NuSTAR CALDB Release Version: 20200429 NuSTAR CALDB Release Version: 20200428 Release 20200429 includes new releases of the CLOCKFILE and updates to the ON-AXIS ARFs: CLOCKFILE: ========== This is a major upgrade of the NuSTAR clock correction file. Details and comparisons to the previous clock correction file can be found here: http://www.srl.caltech.edu/NuSTAR_Public/NuSTAROperationSite/clockfile.php The clock correction file keeps the NuSTAR relative time (after barycentric corrections) accurate to better than 100 micros and accounts for drifts in the NuSTAR clock caused by temperature variations. This clockfile is compatible with the current version of barycorr. See the above link or the barycorr fhelp file for its usage. ON-AXIS ARF UPDATE =================== A rip in the multi layer insulation (MLI) at the exit aperture of OMA, the optic aligned with detector focal plane module FPMA, has resulted in an increased photon flux through OMA that has manifested itself as a low energy excess. The effect is largest for 3 keV, with an exponential decrease which vanished between 5-8 keV. The rip occurred in early 2016 and progressively enlarged through 2017 to stabilize again in 2018. To compensate for the increased flux, we have changed the amount of MLI covering the opening, F_MLI (in fraction of opening), in the on-axis ARF of module A. To accommodate the time dependent component we are releasing three new ARFs valid in different ranges: DAT FILE MLI FRACTION ------------------------------- ------------------- ------------ Launch < date < 01/01/2017 nuA20100101v007.arf F_MLI=0.96 01/01/2017 <= date < 01/01/2018 nuA20170101v007.arf F_MLI=0.91 01/01/2018 <= date nuA20180101v007.arf F_MLI=0.86 The changes in the on-axis ARF affects all FPMA data from launch. No changes have been made to FPMB. The impact on data before 2017 is small and the correction removes a 1% excess in FPMA between 3-4 keV. The correction for data after 2018 removes a 4% excess at 3keV that has vanished at 6 keV. Details on the issue, and a note on future releases, can be found at https://arxiv.org/abs/2005.00569.