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I am trying to get some data from the Sloan digital sky survey (SDSS). This task turned out to be challenging for me as someone with only little knowledge about astronomy and maybe someone here can help me. What I need is data for all galaxies of the SDSS with their optical spectroscopy and position.

I suppose I need:

  • redshifts
  • RA (right ascension)
  • dec (declination)
  • classifications of all SDSS spectra

from the Optical Spectra Catalog Data

I found a script to convert ra/dec/redshift to x/y/z coordinates. Will I need "the associated photometric position based matches" and "stellar parameter (SSPP) results" to get RA and dec? I have no idea what these are.

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This question may be more appropriate to ask the SDSS collaboration itself: – Joshua Jul 11 '14 at 18:07
Also, the coordinates for galaxies are likely to be in Galactic lat/long, which can be converted to x/y/z given redshift. And even I don't know what the two terms you mentioned are (in spite of having a fair knowledge in astronomy), so, as Joshua mentioned, you would probably be better asking SDSS people this stuff. – Takku Jul 11 '14 at 19:49
"the associated photometric position based matches" = this is a plate image of the sky where the spectrum was taken so you can make sure it's the spectrum of the object you want. "stellar parameter (SSPP) results" = SEGUE Stellar Parameter Pipeline which is an analysis pipeline for stars. I would say no for both. – Aaron Jul 13 '14 at 9:37
up vote 2 down vote accepted

Use the Optical Spectra Query Form. You'll want to set PRIMTARGET to "GALAXY". Here's the list of possible parameters it can return Note, there is a query limit of 500,000 rows, so you'll have to break up the query since you'll have more spectra than that.

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