Getting all spectra and corresponding imaging data

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For your convenience, we publish a variant of the DR2 spectroscopic data set which has all spectra and corresponding object lists entries and atlas images. It consists of the following set of file for each plate of 640 fibers:

• spDiag-$mjd-$plate.par: the spectro1d summary
• spSpec-$mjd-$plate-$fiber.fit: the catalog of spectral lines per spectrum
• spPlate-$plate-$mjd.fits: the image of reduced spectra (1 spectrum per row)
• plPlugMapM-$plate-$mjd-$mapping.par: the mapping of targets to fibers
• spObj-$plate-$mjd-$rerun.fit: joined tsObj and spDiag and plPlugMap data for all fibers, hdu 1 = best, hdu 2 = target (these are called tsObjFromMap on the DAS download form)
• spAtlas-$plate-$mjd-$fiber.fit: best and target atlas images for all 5 colors for all fibers

The data model for a spObj-*.fit file is nearly the same as that for a tsObj file, except that a tsObj file contains all imaging information for all objects (bright and faint) in a particular 0.033 sq. deg. imaging field, while a spObj file contains all imaging information for all fibers on a particular spectroscopic plate, with an area of 7 sq. deg. spanning many imaging fields.

You can access these files, as well as catalogs of just the redshifts, in bulk at the following locations:

The full set of plates

• one subdirectory per plate: http://das.sdss.org/DR2/data/spectro/ss_23
  An example of what is in these directories: plate 666
• one tar.gz file of ~85MB per plate: http://das.sdss.org/DR2/data/spectro/ss_tar_23
  We recommend to use these. Most easily retrieved using wget or rsync, with the following command:

  rsync -vtrLPR rsync://dr2@rsync.sdss.org/DR2/spectro/ss_tar_23/ ./

  The password is dr2. Also see our rsync help page.

Just the redshifts

Galaxies

• All objects classified as galaxies: gals-dr2.fit.gz, 524M
• Object from the tiled samples
  • Main galaxy sample: main_gals-dr2.fit.gz, 438M
  • Luminous Red Galaxies (LRGs): main_lrgs-dr2.fit.gz, 49.3M

Quasars

• All objects classified as quasars: qsos-dr2.fit.gz, 69.3M
• Objects targeted as main survey quasars: main_qsos-dr2.fit.gz, 23M

Note that there is a vetted DR1 quasar catalog presented by Schneider et al. 2003. The information contained in that catalog supersedes the information contained in all other data sources. We strongly recommend cross-checking the list given here against the Schneider et al. catalog. Future data releases will incorporate the information from the vetted quasar catalogs.

Stars

Objects classified as stars stars-dr2.fit.gz, 44M

Unknown and sky fibers

Objects whose type could not be identified, and sky fibers used to perform sky subtraction from the spectra. unks-dr2.fit.gz, 27.6M

What about objects not observed due to fiber collisions?

You will want the tiling information.