?

Six.

How many clean spirals fail at least one test?

Three: #21 (unanimously a spiral  ::)), #11, and #15 (both these fail the color test)

Combining all these, is there a reasonable-seeming way to weight each test (including that of zooite votes), to put objects into three buckets, which we might call "confirmed spirals", "probable spirals", and "possible spirals"?

I've got my own ideas, but what do you think?

Extremely blue/nuclear starburst/AGNs: here are the spectra of the five bluest, from bluest to reddest:

31: (http://skyserver.sdss.org/public/en/get/specById.asp?id=503229708788301824)
48: (http://skyserver.sdss.org/public/en/get/specById.asp?id=562898273568817152)
49: (http://skyserver.sdss.org/public/en/get/specById.asp?id=139553400911036416)
55: (http://skyserver.sdss.org/public/en/get/specById.asp?id=699698001743970304)
33: (http://skyserver.sdss.org/public/en/get/specById.asp?id=116472200868921344)

AGNs/nuclear starbursts wreck havoc with classification systems, don't they?

But what about the next bluest spiral? Is that, perchance, also an AGN/nuclear starburst galaxy? Is it one which fails any test too? Here it is:

25: (http://skyserver.sdss.org/public/en/get/specById.asp?id=772318901919809536)

Next: are there any 'spirals', among the galaxies zooites classified as something other than spiral (or which they could not make up their minds about)? I.e. are there any 'false negatives'?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate July 01, 2012, 01:32:58 AM
30 objects are not greater spirals.

Of these, four are extremely blue, so may be AGN/starburst nuclei galaxies, and so classification may be messed up; put these to one side (for now): #10, #45, #53, and #54.

Of the remaining 26, six are 'blue' (i.e. obviously fail the LRG color cut), and another four marginal: #06, #24, #27, #39, #46, and #57; #28, #34, #40, and #41.

Of the 26, four have inverse concentration indices suggesting they may be spirals: #28, #34, #57, and #58.

Of the 26, five have fDeV values < 0.6: #06, #41, #42, #56, and #57.

So, one of the 26 meets all three tests for being spiral:

57: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=190.51568591&dec=25.58472112&scale=0.2012&width=200&height=200)

Four more meet two tests (three only just; the colors are marginal):

06: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=203.70982402&dec=10.00969496&scale=0.2&width=200&height=200)
28: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=27.58864136&dec=-10.09181444&scale=0.1976&width=200&height=200) 34: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=240.75416488&dec=37.1463647&scale=0.1895&width=200&height=200) 41: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=176.01918218&dec=30.31833247&scale=0.1953&width=200&height=200)

Considering only #06 and #57 as possible false negatives, how are the zooite votes distributed? Both have ~45% for Overlap/Merger, and Spiral as the next highest tally (45% for #57, 31% for #06). That suggests that, if the choices offered had been expanded to include "Merger/Overlap, at least one object being a Spiral", one of both of these might be clean, possibly superclean!

The four extremely blue galaxies, from bluest to reddest:

53: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=148.90165145&dec=54.24971365&scale=0.1859&width=200&height=200) 10: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=233.22409237&dec=30.34983327&scale=0.1788&width=200&height=200)
45: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=160.35679767&dec=13.41624757&scale=0.1754&width=200&height=200) 54: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=218.79291943&dec=8.71874255&scale=0.1788&width=200&height=200)

And their spectra, in the same order:

53: (http://skyserver.sdss.org/public/en/get/specById.asp?id=216678809057886208)
10: (http://skyserver.sdss.org/public/en/get/specById.asp?id=390915412579057664)
45: (http://skyserver.sdss.org/public/en/get/specById.asp?id=492528902128795648)
54: (http://skyserver.sdss.org/public/en/get/specById.asp?id=510263708031647744)

Yep, three of these four have their classifications messed up by their intense emission line nuclei; how to explain #45? Its nucleus does seem bright and star-like, but its spectrum is nothing to write home about.

Ignoring the spectrum, and judging these four by the three tests, how do they fare (other than being blue)? #10 would be a spiral (it passes both other tests, with ease), but all the others fail all the (other) tests.

Combining all these, together with results presented in the last post, is there a reasonable-seeming way to weight each test (including that of zooite votes), to put objects into three buckets, which we might call "confirmed spirals", "probable spirals", and "possible spirals"?

Next: the "distant" and "spiral" parts have been dealt with; what about the "giant" one?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate July 02, 2012, 04:22:34 PM
But are any of these 23 spirals truly giants?  ??? And what is a giant spiral anyway?  ??? ??? Even more fundamentally, how do you measure the size of a spiral galaxy?  ??? ??? ???

Start with the last question first. It has been known for some time that most spiral galaxy disks have an 'exponential profile' (see the You Have GOT To Be Kidding Me! (http://www.galaxyzooforum.org/index.php?topic=280195.0) OOTD for more details), and the SDSS photometric pipeline conveniently outputs values for the 'effective radius' (in arcseconds) of fitted exponential profiles (one for each band). So, as a rough and ready measure, I'll take those values, for the g band*.

This would be pretty good, so it would seem, for face-on spirals with no bars and with tiny, almost invisible bulges (and nuclei). It won't work at all for those with bright AGNs/nuclear starbursts. Also, what effect do things like viewing the spiral at a significant angle (like M31/the Andromeda galaxy) have, and the presence of blobs? With a software tool such as GALFIT (http://users.obs.carnegiescience.edu/peng/work/galfit/galfit.html), most of these complications could be addressed (and I plan to download, and learn how to use GALFIT, now that I have a LINUX PC), but that's some fun for a later time.

