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.

FitCov estimates the covariance of two-point correlation functions in a way that requires fewer mocks than the standard mock-based covariance. Rather than using an analytically fixed correction to some terms that enter the jackknife covariance matrix, the code fits the correction to a mock-based covariance obtained from a small number of mocks. The fitted jackknife covariance remains unbiased, an improvement over other methods, performs well both in terms of precision (unbiased constraints) and accuracy (similar uncertainties), and requires significant less computational power. In addition, FitCov can be easily implemented on top of the standard jackknife covariance computation.

"legacypipe" is the code used to produce the DESI Legacy Imaging Surveys (aka the Legacy Surveys). It can processes individual exposures from many cameras, including the Dark Energy Camera on the Blanco telescope, the 90Prime camera on the Bok telescope, the Mosaic3 camera on the Mayall telescope (these three were used for the Legacy Surveys); as well as 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 code. It generates coadded output images as well as catalogs, plus a variety of metrics useful for understanding the properties of the imaging.