  The memo describes the methods used to track the long-term gain variations in
the NuSTAR detectors. It builds on the analysis presented in Madsen et al.
(2015) using the deployable calibration source to measure the gain drift in the
NuSTAR CdZnTe detectors. This is intended to be a live document that is
periodically updated as new entries are required in the NuSTAR gain CALDB
files. This document covers analysis up through early-2022 and the gain v011
CALDB file released in version 20240226.