A way to sidestep all this complication - to a large extent - is to use another set of outputs from the SDSS pipeline, the "Isophotal Quantities (http://cas.sdss.org/astrodr7/en/help/docs/algorithm.asp#photo_iso)" (isophote: "(Astronomy) a line on a diagram or image of a galaxy, nebula, or other celestial object joining points of equal surface brightness", source (http://www.thefreedictionary.com/isophote)):

: SDSS DR7 SkyServer
Isophotal Quantities

A second measure of ellipticity is given by measuring the ellipticity of the 25 magnitudes per square arcsecond isophote (in all bands). In detail, frames measures the radius of a particular isophote as a function of angle and Fourier expands this function. It then extracts from the coefficients the centroid (isoRowC,isoColC), major and minor axis (isoA,isoB), position angle (isoPhi), and average radius of the isophote in question (Profile). Placeholders exist in the database for the errors on each of these quantities, but they are not currently calculated. It also reports the derivative of each of these quantities with respect to isophote level, necessary to recompute these quantities if the photometric calibration changes.

In particular, a measure of the size of a galaxy is "isoA_r", the length (in arcseconds) of the semi-major axis of the ellipse fitted to the 25 magnitudes per square arcsecond r-band isophote. This, of course, has problems of its own, not least of which is that "The model fits [that includes the effective radius of fitted exponential profiles] do correctly account for the effect of the seeing, while the methods presented here do not [i.e. the isophotal quantities do not account for the effects of seeing]." But, once again, without something like GALFIT, this should serve well enough.

In the following I'm going to leave out #04; it's such a wild object none of the metrics would seem to make much sense (but it is BIG!).

The galaxy with the biggest physical disk is #07 (i.e. translating arcseconds to kpc, using the redshift and Ned Wright's online Javascript Cosmology Calculator (http://www.astro.ucla.edu/~wright/CosmoCalc.html)), its effective radius is ~31 kpc. The two smallest are #25 and #25, at ~7 kpc:

07: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=116.47419608&dec=40.99362399&scale=0.1597&width=200&height=200) 25: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=209.49237884&dec=14.909207&scale=0.2012&width=200&height=200) 52: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=170.32225969&dec=19.67555086&scale=0.1972&width=200&height=200)

For the following, the g-band effective radii are between 20 and 30 kpc (in order, biggest first): #05, 15, 03, 01, 11, and 13. All the other spirals (except those with AGNs/nuclear starbursts) have effective radii between 10 and 20 kpc.

Using the major axis r-band isophote measure, the biggest is #11 (a whopping ~147 kpc!  :o), and the smallest #55 (~65 kpc - no reason not to use this measure with AGN/nuclear starburst galaxies) and #25 (~73 kpc):

11: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.2008&width=200&height=200) 55: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=165.33109844&dec=17.65911684&scale=0.2012&width=200&height=200) 25: (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=209.49237884&dec=14.909207&scale=0.2012&width=200&height=200)

Four other galaxies have r-band major axes > 100 kpc (in descending order): #15, 07, 13, and 05. In addition to #55 and 25, three others have r-band major axes < 80 kpc (also in descending order): #31 (just below 80), 49, and 09.

Given all this - and if you'd like the full set of 'size' measures, PM me - how do you think we should set the minimum, for a distant spiral to be called 'giant'?

To help you ponder this question, check out the Figure 6. I copied in the stacks and stacks of galaxies (http://www.galaxyzooforum.org/index.php?topic=279000.0) OOTD. For example, very approximately, how many of the 23 spirals would be significantly larger (at the 25 mag r-band isophote) than the average LRG?

For fun, I tried to make an ellipse of approximately the size of the 25 mag r-band isophote, of #11, and superimpose that on an image of M31 (taken from Google Sky (http://www.google.com/sky/)). I wasn't very successful (if you put a ruler over this, you'll see all kinds of problems  :P  :(), but visually it's a good indication:

(http://i888.photobucket.com/albums/ac85/JeanTate/M31plus11.jpg)

One more post to go: completeness and contamination.

* why the g-band? why not the r-band? It's complicated, but as bulges and bars are (almost always) redder than disks, the g-band fitted exponential profile is more likely to trace the disk than the r-band one. Ideally the u-band would be better, but most u-band images (at least of these galaxies) are too noisy to permit reliable profile fitting. When it comes to galaxies with redshifts > 0.4, it may be that we'd need to move one band to the red; I'll look into that later.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate July 03, 2012, 12:57:50 AM
How many giant, distant spirals are there, in the SDSS footprint?

Let's see ...

I have ~200 z > 0.4 SDSS DR7 candidates, with spectra, from a relatively simple Casjobs SQL Search I did. Assume 40% of those turn out to be giant, distant spirals (i.e. that are are approximately as many, proportionately, as there are among the ~50 examined so far); that makes ~80.

What about those with redshifts greater than 0.3 but less than 0.4? Well, for every 1 LRG (Luminous Red Galaxy) in DR7, selected via Cut II, there are ~5 selected via Cut I: "The two cuts together result in about 12 LRG targets per deg2 that are not already in the main galaxy sample (about 10 in Cut I, 2 in Cut II)" (source (http://cas.sdss.org/astrodr7/en/help/docs/algorithm.asp#lrg))*. If giant spirals are distributed much the same way, that means ~400.

What about DR8? I need to check, but the DR8 sky coverage added ~100% to that of DR7. That leads to an estimate of ~800.

But that's only those with spectra; what about those, in the DR8 SDSS footprint, without spectra? For example, the galaxy Els posted so long ago, and which Budgieye re-posted back on page 1 of this thread?

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=147.98732241&dec=11.73666711&scale=0.2&width=200&height=200)

At this stage I have no way of even beginning to make an estimate; let's say - conservatively - that there's at least another 100%. We're up to ~1,600. 8) Which is about the number of overlaps, in the Galaxy Zoo-based overlaps catalog (http://data.galaxyzoo.org/overlaps.html)!  :o

There are considerable challenges to finding these ~1,500 giant, distant spirals. And classifying good candidates is, perhaps, the easiest part (it's certainly the most enjoyable part!).

To get the 53 candidates, I started with ~240 objects, from the simple Casjobs SQL Search I ran. Here are three examples of objects that I quickly rejected:

(http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=199.89733297&dec=33.18685329&scale=0.2&width=200&height=200) (http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=314.16580654&dec=0.8473987&scale=0.2&width=200&height=200) (http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=44.57583906&dec=0.825308&scale=0.2&width=200&height=200)

DR7 ObjIds: 587739302611845223 (a galaxy ~15" in radius, with a z of 0.371  ::)), 587730848498516094 (~11", z=0.409; there might be spiral here, but how could you ever tell?), and 587731513690816823 (~11", z=0.393; the redshift is wrong, this is a local dwarf), respectively.

Some others were more difficult to cull; for example:

(http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=213.53898347&dec=54.77044988&scale=0.2&width=200&height=200) (http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=159.49514647&dec=5.4200853&scale=0.2&width=200&height=200) (http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=222.97406349&dec=29.91395111&scale=0.2&width=200&height=200)

587735666916720976 (an overlap; there might be a z=0.380 giant spiral behind this local dwarf), 587728881416405041 (a very strange spectrum - see below - but it's not that of a z=0.380, edge-on spiral), and 587739408406872152 (almost certainly a giant, z=0.368 galaxy, and possibly a spiral too), respectively.

There are ~30 of these, 'close call' objects; suppose some of them are truly giant, distant spirals, how does that affect my estimate of the total? And should we not reject them? What do you think?

But why does it matter anyway? I mean, who cares if there are, in fact, a dozen or so (or even a hundred or so) giant, distant spirals hidden in the glare of a bright foreground star (etc)? For some science goals of doing research like this, yes, it does matter; and at least some astronomers do care.  :o  ;D

(http://skyserver.sdss.org/public/en/get/specById.asp?id=162635978010263552)

* ignore those "already in the main galaxy sample", for now at least.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: LankyYankee July 23, 2012, 04:52:24 PM
Here is (probably) another VERY big spiral that's (probably) far away, but not super far away.

(http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=131.85852793&dec=53.63756273&scale=0.19806&width=512&height=512&opt=&query=)

It's MCG +09-15-023  1237651192432427052 (http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237651192432427052). We don't have its redshift, the it certainly appears to be interacting with galaxy at 10:00, which is SDSS J084730.04+533836.3  1237651192432427053 (http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237651192432427053) z=0.114
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate August 09, 2012, 08:49:27 PM
Thanks again, LankyYankee!  :-*

Yes, that too is a ginormous spiral (assuming it does have a redshift of ~0.114).

I've been trying to find a way to show how huge these galaxies are, compared with the 'run of the mill' ones zooites classified, back in the original Galaxy Zoo. One difficulty I've had - now pretty much solved (I hope  ;)) - is on show in this thread (http://www.galaxyzooforum.org/index.php?topic=280329.0).

Anyway, here's the third image from Figure A3, extended, in the Bamford et al. (2008) paper, "Galaxy Zoo: the dependence of morphology and colour on environment" (link to arxiv preprint (http://arxiv.org/abs/0805.2612))

(http://i888.photobucket.com/albums/ac85/JeanTate/A3cBamford.jpg)

What does the figure show? Here's my interpretation: all the galaxies used in the original Galaxy Zoo, with redshifts between 0.14 and 0.15, put into little bins. For each galaxy, the physical size and actual brightness were worked out, assuming certain cosmological parameters ('737 cosmology'), and then the galaxies were put into bins. In each bin the color represents the ratio of the number of ellipticals [1] to spirals, where the kind of galaxy ("morphological type") was "de-biased" (i.e. the actual kind of galaxy estimated from the distribution of zooites' votes, using the technique described in the paper; this attempts to account for the fact that a small, distant spiral will look like an elliptical, for example). A yellow bin means there are ~100 ellipticals for every spiral; a deep blue one, ~100 spirals for every elliptical. The dotted lines show the limits of the selection; below the horizontal one, galaxies are too small; to the right of the vertical one, too faint (full caption below).

Anyway, the main point of my graphic is the four black dots well above the Figure A3 chart. Each represents a giant spiral, at the location on the absolute size-luminosity chart corresponding to its estimated actual physical size and brightness [2]

From top to bottom these spirals are: NGC 1262 (almost literally 'off the chart'!  ::) ), #11, #03, #21 (see images below; the pixel scale is 0.39").

Yes, these galaxies are extraordinarily big, and bright.

Full  caption (the other two images are for redshift ranges 0.03 < z < 0.04 and 0.08 < z < 0.09)
: Bamford et al.(2008)
Figure A3. Ratio of the early-type to spiral measured type likelihoods as a function of absolute magnitude and physical size, for galaxies in three example redshift bins. The logarithmic colour scale is shown by the bar on the right. The dotted lines indicate the r = 17.77 apparent magnitude limit, μ50,r = 23 mag arcsec−2 apparent surface brightness limit, and the physical scale corresponding to an angle of 1 arcsec, at the central redshift of each bin.

(http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=48.88992096&dec=-15.87930403&scale=0.39&width=200&height=200&opt=&query=)
NGC 1262

z = 0.116

Mr = -24.9

R50 = 26.1 kpc
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=199.5481415&dec=62.28281665&scale=0.39&width=200&height=200)
#11 (DR7 ObjId 588011219134054611)

z = 0.306

Mr = -24.1

R50 = 21.2 kpc
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.39&width=200&height=200)
#03 (DR7 ObjId 587736618787602957)

z = 0.390

Mr = -23.9

R50 = 19.8 kpc
(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.39&width=200&height=200)
#21 (DR7 ObjId 587727225690063043)

z = 0.305

Mr = -23.6

R50 = 15.8 kpc

[1] actually, 'early-type galaxies'; no attempt was made to separate ellipticals from lenticulars

