NuSTAR CALDB Release Version: 20240229
 
Release Type: CALDB release
 
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Contents:
 
data/nustar/fpm/index/caldb.indx20240229
data/nustar/fpm/caldb.indx
data/nustar/fpm/bcf/gain/nuAgain20100101v011.fits
data/nustar/fpm/bcf/arf/nuAtemp0_20221201v001.arf
data/nustar/fpm/bcf/clock/nuCclock20100101v177.fits.gz

Summary of changes:
 
GAIN: FPMA v011
 
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Adjusts the long-term gain calibration for FPMA DET0. This release is only for FPMA and only affects the gain calibration for that detector. This change corrects a small 0.2% drop in the line energy calibration from 2020 to 2022 on FPMA DET0.
 
Details of the analysis can be found in the calibration memo:
 
https://heasarc.gsfc.nasa.gov/docs/heasarc/caldb/nustar/docs/fpm/index.html
 
…while the most up-to-date version of this analysis is found on the arXiv here:
 
https://arxiv.org/abs/2206.04058
 
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ARF: Removing the FPMA Effective Area Temperature Dependence
 
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This patch prevents the incorrect use of the temperature-dependent ARF correction introduced in the NuSTAR CALDB 20200813 and NuSTARDAS v2.0.0. After December 2022, the thermistor used to select the temperature-dependent MLI correction is no longer operating correctly. This can result in an incorrect effective area produced by nuproducts if the mlicorr=yes keyword is set. The impact is a small (few %) apparent “tail” in NuSTAR spectra when comparing results from FPMA and FPMB.
 
The updated CALDB removes the ability to perform a temperature-dependence correction so that mlicorr=yes and mlicorr=no should result in identical output ARF files.
 
No adjustments to the NuSTARDAS are required by this CALDB update.




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CLOCKFILE:
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This release includes a new release of the CLOCKFILE, v177

released at the HEASARC: 2024-02-29
 
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.