The DESCQA framework provides rigorous validation protocols for assessing the quality of high-quality simulated sky catalogs in a straightforward and comprehensive way. DESCQA enables the inspection, validation, and comparison of an inhomogeneous set of synthetic catalogs via the provision of a common interface within an automated framework. An interactive web interface is also available at https://portal.nersc.gov/projecta/lsst/descqa/v2/.

desitarget selects targets for spectroscopic follow-up by Dark Energy Spectroscopic Instrument (DESI). The pipeline uses bitmasks to record that a specific source has been selected by a particular targeting algorithm, setting bit-values in output data files in a number of different columns that indicate whether a particular target meets specific selection criteria. desitarget also outputs a unique TARGETID that allows each target to be tracked throughout the DESI survey. This TARGETID encodes information about each DESI target, such as the catalog the target was selected from, whether a target is a sky location or part of a random catalog, and whether a target is part of a secondary program.

legacypipe produces DESI Legacy Imaging Surveys (aka the Legacy Surveys). It can process individual exposures from many cameras, including the Dark Energy Camera on the Blanco telescope, the 90Prime camera on the Bok telescope, and the Mosaic3 camera on the Mayall telescope. The code can also process exposures from the Hyper-SuprimeCam on Subaru, the old SuprimeCam on Subaru, MegaCam on the Canada-France-Hawaii Telescope, and image products from the GALEX and WISE satellites. Legacypipe performs source detection, and then measurement via forward-modeling using The Tractor (ascl:1604.008). It generates coadded output images as well as catalogs, plus a variety of metrics useful for understanding the properties of the imaging.