[2] Strictly speaking not exactly. Bamford et al. removed Galactic extinction and applied a k correction; I have not tried to do that for these four galaxies (for more details see this thread (http://www.galaxyzooforum.org/index.php?topic=280329.0)).
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: zutopian August 12, 2012, 08:42:31 PM
(http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=120.47225387&dec=34.59045882&scale=0.19806&width=200&height=200&opt=&query=)
http://skyserver.sdss.org/dr7/en/tools/explore/obj.asp?id=587731873923465772
z=0.283
2-armed spiral
Merger?
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate September 17, 2012, 03:15:07 PM
Thanks zutopian!  :-*  8)

That is, indeed, a terrific example of the kind of galaxy a bunch of us zooites is hunting  :) ... except that its redshift is just a tad too low  :(

Or perhaps not. Whatever we end up doing, in the Hudsmania (Huge distant spiral -mania, get it?!) project, it may be necessary (or at a Very Good Idea) to get a handle on giant (spiral) galaxies in the SDSS at lesser redshifts (thank you ngc3314 and klmasters for your help and advice).
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate September 24, 2012, 01:00:44 PM
I've been looking for giant spirals that are not so distant (i.e. z < 0.3), but also not all that close either (I chose z > 0.14). My first search was in DR7, and limited to galaxies with spectroscopic redshifts. Here is a sample of what I found:

(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=37.3085&dec=0.573709&scale=0.20&width=250&height=250)
SDSS J022914.02+003425.3 588015509822570632 (http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=588015509822570632)

ra = 37.30846, dec = 0.57371

zsp = 0.153 +/- 0.00010

R50(r) = 7.32"
R50 = 19.1 kpc
(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=56.5126&dec=1.00178&scale=0.20&width=250&height=250)
SDSS J034603.01+010006.4 588015510636265731 (http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=588015510636265731)

ra = 56.51256, dec = 1.00178

zsp = 0.186 +/- 0.00012

R50(r) = 5.87"
R50 = 18.0 kpc
(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=182.419&dec=21.6558&scale=0.20&width=250&height=250)
SDSS J120940.47+213920.7 587742060535087155 (http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587742060535087155)

ra = 182.41863, dec = 21.65575

zsp = 0.213 +/- 0.00016

R50(r) = 6.65"
R50 = 22.7 kpc
(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=249.941&dec=46.1517&scale=0.20&width=250&height=250)
SDSS J163945.95+460906.1 587725994110681526 (http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=587725994110681526)

ra = 249.94148, dec = 46.15170

zsp = 0.247 +/- 0.00016

R50(r) = 5.72"
R50 = 22.0 kpc
(http://casjobs.sdss.org/ImgCutoutDR7/getjpeg.aspx?ra=179.898&dec=12.952&scale=0.20&width=250&height=250)
SDSS J115935.42+125707.3 588017567098208464 (http://cas.sdss.org/dr7/en/tools/explore/obj.asp?id=588017567098208464)

ra = 179.89761, dec = 12.95204

zsp = 0.263 +/- 0.00016

R50(r) = 5.08"
R90(r) = 20.6 kpc
(http://skyservice.pha.jhu.edu/DR7/ImgCutout/getjpeg.aspx?ra=194.28709396&dec=5.17346135&scale=0.20&width=250&height=250)
SDSS J125708.90+051024.4 587729159503086233 (http://skyserver.sdss.org/public/en/tools/explore/obj.asp?id=587729159503086233)

ra = 194.28709, dec = 5.17346

zsp = 0.252 +/- 0.00020

R50(r) = 4.17"
R50 = 16.3 kpc

I used '71/27/73 cosmology' to estimate the R50 in kpc, which is a bit different than Bamford et al. (2008) used (theirs is a 737 cosmology).

Clearly, large spirals can be found, in DR7, at redshifts from ~0.15 to at least 0.4 (though none seem as large as NGC 1262 or MCG +09-15-023; perhaps their redshifts are a fair bit less than ~0.115?).

The last galaxy - an Eos (edge-on spiral, not the goddess of dawn!) - points to a possible selection bias: if such galaxies were face-on, would they have larger observed R50(r)? More practically, is there a way to use B/A (the ratio of the length of the minor axis to that of the major axis) to 'correct' for inclination? And if so and if one were to re-do the search I just did, would this part of extra-galactic astronomy see the dawning of the Age of AquarEos?  :o  ::)  :D

UPDATE: "Aquarius Eos" -> "AquarEos" (must not have finished my coffee when I wrote that first time; how could I have missed it??  :P)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: zutopian September 25, 2012, 06:48:56 AM
I found the topic:"Distant spiral with z=0.475?", which was started on September 04, 2007:
http://www.galaxyzooforum.org/index.php?topic=6390.msg44381#msg44381

In that topic a DR7 image was posted. I post the corresponding DR8 image here, because in this case, the DR8 image is better.
I would say, that it is indeed a spiral! The spectrum chart says z=0.475!

(http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=209.26883&dec=34.30475&scale=0.19805&width=212&height=212&opt=&query=) (http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=209.26883&dec=34.30475&scale=0.19805&width=212&height=212&opt=I&query=&InvertImage=on)
http://skyserver.sdss3.org/dr8/en/tools/quicklook/quickobj.asp?id=1237662683606483541

EDIT:

I can see two arms and called it counter-clockwise.
Above comment is from that old topic.
My comment:
On the DR7 image I can't see that, but after looking at the DR8 image, I agree!

: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate September 25, 2012, 07:17:11 AM
I found the topic:"Distant spiral with z=0.475?", which was started on September 04, 2007:
http://www.galaxyzooforum.org/index.php?topic=6390.msg44381#msg44381

In that topic a DR7 image was posted. I post the corresponding DR8 image here, because in this case, the DR8 image is better.
I would say, that it is indeed a spiral! The spectrum chart says z=0.475!

