NuSTAR CALDB Release Version: 20220510

Release Type: CALDB release

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Contents:

data/nustar/fpm/index/caldb.indx20220510
data/nustar/fpm/bcf/gain/nuAgain20100101v010.fits
data/nustar/fpm/bcf/clock/nuCclock20100101v139.fits


Summary of changes:

This is an incremental update to the NuSTAR CALDB which includes the latest NuSTAR
clock file and an update to the gain for FPMA DET2 which corrects a longterm drift in
the gain for this particular detector since 2015.


CLOCK: v139

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This is an update 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 microseconds 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.
 
Due to the nature of the clockfile correction, we note that the timing solution may improve for the ~14 days prior to the generation of the clockfile as more data are incorporated into the fit. For high precision timing of very recent observations we recommend either waiting for the next clock file update or contacting the NuSTAR SOC for assistance.

There was an issue with the NuSTAR ground station clock between 2021/07/30 and 2021/08/04. As of this release, the clockfile performance appears to be nominal during this period. But please see the NuSTAR SOC Clockfile page for a list of potentially affected sequence IDs and targets and, if there are any anomalous timing signatures for these observations, please contact the NuSTAR SOC for guidance.


GAIN: FPMA v010

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Adjusts the long-term gain calibration for FPMA DET2. This release is only for FPMA and only affects the gain calibration for that detector. This changes corrects a total 2% drop in the line energy calibration from 2015 to 2022 on this detector.

Details of the analysis can be found in the calibration memo (CAL_NuSTAR_20220510.pdf) available on the NuSTAR calibration webpage at the HEASARC:

https://heasarc.gsfc.nasa.gov/docs/heasarc/caldb/nustar/docs/fpm/index.html