In addition to the primary SDSS photometry and spectroscopy, there are a few extra catalogs created by our collaborators that are distributed through the SAS. These Value-Added Catalogs (VACs) are listed below, and include catalogs that were released in earlier data releases.
Sodium ISM Absorption in MWM BOSS
Measurements of Na I D absorption from the interstellar medium obtained from MWM BOSS stellar spectra
Catalog Data
Abstract
This value-added catalog provides measurements of Na I D interstellar absorption for stars in DR20, derived using the model described in McQuaid et al. (2026). This includes nearly the entire catalog of stellar spectra observed for Milky Way Mapper DR20 using the BOSS spectrographs, comprising roughly 1.3 million sources. The model fits each spectrum with MaStar stellar templates that have been cleaned of their intrinsic Na I D contribution (Rubin et al. 2025), isolating the interstellar absorption component along each sight line. Extinction estimates derived from the continuum fit are also provided for each source, offering an independent check on the dust properties along the line of sight. This VAC is formatted as a FITS file with two HDUs: the primary HDU contains metadata and header information, while the second HDU contains a FITS table with the Na I D absorption measurements and extinction values for each of the sources. Further information about this VAC can be found in McQuaid et al. (2026).
Catalog last modified: 2026-07-30 12:12:10