(http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=209.26883&dec=34.30475&scale=0.19805&width=212&height=212&opt=&query=) (http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=209.26883&dec=34.30475&scale=0.19805&width=212&height=212&opt=I&query=&InvertImage=on)
http://skyserver.sdss3.org/dr8/en/tools/quicklook/quickobj.asp?id=1237662683606483541

Wow!  :o  8)

Thank you zutopian  ;D  :-*

For this object, R50(r) is 3.61", which makes R50 ... (calculate, where's Ned's cosmocalculator? calculate) ... 21.2 kpc. That's BIG  :D

To answer fluffy's question:
i cant see any arms  :(
the green stuff is the arms.

Oh, and fracDeV_r is 0.56 (which means it likely has an exponential profile, which is what most spirals have), and the r-band inverse concentration index is 0.52, which is well and truly into 'spiral' territory. I haven't checked the colors, but I'd be astonished if they were typical of LRGs.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: zutopian September 25, 2012, 07:49:04 AM
I edited my post.: I added a comment.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: zutopian September 25, 2012, 10:10:11 AM
I suggest, that you present that spiral in a new OOTD.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: zutopian September 25, 2012, 10:18:07 AM
I deleted following post.:
Here is another spiral with z>0.4.: I copied following post from the topic "Biggest redshift".:
...

I deleted it, because I found out, that it has a low zconf in DR7 and in DR8 it has z=0.079.
Anyway. You should check that topic for other distant spirals. I saw some with z>0.3!
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: LankyYankee October 08, 2012, 09:12:42 PM
(http://skyservice.pha.jhu.edu/DR9/ImgCutout/getjpeg.aspx?ra=188.7521048731816&dec=50.85112464&scale=0.149806&width=612&height=412&opt=&query=)

MCG +09-21-022  1237661152450248784 (http://skyserver.sdss3.org/dr9/en/tools/explore/obj.asp?id=1237661152450248784) (right)
SDSS J123503.39+505049.1  1237661152450248787 (http://skyserver.sdss3.org/dr9/en/tools/explore/obj.asp?id=1237661152450248787) (lower left) both z=0.227

I just posted these in the collisional rings thread. I'm adding it here because MCG +09-21-022 appears to me to be at least an order of magnitude larger that a typical large spiral.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate October 08, 2012, 10:29:28 PM
Interesting, thank you LankyYankee.  :)  8)

Where did you get the redshift for MCG +09-21-022? It certainly doesn't seem to have the colors of a galaxy with a z of > 0.2, and the SDSS Photoz is only 0.093 (which seems about right, color-wise).
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: LankyYankee October 08, 2012, 10:42:47 PM
If you go to 1237661152450248784 (http://skyserver.sdss3.org/dr9/en/tools/explore/obj.asp?id=1237661152450248784) and then click on NED search, the listed redshift z=0.2267. If someone were to discover the listing is wrong, that it ought to read, say, z=0.022, I wouldn't be very surprised, because it sure doesn't have the appearance of being at that extreme distance.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate October 24, 2012, 05:05:40 PM
If you go to 1237661152450248784 (http://skyserver.sdss3.org/dr9/en/tools/explore/obj.asp?id=1237661152450248784) and then click on NED search, the listed redshift z=0.2267.
Thanks.

From there, I found that the source, for the redshift, is "The UNAM-KIAS Catalog of Isolated Galaxies" (the arXiv abstract is arXiv:1005.1571 (http://arxiv.org/abs/1005.1571)).

I was unable to find the full "Table 1", which contains the galaxy and its redshift. However, as there is no SDSS redshift for this galaxy, it might be pertinent to look at what the paper says about how they obtained redshifts in such cases:

: Hernández-Toledo et al.
Of the sample, approximately 6% lack measured redshifts because of fiber collisions, are
assigned the spectroscopic redshift of the nearest neighbor, and are kept in our parent galaxy catalog. The isolated galaxies in our catalog are restricted to those with measured redshifts. However, we included galaxies with borrowed redshifts when the neighbors are searched to determine isolation of the target galaxies. This primary sample effectively has a magnitude range of only about 3.1 mag, which significantly limits the number of candidate isolated galaxies. To extend the range of magnitude, we attempt to include the bright galaxies with r < 14.5. However, the spectroscopic sample of the SDSS galaxies is not complete for rPet < 14.5. We thus searched for the various literature to borrow redshifts of the bright galaxies without SDSS spectra to increase the spectroscopic completeness.

So, what "various literature" did they search, to get the "borrowed redshift" of MCG +09-21-022? I don't know. But as SDSS J123503.39+505049.1 has a measured redshift, and as the redshift of MCG +09-21-022 could not have been obtained by SDSS (due to "fiber collisions"), it might be that it is "the nearest neighbor", and so its "borrowed redshift" is that of SDSS J123503.39+505049.1.

If someone were to discover the listing is wrong, that it ought to read, say, z=0.022, I wouldn't be very surprised, because it sure doesn't have the appearance of being at that extreme distance.
If what I found is correct, it's not so much that there's a misprint; rather, it's that the method for allocating a redshift to
MCG +09-21-022 was flawed.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate November 21, 2012, 09:38:38 PM
I know that NGC 1262 here isn't exactly what you're looking for because it's too close to us at z=0.116, but assuming its redshift is correct, it is a VERY big spiral, so I thought I'd mention it to the the giant spiral hunters.

(http://skyservice.pha.jhu.edu/DR8/ImgCutout/getjpeg.aspx?ra=48.88992096&dec=-15.87930403&scale=0.1980635&width=512&height=512&opt=&query=)

1237667244335038577 (http://skyserver.sdss3.org/dr8/en/tools/explore/obj.asp?id=1237667244335038577)

I'm not sure when it was added, but NED has this, on NGC 1262:
: NED
ESSENTIAL NOTE for NGC 1262:

Da Costa, et al. (1998,AJ,116,1) give v = 24977 +/- 51 km/sec.

