SDSS has taken millions of spectra over its lifetime, using its legacy plug plate system. All these spectra and their derived data products are publicly available in the SDSS data releases. Follow the links below to the SDSS-IV website for information on where to find these spectra, how to work with them, and relevant tutorials.
There have been several optical spectroscopic programs during the lifetime of SDSS, using the original spectrographs, the BOSS spectrographs and the MARVELS spectrograph. An overview of all these programs is given on the SDSS-IV optical spectroscopy webpage, which also provides information on data access, tutorials, and documentation.
A list of the surveys with links to their descriptions is given below, split into extragalactic and Milky Way observing programs.
A brief summary of these extragalactic observing programs is given on the SDSS-IV Extragalactic Observing Programs page.
For the Integral Field Unit (IFU) spectra observed by the Mapping Nearby Galaxies at APO (MaNGA) survey, see the SDSS-IV MaNGA Overview page.
For the infrared-wavelength Milky Way & Local Group spectra observed by the Apache Point Observatory Galaxy Evolution Experiment (APOGEE), see the SDSS-IV APOGEE Overview page.
For the MaNGA Stellar Library (MaStar), see the SDSS-IV MaStar Overview page.
APOGEE (APO Galactic Evolution Experiment) was an infrared, high-resolution spectroscopic survey in SDSS-III to study the stellar components of the Milky Way, including its bulge/bar, disk, and halo. The survey continued in SDSS-IV as APOGEE-2, expanding to the Southern Hemisphere with increased coverage of the Milky Way and also the Magellanic Clouds. The APOGEE data provide a wide view of the radial velocities, fundamental parameters, and elemental abundances of stars throughout the Milky Way and Local Group. A primer on spectroscopy, especially in the near-infrared, as well some background on the Milky Way Galaxy, can be found here.
The APOGEE spectra, pipelines, and data products are described on the SDSS-IV infrared spectroscopy webpages, which also include data tutorials and descriptions of the ancillary programs. APOGEE spectra can also be displayed interactively in the SDSS webapp.
MaNGA (Mapping Nearby Galaxies at APO) observed 10,000 nearby galaxies with integral-field spectroscopy in SDSS-IV, to map the properties and kinematics of their stars and gas. The spectra and data products are described in detail on the SDSS-IV MaNGA webpages. These pages contain information to access the spectra and data products, details of the sample selection, descriptions of the data reduction and analysis, and tutorials. MaNGA spectra and data products can also be visualised and analysed with Marvin.
The SDSS-IV MaNGA Stellar Library (MaStar) is a stellar spectral library with a wide coverage of stellar parameters, high quality calibration, and identical observing setup as the MaNGA survey. The MaStar spectra and catalogs are described on the SDSS-IV MaStar webpages, which include tutorials. The spectra can also be displayed interactively in the SDSS webapp.