Data Release 20 of the Milky Way Mapper survey provides new BOSS optical spectra for approximately 1.2 million stars across both the Northern and Southern Hemispheres. In addition, it includes the APOGEE near-infrared spectra for approximately 390,000 stars previously released in DR19 and carried over unchanged into DR20. For more information on accessing these data products, please see this page.
In addition, as a collaboration that cares deeply about the scientific legacy it leaves behind, we invest considerable effort in validating the data products we release. While we strive to identify and correct issues whenever possible, some limitations and features of the data — or of the stellar parameters inferred from them — cannot be eliminated and are instead documented as caveats. We therefore strongly encourage users to consult both the Milky Way Mapper Caveats and the general SDSS Caveats pages before using the data products and derived stellar parameters.
In this section we offer our current thinking about the strengths and weaknesses of various aspects of our data. These are meant as guides to help share insights and informal information.
We offer 7 guides:
- Stellar Parameters
- Stellar Abundances
- Radial Velocities
- Line Indices
- Spectra
- MWM Targeting
- From DR17 to DR19 for the ASPCAP stellar parameters and abundances (not updated from DR19, but still relevant because the ASPCAP files in DR20 are copied from DR19.)