That's a z of 0.0833, at which the scale is 1.547"/kpc (per Ned Wright's CosmoCalc (http://www.astro.ucla.edu/~wright/CosmoCalc.html), with his default values). R50 would be 'only' 19.4 kpc (instead of 26.1 kpc), making NGC 1262 pretty big, but not as big as #03.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate March 07, 2014, 07:44:57 PM
Maybe I'm getting paranoid, but just in case the plug gets pulled on Letters*, I'd like to post - here - a Letter I wrote on these giant, distant spirals. That way if, some day, a preprint appears in arXiv, on giant, distant spirals, there'll be a public record of my previous work on this topic.

: Jean Tate (29 JUNE 2012)
Discovery of Four Giant, Distant Spirals

Summary

I report the discovery of four spiral galaxies in SDSS DR7, at z > 0.3, each with an effective radius exceeding 20 kpc.

1. Introduction

Among the spirals in D.L. Block's 1984 A photographic atlas of primarily late type spirals printed as if each galaxy were at the same distance (http://adsabs.harvard.edu/abs/1984papl.book.....B), the two largest in the SDSS DR7 footprint are NGC 309 and NGC 3646 (Keel, 2009 (http://www.galaxyzooforum.org/index.php?topic=276492.0)). NGC 309's disk has a SDSS g-band effective radius of 9.5 kpc given its observed redshifts (from NED (http://ned.ipac.caltech.edu/), 0.0178), that it is in the Hubble flow, and generally accepted values for the various cosmological parameters [1]; from Laurikainen et al., 2004 (http://adsabs.harvard.edu/abs/2004MNRAS.355.1251L), NGC 3646's disk has a effective scale length of 7.8 kpc (deprojected), given the same assumptions and a redshift of 0.0142 (also from NED) [2]

This Letter briefly describes four recently discovered giant, distant spiral galaxies in SDSS DR7 (http://www.sdss.org/dr7/), and compares them with NGC 309 and NGC 3646.

The rest of this Letter is structured as follows: 2, the Data and Images; 3, Analyses; 4, Discussion; 5, Conclusion. Appendix A contains details of the 'zooite voting' method.

Due to the current limitations of Letters, several typographic and formating conventions commonly used in journals such as ApJ and MNRAS have not been used.

2. Data and Images

Values for key observational parameters, from SDSS, for the four giant, distant spirals are given in Table 1.

(http://i888.photobucket.com/albums/ac85/JeanTate/Letter003T1.gif)

Table 1. SDSS data on the four giant, distant spirals. Column headings petroRad(r), fracDeV(r), expRad(g), and expAB(r) are the same as in the SDSS DR7 PhotoObj; c(r) is the inverse concentration ratio in the r-band (i.e. petroR50(r)/petroR90(r)).

Images of these four giant, distant spirals are given in Fig. 1; each is derived from the SDSS DR7 Explore image (http://skyserver.sdss.org/public/en/tools/chart/), re-scaled to be 180 kpc x 180 kpc, using the SDSS DR7 redshift and generally accepted values for the various cosmological parameters [1], derived using Ned Wright's online cosmomology calculator (http://www.astro.ucla.edu/~wright/CosmoCalc.html).

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=19.49383773&dec=-8.9779174&scale=0.1876&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=239.46824854&dec=27.51376847&scale=0.1724&width=200&height=200)

(http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=217.38945795&dec=30.50017047&scale=0.1976&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=359.85480682&dec=-10.43578329&scale=0.2012&width=200&height=200)

Figure 1. Optical images of the four giant, distant spirals, a combination of the g, r, i filters according to the SDSS DR7 data. Each image is 180 kpc x 180 kpc (see text for details). Top row, left to right: J0117-0858, J1557+2730. Bottom row, left to right: J1429+3030, J2359-1056

3. Analyses

3.1 Are these four galaxies spirals?

Applying the Eisenstein et al. 2001 (http://arxiv.org/abs/astro-ph/0108153) Luminous Red Galaxy (LRG) criteria (Cut I, as all four galaxies have z <~0.4): all satisfy every criterion but one; all four galaxies fail the first criterion, they are too blue. Consequently, they do not have the GALAXYRED flag set, in PrimTarget.

The SDSS DR7 SkyServer (http://cas.sdss.org/astrodr7/en/help/docs/algorithm.asp) suggests using fracDeV(r), the fractional likelihood of a deVaucouleurs profile, in the r band, as a means of classifying objects; specifically, if fracDeV(r) < 0.5, an object that is obviously a galaxy would, generally, be a spiral. Three of the four galaxies have fracDeV(r) < 0.5 (see Table 1). The fourth, J2359-1026, has a fracDeV(g) value of 0.3831, which may be consistent with Masters et al., 2010 (http://arxiv.org/abs/1001.1744) and Masters et al., 2010 (http://arxiv.org/abs/1003.0449), who found that the DR7 photometric pipeline tends to "home in" on the bulge of spirals with prominent bulges and bars, resulting in a fracDeV(r) > 0.5 for these spirals. It should also be noted that, for J2359-1026, petroR50(r) (the radius, from the photocenter, within which 50% of the r band light of the object is distributed) is considerably smaller than petroR50(g) (ditto, for the g band) - 3.51" vs 4.12".

Following Masters et al., 2010 (http://arxiv.org/abs/1001.1744), based in turn on Strateva et al., 2001 (http://arxiv.org/abs/astro-ph/0107201) and Shimasaku et al., 2001 (http://arxiv.org/abs/astro-ph/0105401), an inverse concentration index of 0.385 can be used as a threshold for separating spirals from ellipticals and lenticulars. All four galaxies are spirals, by this criterion.

There can be no doubt that, by visual inspection of the SDSS Explore image, J2359-1026 is, morphologically, a spiral galaxy: it has two very well-defined, rather loose anti-clockwise arms emerging from opposite ends of a reasonably well-defined bar.

