Author Topic: Artificially Redshifted and other new stuff  (Read 2338 times)

Notes

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Artificially Redshifted and other new stuff
« on: October 17, 2013, 12:50:19 pm »
Hullo folks
Starting to see a lot of new imagery coming through, which is all well and good, but because the nature of these images is very different to previous items it is sometimes difficult to use the 'default' answers as there is no button for 'none of the above'.  In particular are (apparently) close-up images of galactic centres, which make it extremely difficult to classify in terms of the number of spiral arms, brightness of the nucleus and even the basic shape.

Would appreciate some background explanation on this, in particular the stuff labelled 'artificially redshifted' - what's the significance of this?

ElisabethB

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Re: Artificially Redshifted and other new stuff
« Reply #1 on: October 17, 2013, 12:54:47 pm »
Everything is explained in this blog post : Galaxy Zoo continues to evolve

Notes

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Re: Artificially Redshifted and other new stuff
« Reply #2 on: October 17, 2013, 06:11:35 pm »
Thank you - that helps with the background but does not answer everything:

"... it is sometimes difficult to use the 'default' answers as there is no button for 'none of the above'.  In particular are (apparently) close-up images of galactic centres, which make it extremely difficult to classify in terms of the number of spiral arms, brightness of the nucleus and even the basic shape."

I feel the question 'trees' need re-examining, as on several occasions it is simply not possible to give a valid answer because none of the available answers apply.

planetaryscience

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Re: Artificially Redshifted and other new stuff
« Reply #3 on: October 18, 2013, 12:02:03 am »
I get that problem, too. However, my problems are on another thing:

How to classify faint Hubble blobs?
images such as these are hard to classify with the current tree. The main problem is the "features or disk" option is centered on spiral galaxies, and there should be a classification specifically for "features" such as rings, voorwerps, nebulae, and other odd objects.
I like to find asteroids and galaxy mergers- but all galaxies are still fine to me.

ElisabethB

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Re: Artificially Redshifted and other new stuff
« Reply #4 on: October 18, 2013, 06:53:27 am »
I get that problem, too. However, my problems are on another thing:

How to classify faint Hubble blobs?
images such as these are hard to classify with the current tree. The main problem is the "features or disk" option is centered on spiral galaxies, and there should be a classification specifically for "features" such as rings, voorwerps, nebulae, and other odd objects.

If I see a blob that is not smooth, I classify it as follows :

features or disk - edge on : no - bar : no - spiral : no - bulge : no - anything odd : no.

And I don't think the features or disk is centered on spirals. There's the fact that you have the option spiral = no.  ;D
« Last Edit: October 18, 2013, 11:45:11 am by ElisabethB »

ElisabethB

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Re: Artificially Redshifted and other new stuff
« Reply #5 on: October 18, 2013, 06:56:29 am »

"... it is sometimes difficult to use the 'default' answers as there is no button for 'none of the above'.  In particular are (apparently) close-up images of galactic centres, which make it extremely difficult to classify in terms of the number of spiral arms, brightness of the nucleus and even the basic shape."


Just classify what you see. If you don't see spiral arms, even if you think there are, just answer no. The classifications for these redshifted images are also used to see how our classifications can change with the distances we see galaxies.

Notes

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Re: Artificially Redshifted and other new stuff
« Reply #6 on: October 19, 2013, 08:52:43 am »
Thanks guys.  Planetaryscience I'm pretty sure there's a thread somewhere about Faint Hubble Blobs, but the fact is with FHBs we're looking at a whole bunch of 'cutting room floor' stuff which real astronomers simply don't have time to look at, so GZ is attacking the backlog in the hope of spotting the odd interesting image worth a closer look.  As ElisabethB says, if you can't make a proper ID, 'just say no' i.e. don't try to work out what it IS, say what it ISN'T.

...which is fair enough  :)

The problem with putting in buttons which say 'it's a voorwerp' or whatever is that people tend to see what they want to see when they don't know what it is.  It's bad enough already in chat where people are constantly hashtagging lenses, voorwerps and other stuff they think they see.  Our beloved moderator :-* spends half her time here telling noobies that what they think is a black hole is in fact a foreground star.  She must have the patience of a saint.

But among the latest stuff - mostly the artificially redshifted - the images don't relate well to the existing question tree, particularly if the image is apparently a 'close-up' where the outer structure of the object is lost outside of the frame.  Unfortunately not all of the images are even available in DR7 to give you a (belated) clue.  Take a look at http://talk.galaxyzoo.org/#/subjects/AGZ0007qqo and try to answer the questions.

OK so I will say 'no' to everything from now on, but what about brightness of the galactic nucleus?  The available responses (no bulge, obvious, dominant) do not apply.  In this case the nucleus (if that's what it is) is just barely visible - but this option has been removed.

For the record, I think I said:
has features
edge on? No (but it might be!)
bar?         No (but there might be!)
spiral?      No (but there might be!)
bulge?      No (but it isn't!)
oddities?  No (but hard to tell)

Over to the experts.