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When is this page updated?
This page is updated when data are delivered to the HEASARC, or within about two weeks after the data are taken. If you are interested in quicklook data, please contact the SOC.

How to use the SAA reports:
Each PDF report (linked to the SequenceID in the table below) contains multiple pages that show the effect of the various SAA filter options. The nupipeline / nucalcsaa filter options are given at the top of each lightcurve on the left panels, while the count rate as a function of orbital position is given in the right panels. The count rates in both the lightcurve and the orbital track plots are integrated over the entire field of view and so include both source and background counts.

How to use the background reports:
Each report contains time histograms and geographic maps showing the total background, the low energy background (usually associated with stray light and/or solar flares), and the high-energy particle background (associated with radiation belts). If "spikes" are seen in these plots that are not removed by the SAA filtering then the user may need to do more manual filtering of the data.

For sources that are bright (approx. >1 counts per second), the effect of the SAA filtering will likely be negligible. For fainter sources it is up to the user to determine whether or not to use the SAA filtering (the default pipeline option is NOT to use any filtering). The user should balance the reduction in the apparent noise vs the amount of exposure that remains (noted as a percentage of the unfiltered exposure time in the top right above each orbital plot).

Key features:
The enhancement of NuSTAR background event rates from passage through the SAA is usually seen between ~300 and ~330 degrees longitude and <1.5 degrees latitude while the "tentacle" region is around ~270 degrees longitude and above about -2 degrees latitude. The strength and size of the SAA and the strength of the background in the tentacle region both depend on the space weather conditions. It is possible that even for faint sources that no filtering may be required; the background event rate around the tentacle region is highly dependent on the space weather conditions at the time of the observation and so filtering may only occasionally be beneficial.

Previous Version:
This page was updated to include new versions of the SAA reports and the links to the background reports in October 2023. The previous version of this page and all of its associated reports can be found here.

For more information see the NuSTAR background filtering webpage.