For the other three galaxies it is not immediately obvious, from visual inspection, that they have a spiral galaxy morphology. I invited zooites – members of the Galaxy Zoo forum (http://www.galaxyzooforum.org/index.php) – to classify ~50 z > 0.3 galaxies, from their SDSS DR7 Explore images, including these four. The process was rather informal, especially at the start, but most zooites who classified these images did so in response to a series of Private Messages (for details, see Appendix A).

The results were unanimous; every one of the zooites classifed each of the four galaxies as "spiral". The number of zooite votes ranged from 19 (for J1557+2730, and J2359-1026) to 15 (for J1429+3030), and 14 (for J0117-0858).

3.2 How big are these spirals?

Table 2 contains estimates of the effective radii of each of the four spirals. These are derived using the PhotoObj values for expRad(g) (i.e. the effective radius, in the g band, for the fitted exponential profile), in arcseconds, and the equivalent physical value in kpc, assuming generally accepted values for the various cosmological parameters [1]. These are "as is"; no attempt has been made to 'deproject', to adjust for inclination (in any case, the SDSS photometric pipeline's estimates of inclination – expAB(r), see Table 1 – suggest all spirals are very close to "face-on", except perhaps J2359-1026).

Values for NGC 309 and NGC 3646 are also given, to show that these four giant, distant spirals are considerably bigger than any in D.L. Block's 1984 Atlas (of those within the SDSS DR7 footprint); over twice as big. The comparisons are not, strictly speaking exact, however. For example, 7.8 kpc for NGC 3646 is a deprojected estimate in the 2MASS H-band, and no attempt has been made to take account of the effects of Tolman surface brightness dimming (if any).

(http://i888.photobucket.com/albums/ac85/JeanTate/Letter003T2.gif)

Table 2. Estimated effective radii of fitted exponential profile, in kpc, for the four giant, distant spirals

4. Discussion

J2359-1026 was discovered entirely by accident, while looking for a quite different kind of galaxy. It had not, apparently, been posted by any zooite, in the Galaxy Zoo forum, before 9 May, 2012. A quick SDSS DR7 Casjobs SQL Search (http://skyserver.sdss.org/public/en/tools/search/sql.asp) produced several hundred objects with somewhat comparable photometric pipeline values. From these ~50 were selected for most detailed investigation. Preliminary results suggest that ~half are also giant, z > 0.3 spirals. A somewhat more structured follow-up resulted in ~200 strong candidate giant, z > 0.4 spirals (also in DR7). Few, if any, of these have been flagged as LRGs.

A collaborative, online 'giant, distant spiral project' has begun, in the Galaxy Zoo forum, to search for, and classify SDSS DR8 z > 0.3 spiral galaxies of comparable size to the four reported here.

A catalog of such galaxies may prove useful in terms of testing galaxy formation models.

5. Conclusion

Four spiral galaxies have been discovered in the SDSS DR7 footprint, at z > 0.3, each with an effective radius of > 20 kpc. Initial follow-up investigations suggest that there are at least several hundred similar objects, in the SDSS DR8 footprint.

Acknowledgements

Special thanks to zooites Blackprojects, Bruno, Budgieye, djj, ElisabethB, Geoff, GStark, Half65, joinpep, jules, laihro, lizardly, Lovethetropics, LynnSeguin, Mukund Vedapudi, NGC3314, paulrogers, PeterD, Rick Nowell, and spiralmania for their 'zooite classification votes'.

Without the Galaxy Zoo forum, part of the Zooinverse (http://zooniverse.org/), this work would not have been possible; special thanks to zookeeperChris and zookeeperKevin for developing the site, and to zooite Alice for her work as moderator and her assistance.

Appendix A Classification by Private Message

Here is a typical Private Message (PM) sent to zooites who expressed an interest in classifying candidate z > 0.3 giant spiral galaxies. Note that, typically, more than one candidate was included in each PM (e.g. ten, in this PM); however, only one – J0117-0858 – is shown; "02" is the tag I used for J0117-0858. Also, the text of the PMs varied somewhat, from PM to PM.

= - = - = - = - = - start PM - = - = - = - = -

Today's selection is a bit bigger - ten - and includes some AGNs (or, perhaps, galaxies with significant star-forming activity in the central ~2"), as I have already confirmed from their spectra. So you will see some changes in colors, as well as - possibly - an effect on the apparent shape (the former is a well-known phenomenon; the latter, well, let's just say there's some on-going investigation).

No changes to the protocol this time: In this PM are ten more pairs of images of galaxies, at the same 900 pc = 1 pixel scale, with tags (two digit numbers). If you prefer to work from bigger, more 'blown up', images, simply click on a tag and work with the Navigate page which comes up.

Once again, the choices are Spiral, Elliptical, Merger/Overlap, Star/Artifact, and Don't Know; once again, if you'd like to be more descriptive, by all means please go right ahead!

02 (http://cas.sdss.org/dr6/en/tools/chart/navi.asp?ra=19.49383773&dec=-8.9779174) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=19.49383773&dec=-8.9779174&scale=0.1876&width=200&height=200) (http://casjobs.sdss.org/ImgCutoutDR6/getjpeg.aspx?ra=19.49383773&dec=-8.9779174&scale=0.1876&opt=I&width=200&height=200)

= - = - = - = - = - end PM - = - = - = - = -

[1] H0 = 71 km/s/Mpc, ΩM = 0.27, and ΩΛ = 0.73

[2] as measured in the 2MASS H-band

Seven comments have so far been written on this Letter, four of them mine:

: JeanTate (June 29, 2012)
Thanks Kevin. There are ~200 z>0.4 candidates from DR7 that are ready for checking; assume the same 5:1 ratio as for LRGs (Cut I:Cut II, per DR7 SkyServer), and as many new objects in DR8 as in DR7 => ~2,000 candidates. Of the ~50 initial candidates (of which the four in this Letter are but the most obvious spirals), perhaps a third are "probable" spirals (somewhat akin to GZ1 DR's "clean"), giving an estimate of ~700. Plus or minus ~30%. That's just those with spectra, in DR8. Several candidate giant, distant spirals have already been identified, with photozs > 0.3. It's impossible to say, at this stage, how many of these there might be ...

