# What’s New in DR17

Data Release 17 (DR17) is the final data release of the Sloan Digital Sky Survey IV.

DR17 contains new optical and infrared spectra from both Apache Point Observatory and Las Campanas Observatory. Previously released integral-field datacubes and maps, stellar library spectra, as well as images, are also included in DR17.

(extended) Baryon Oscillation Spectroscopic Survey (eBOSS)

The SDSS's component extended Baryon Oscillation Spectroscopic Survey has started its mission in 2014 to map the Universe with the baryon acoustic oscillation (BAO) feature in the large-scale structure of the Universe, using data from both galaxy clustering and the Lyman-α forest.

eBOSS coverage area included in DR16 (click to enlarge)

Data Release 16 is the final public data release for eBOSS, and includes optical spectra of Luminous Red Galaxies (LRGs) and quasars (QSOs). The data release also includes optical spectra from a transitional project between BOSS and eBOSS called the Sloan Extended Quasar, ELG, and LRG Survey (SEQUELS), designed to test target selection algorithms for eBOSS. These SEQUELS spectra, as well as previously released BOSS spectra, had been re-reduced using the reduction pipeline updated for DR16.

DR16 also contains optical spectra of the eBOSS subprograms SPectroscopic IDentfication of ERosita Sources (SPIDERS) survey and Time-Domain Spectroscopic Survey (TDSS), as well as various Value Added Catalogs, which include, among others, targeting information.

eBOSS spectra are available through both the Science Archive Server (SAS) and the Catalog Archive Server (CAS) and can also be inspected and downloaded with our Science Archive Webapp (SAW). For more information on the eBOSS data in DR16, see:

Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2)

APOGEE-2 is a large-scale survey of Milky Way stellar chemistry and kinematics. High-resolution infrared (H-band) spectroscopy allows APOGEE-2 to peer through interstellar dust extinction to provide a large, uniform database of precision stellar measurements throughout the Galaxy, spanning from the central bulge, through the disk and into the halo. APOGEE-2 operates in both the Northern and Southern hemispheres using near-twin spectrographs.

A map of the individual fields targeted by APOGEE-1 and APOGEE-2 and having observations included in DR17 (click to enlarge). The fields are color-coded by the number of targets in DR17.

In DR17, APOGEE-2 releases an additional 2 years of observations from both Apache Point and Las Campanas Observatories. All observations taken with the APOGEE-N and APOGEE-S spectrographs in APOGEE-1 and APOGEE-2 have also been homogeneously processed with the most updated version of the pipelines. APOGEE-2 releases spectra, radial velocities, stellar parameters (e.g., $T_{\rm eff}$ and log $g$), and more than 20 elemental abundances.

The DR17 pipelines have seen significant upgrades. In particular, the radial velocity and spectral combination pipeline has been completely reworked to provide more reliable measurements for the faintest targets. ASCPAP was also completely rewritten. The primary spectral library uses the SynSpec spectral synthesis code and uses an NLTE treatment for Na, Mg, K, and Ca. Additional supplementary analyses were produced using other spectral libraries.

In DR17, a total of XX Value-Added Catalogs have been produced by the APOGEE-2 team that dramatically expand upon and enhance the primary data processing. These products including binary star classifications, distances, orbital properties, cluster membership, photometric properties, and more.

APOGEE-2 infrared spectra are available through both the Science Archive Server (SAS) and the Catalog Archive Server (CAS), and can also be inspected and downloaded with our Science Archive Webapp (SAW). For more information on the APOGEE-2 data in DR17, see:

Mapping Nearby Galaxies at APO (MaNGA)

The MaNGA survey area (click for a larger view). Blue indicates observed fields (plates). See MaNGA footprint page for more details.

MaNGA is an integral-field spectroscopic survey that has mapped more than 10,000 galaxies in the nearby Universe. DR17 is MaNGA's final public data release, and contains datacubes and row-stacked spectra (RSS) for 11,273 MaNGA observations (including ancillary targets), along with derived data products and maps produced by the MaNGA Data Analysis Pipeline and various Value Added Catalogs.

MaNGA observes galaxies with fiber bundles that vary in size from 19 to 127 fibers (12 to 32 arcsec diameter on sky); larger bundles target larger galaxies, resulting in a uniform radial coverage. As a result, the number of spectra within each data cube and RSS file will vary depending on the fiber bundle size.

The MaNGA data cubes, row-stacked spectra and maps are available through both the SAS and the CAS, and can be visualised and analysed with Marvin. For more information on the MaNGA data, data products and tools, see:

MaNGA Stellar Library (MaStar)

MaStar color-luminosity diagram for DR16 (click to enlarge)

MaStar is MaNGA's stellar library program: it observes stars with MaNGA's integral-field bundles in bright time. DR15 was MaStar's first data release, and contains 8,646 good quality spectra for 3,326 unique stars.

The MaStar spectra are available through both the SAS and the CAS, and can also be inspected and downloaded with our Science Archive Webapp (SAW). For more information on the MaStar data, see: