Chandra, Meet Sloan: SDSS Spectroscopy of Chandra Source Catalog Counterparts

The Chandra Source Catalog version 2.1 (CSC2.1) will be released early in 2023, and will encompass close to four hundred thousand well-characterized X-ray sources observed by Chandra from launch (1999) through 2021, covering about 800 square degrees. The Sloan Digital Sky Survey V (SDSS-V) will be obtaining new optical and infrared spectroscopy of Chandra source counterparts in fields across the entire sky. SDSS-V is expected to provide new spectra, pipeline classifications and velocities for tens of thousands of CSC source counterparts. These will add to the seventeen thousand such counterparts that have spectra already in the SDSS archive. SDSS-V will newly provide infrared spectra for a fraction of CSC2.1 sources, mostly in the Galactic plane, that have bright infrared but no optical counterparts.