NuSTAR CALDB Release Version: 20200912 Release Type: CALDB release CLOCKFILE: ========== Contents: fpm/bcf/clock/nuCclock20100101v110.fits Summary of changes: Clock files v.109 and later contain an improvement of the clock offset model that builds on the fine clock correction introduced in v.095. For clock files prior to v.100, the absolute alignment to UTC time has been measured to be systematically off by ~5ms Additionally, the model used to produce the clock file suffered from time intervals with no temperature measurements (such as reboots of the system). More details about the impact of the clock correction file are available at the NuSTAR SOC at this link: http://www.srl.caltech.edu/NuSTAR_Public/NuSTAROperationSite/clockfile.php