Available Optical Spectral Data

The major spectroscopic results are contained in a few different file structures (on SAS) and database tables (in CAS), listed below. In the case of the SAS files, the large FITS files are all line-by-line matched, so that the Nth entry in any file refers to the same object. The “plates” file, listed first below, is especially useful as a full list of the plates released. Note that the links into SAS below bring you into the full directory tree; it is best not to wander there before first reading both Understanding SDSS Spectroscopic Data and the data model.

Methods for accessing these data are summarized on the data access page. Also see the spectro pipeline page for a more complete list of spectro pipeline output files and their download locations.

Spectral FITS files are also available through the SkyServer Explore tool.

Catalogs of quantities measured from Spectra
SAS location CAS table Description
plates-dr17.fits(3.7 Mb)
(in SPECTRO_REDUX; see datamodel)
plateX List of all DR17 plates
(available as Yanny file too)
specObj-dr17.fits (6.7 Gb)
(in SPECTRO_REDUX;(see datamodel)
(only primaries)
Redshifts and classifications of all SDSS spectra
(also available in BOSS-only and SDSS-only versions)
ssppOut-dr12.fits (1.8 Gb)
(in SSPP_REDUX; see datamodel)
sppParams Stellar parameters from SSPP
ssppOut-dr12.lineindex.fits (2.3 Gb)
(in SSPP_REDUX; see datamodel)
sppLines Stellar line indices from SSPP
photoPlate-dr17.fits (17.5 Gb)
(in SPECTRO_REDUX; see datamodel)
join on photoObj Photometric flux-based matches
photoPosPlate-dr17.fits (17.5 Gb)
(in SPECTRO_REDUX; see datamodel)
join on photoObj Photometric position-based matches
photoMatchPlate-dr17.fits (840 Mb)
(in SPECTRO_REDUX; see datamodel)
details of match results
galSpecInfo-dr8.fits (364 Mb)
(in SPECTRO_REDUX; see datamodel)
galSpecInfo Information for each galaxy processed by Garching group (deprecated in DR10)
galSpecIndx-dr8.fits (1.9 Gb)
(in SPECTRO_REDUX; see datamodel)
galSpecIndx Index measurements for each galaxy (deprecated in DR10)
galSpecLine-dr8.fits (1.7 Gb)
(in SPECTRO_REDUX; see datamodel)
galSpecLine Line measurements for each galaxy (deprecated in DR10)
galSpecExtra-dr8.fits (339 Mb)
(in SPECTRO_REDUX; see datamodel)
galSpecExtra Extra physical parameters for each galaxy (deprecated in DR10)
Spectral Data
SAS location CAS table Description
see datamodel)
Coadded spectra grouped by plate
see datamodel)
Individual spectra, one file per PLATE-MJD-FIBER
specObjAll PNG images of each spectrum