Need datas

• by Zebx

  If the z from photoz of the galaxy at 03:00 was better perhaps one could say they're merging 😦 z for central galaxy(a) is 0.09188(1.2 bly) from spectrum. Z for galaxy(b) at 03:00 from photoz is between 0.0725(957mly) and 0.1040(1.34bly). Maybe b is farther though.

  Posted July 20, 2016 1:30 AM

• by Budgieye moderator

  Yep! Photoz are not accurate. They usually have a huge error, and sometimes can be very wrong. It is only measuring the ratio of colours in the galaxy, and they eyeball that sees in 3 colours can do as well. My eye says that they are about the same distance, but not interacting. In SDSS click on All Spectra, just in case there is one. Occasionally, you can go into NED and click on spectra, and there will be one there.

  Target galaxy

  

  http://skyservice.pha.jhu.edu/DR9/ImgCutout/getjpeg.aspx?ra=227.65070542&dec=2.01654136&scale=0.2&width=200&height=200&opt=G#

  The z is accurate, because of the absorption lines can be measured exactly.

  Galaxy at 3 oclock.

  

  http://skyservice.pha.jhu.edu/DR9/ImgCutout/getjpeg.aspx?ra=227.64535324&dec=2.01566857&scale=0.2&width=200&height=200&opt=G

  z 0.088252
  zErr 0.015766

  which as you say, has a big error.

  Posted July 20, 2016 1:30 PM