: JeanTate (November 16, 2012)
There's a big boo-boo: I did not convert the NGC 3646 disk's effective scale length of 7.8 kpc (from Laurikainen et al., 2004) to an effective radius! So the final entry in Table 2 should be 13.1 kpc (an effective radius of 1 is equal to a scale length of 1.678, for an exponential profile). Thanks Karen. The SDSS DR7 spectra all look pretty clean, to my inexperienced eye. The template-fitting algorithm gives the best fit redshifts confidences of >0.96, and most of the major emission and absorption line identifications seem pretty secure (the H&K lines are pretty unambiguous in all but one of the spectra, to take just one example). Also, the synthetic DR7 colors look right, for galaxies with these redshifts (if you are ever looking for a new Zooniverse project, you could do worse than asking experienced zooites to estimate the redshifts of z>0.2 galaxies by their colors; I suspect you'd get results at least as good as the best photoZ pipelines, and better for outliers).

: JeanTate (April 29, 2013)
Thanks mjtbarrett. You may have heard about the mistake - which only recently came to light - that the economists Carmen Reinhart and Kenneth Rogoff made, involving the simplest of mistakes in a spreadsheet (if you haven't, google "Reinhart Rogoff excel error"). Well, while I don't use Excel (go Open Office!), I did make a pretty simple mistake! To get the "effective radius (kpc)" values in Table 2, for each of the HUDS, I had to multiply two numbers together: the value of expRad(g), expressed in arcsecs, from the SDSS database, and a scale factor, expressed in kpc per arcsec, from Ned Wright's Cosmology Calculator (http://www.astro.ucla.edu/~wright/CosmoCalc.html). So, for example, expRad(g) for J1557+2730 is 4.44", and the scale factor is 5.23; multiply those together and you get 23.2 (kpc), not 28.9 (I don't want to go into which two numbers I did, actually, multiply to get the values in Table 2; it's too embarrassing). To be continued ...

: JeanTate (April 29, 2013)
Continued... (comments have a hard upper limit on the number of characters, that's why I had to split mine into two). Here, then, are the values which *should* appear in Table 2, in the same order (top to bottom): 18.1, 23.2, 26.0, 19.5, 8.5 (yes, I got this one wrong too), and 11.7 (see my earlier comment, about confusing 'effective radius' with 'scale length').

* If you don't know about Letters, this post (http://www.galaxyzooforum.org/index.php?topic=281622.msg652459#msg652459) (and this one (http://www.galaxyzooforum.org/index.php?topic=281622.msg652664#msg652664) too) in a previous OOTD is a good introduction.
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: Hanny March 08, 2014, 09:01:30 AM
All fair enough and all that; people have started their more or less private posts (related to, of course) on here before, but - even though this might make things worse - do you know how easy it is for me or any of the other mods and admins to make this post or topic go away? I mean, I'm not going to, but, if you're being paranoid: why not start your own blog with this? Just saying. ;)
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: graham d March 08, 2014, 06:06:18 PM
SDSS is at the limit of its resolution here. The second galaxy is ringed without a spiral pattern I think. The first and third images may have some overlap features present rather than spirals. The fourth image is clearly spiral and there may be a bar(?).

Scientists can become very upset about any threat , intentional or not, about censorship even when it originates from a fellow scientist. Jean's comment is reallly a question and is rhetorical. Of course she is not paranoid; at least not more so than the average forum participant, and is never abusive. I've met a few famous scientists who truly were paranoid, part of the time at least. I knew one who when he got really really upset would throw himself on the floor and bite the carpet. Actually, I only saw him do it once but others attested to a few incidents that would be regarded as bizarre by non scientists. Paul Frampton is just about due for release this month?

http://www.nytimes.com/2013/03/10/magazine/the-professor-the-bikini-model-and-the-suitcase-full-of-trouble.html?pagewanted=all&_r=0
: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: mlpeck March 08, 2014, 07:13:41 PM
Maybe I'm getting paranoid, but just in case the plug gets pulled on Letters*, I'd like to post - here - a Letter I wrote on these giant, distant spirals. That way if, some day, a preprint appears in arXiv, on giant, distant spirals, there'll be a public record of my previous work on this topic.



Jean:

Why not get a free Authorea (https://www.authorea.com/) account and learn some LaTeX if you have ideas that you want to get into pixels? Their platform appears to be technically superior to Letters and there's little worry that it will go away anytime soon.


: Re: Wednesday, 16th May, 2012: Seeing Is Believing (Or Is It?)
: JeanTate March 12, 2014, 01:34:45 AM
Thanks Hanny, graham d, mlpeck.  :)

All fair enough and all that; people have started their more or less private posts (related to, of course) on here before, but - even though this might make things worse - do you know how easy it is for me or any of the other mods and admins to make this post or topic go away? I mean, I'm not going to, but, if you're being paranoid: why not start your own blog with this? Just saying. ;)

Even if, somehow, the entire Galaxy Zoo forum were to be taken down, what's here - in this thread at least - would be preserved in the Wayback Machine (http://archive.org/web/). If Letters - where my 'paper' was originally published - were to vanish, there'd be no trace of it in the Wayback Machine, because Letters is not, currently, public.

Maybe I'm getting paranoid, but just in case the plug gets pulled on Letters*, I'd like to post - here - a Letter I wrote on these giant, distant spirals. That way if, some day, a preprint appears in arXiv, on giant, distant spirals, there'll be a public record of my previous work on this topic.

Jean:

Why not get a free Authorea (https://www.authorea.com/) account and learn some LaTeX if you have ideas that you want to get into pixels? Their platform appears to be technically superior to Letters and there's little worry that it will go away anytime soon.

That's good advice. I've actually been thinking about doing that for some time ...  ;)