Viewing densities of galaxy positions

[selden]

Here's my most recent attempt to reproduce the SDSS image Orange Pie, using Celestia to view the results. (I did something similar a long time ago using DR2.) The range in Z values is somewhat larger than the SDSS image, although the outermost whole green circle corresponds to the outer limit of theirs. Coloration is strictly by density, going from red for the least dense through yellow to white at the most dense.

I used http://skyserver.sdss.org/Casjobs to select galaxies in the appropriate RA and Dec ranges from the most recent SDSS data release, DR13, although I think they've only improved the processing of the data provided in DR7, not added anything new. The lower fan in the picture is "Stripe 82", the one which is used by the "Galaxy Zoo" project.

A Celestia "Addon" can be made available in a few days which includes this and some additional "fans" if anyone is interested.

Here's a picture showing the entire dataset for the same regions.

[john71]

Yes, yes, this is fantastic! Please share the add-on!

[selden]

sdss_dr13_galaxies.zip (v0.9; 30MB expands to 37MB, 06Jun17)
is now available. This Addon includes a menu which allows you to view up to 2,204,870 galaxy positions. These positions were taken from the SDSS DR13 data release.

Also, see https://www.classe.cornell.edu/~seb/celestia/catalogs.html#3.5.12

[john71]

Thanks for sharing it! Excellent!

Added after 57 minutes 29 seconds:
Just one question: isn't it a little bit too big? I mean some galaxies are farther than 30000 Mpc...