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For a data visualization project, I want to extract galaxy data (in x y z coordinates) from galaxy catalogue of within 150 mpc and project each of those galaxies as dots and visualize them in a 2D projection of a spherical volume. Need your help in getting this data set and how to achieve it?

Would be grateful for any help in any way!

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    $\begingroup$ The NED database ned.ipac.caltech.edu $\endgroup$
    – ProfRob
    Dec 27, 2016 at 14:37
  • $\begingroup$ usno.navy.mil/USNO/astrometry/optical-IR-prod/nomad contains one billion objects, but you probably won't need something that extreme. $\endgroup$
    – user21
    Dec 27, 2016 at 16:47
  • $\begingroup$ Every catalog of galaxies is going to be missing all those galaxies that lie behind the milkyway. There will be a big slice missing, whatever data you use. $\endgroup$
    – James K
    Dec 27, 2016 at 17:01
  • $\begingroup$ @barrycarter As I'm sure I've mentioned before (?), Nomad is mostly a stellar catalogue. $\endgroup$
    – ProfRob
    Dec 27, 2016 at 17:48
  • $\begingroup$ @RobJeffries You are correct. heasarc.gsfc.nasa.gov/docs/cgro/db-perl/W3Browse/… may be more helpful. $\endgroup$
    – user21
    Dec 28, 2016 at 5:56

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You could try the Hyperleda database. You will have to learn to use the database, which possibly means learning a little bit of SQL. For starters you could select all items with redshift $cz < H_0\times 150$ km/s, using redshift as a distance indicator. This should be roughly ok at 150 Mpc (though I don't see any viable alternative).

The returned catalogue should have (at least) RA, Dec, redshift, possibly a size and morphology and, for a small subset of the galaxies, a redshift-independent distance estimate. Given that very nearby galaxies (in the local group or a $d < 50 $Mpc) are not fully part of the "Hubble flow" you might choose to use these in preference to a redshift-distance where available.

X,Y,Z coordinates (based in the equatorial system) can be calculated using this prescription or in Galactic coordinates (with respect to the centre and orientation of our Galaxy can then be found using the operations defined in Johnson & Soderblom (1987).

I have no idea how complete this database will be. Certainly there will be an issue with extinction near the Galactic plane.

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  • $\begingroup$ For nearby galaxies, do you mean that redshift-independent distance is preferable to redshift? $\endgroup$
    – Mike G
    Mar 28, 2017 at 16:48
  • $\begingroup$ @MikeG Yes I do. Edited. $\endgroup$
    – ProfRob
    Mar 28, 2017 at 17:36

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