Optical Spectra Overview


Quick Look view of the host galaxy of supernova 2011V (<a href="http://adsabs.harvard.edu/abs/2012A%26A...544A..81H">Hakobyan et al. 2012</a>). Click on the image to go to the Quick Look tool.
Quick Look view of the host galaxy of supernova 2011V (Hakobyan et al. 2012). Click on the image to go to the Quick Look tool.

Data Release 13 includes the complete dataset of optical spectroscopy of the Sloan Digital Sky Survey through July 2015 – more than four million spectra. DR13 includes all data from the Baryon Oscillation Spectroscopic Survey (BOSS) (a total of 1.5 million galaxy spectra at redshifts 0.15 < z < 0.7 and quasar spectra at z > 2.0), and also data collected by the Sloan Extended Quasar, ELG, and LRG Survey (SEQUELS). DR13 also features catalogs of galaxy parameters estimated in various ways.

DR13 also includes all spectra and derived stellar parameters measured by the Sloan Extension for Galactic Understanding and Exploration (SEGUE) , as well as all the spectra of the original Sloan Digital Sky Survey.

The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is observing luminous red galaxies (LRG), quasars and emission line galaxies (ELG) at redshifts 0.7 < z < 2.0, to fill the redshift gap of BOSS. These spectra will be made publicly available in future data releases.


The quickest way to view SDSS spectroscopic data is the SkyServer Quick Look tool. Quick Look shows an image and spectrum for all sky objects for which the SDSS has measured a “science primary” spectrum. The tool also shows the object’s spectroscopic classification (star/galaxy/quasar) and redshift, and gives links to further data, including the spectrum as a FITS file.

All spectroscopic catalog data is available through the search tools of SkyServer. The Spectroscopic Query Form lets you search for spectroscopic catalog objects by position, spectral classification, redshift, and other constraints in spectroscopy and imaging. SQL Search lets you create your own search; see the SkyServer SQL Tutorial to learn how to write SQL queries.


An even more flexible and powerful interface is CasJobs, which allows you to save and analyze all your search results.

Science Archive Server

Summary FITS files containing the best-fit redshifts and parameters for all optical spectroscopic objects, as well as all raw and processed SDSS/SEGUE/BOSS/SEQUELS/eBOSS data are available from the Science Archive Server (SAS), including all directories and files listed in the Data Model.
The Science Archive Webapp provides a searchable interface for optical spectra, and includes an interactive spectrum viewer, and a data download facility (supports both rsync and wget):

More information about SDSS spectra

These pages describe how to use SDSS spectroscopic data. Use the links below (echoed on the left sidebar menu on each page) to learn more.

Understanding SDSS spectra:
describes how SDSS spectroscopic data are organized, and the various spectroscopic observing programs that compose the full SDSS.
describes the steps in
the spectroscopic data processing, and the files created at each step.
Available data:
describes in detail what spectroscopic data products are available through the Science Archive Server and SkyServer.
Target flags:
describes how to track the way in which a spectrum was chosen (targeted) for spectroscopic follow-up.
Spectroscopic catalogs:
describes the parameters available in SDSS spectroscopic catalogs, such as redshifts and classifications.
describes additional galaxy parameters calculated from SDSS spectra.
Stars (SSPP):
describes the SEGUE Stellar Parameter Pipeline, which estimates stellar atmospheric parameters, and how to use SSPP data.
SEGUE SQL cookbook:
describes getting stellar parameters out of the SQL database, with examples.
describes some important caveats in using SDSS spectroscopic data, including how to check data quality.

To learn how the SDSS chose objects for spectroscopic observation, see the SDSS Target Selection pages.