Warning: this topic has not been posted in for at least 120 days.
I copied below post from the another thread, because I think, that it should be also here.:
I read today the blog "The Finale of Merger Zoo; 27 March 2012 by John" and I've taken a look at the 54 thumbnails.
I don't understand if it is only a "zooites" sample or the base of more detailed study by the team.
I have some doubts on few pairs which can't be interacting at hundreds of megaparsecs apart, and i suggest to carefully estimate the distance between the two (or three) nuclei of the pair in interaction.
objid_in_pair ra dec z neighbor_in _pair n_ra n_dec n_z sep (arcmin) dist Mpc
588017604696408195 221.32866 38.805889 0.059753 588017604696408114 221.34691 38.781006 0.032244 1.72 203.2
588017604696408195 is NGC 5753 (and the other one is NGC 5755)!
You missed, that in NED there is given a different redshift than in SDSS and an essential note: "SDSS has z = 0.059750 +- 0.000167" !
NED cites z=0.032099. (It has nearly same redshift as the other galaxy and thus they might interact.)
So the redshift or spectrum in SDSS (DR7/DR8) seems to be wrong! (I have no clue, why the redshift in SDSS is different than in NED!)
On the other hand, I wonder, if the disturbance of NGC 5755 is really caused by NGC 5753 or if NGC 5755 is actually itsself a GPair (at the spectrum target in SDSS there seems to be another galaxy: 588017604696408114).
NGC 5753 -- Galaxy in Pair of Galaxies
NGC 5755 -- Interacting Galaxies