GCN Circular 22097
Subject
Fermi GBM detections of Swift J0243.6+6124 and modification of the GBM trigger configuration
Date
2017-11-04T01:26:40Z (7 years ago)
From
Michael S. Briggs at UAH and MSFC <michael.briggs@nasa.gov>
M. S. Briggs (UAH), C. Wilson-Hodge (MSFC), M. Gibby (Jacobs)
and N. Bhat (UAH) report:
Fermi GBM began triggering on pulses from the Be X-ray binary Swift
J0243.6+6124 (Cenko et al., GCN #21960) on Oct 30th (Bissaldi et al.,
GCN #22075).�� As the source brightened
(https://gammaray.nsstc.nasa.gov/gbm/science/pulsars/lightcurves/swiftj0243.html
and
https://swift.gsfc.nasa.gov/results/transients/weak/SwiftJ0243.6p6124/),
the trigger rate increased until there were approximately 40 triggers
on Nov 3rd.�� To reduce the trigger rate due to this source, the GBM
team has disabled some of the onboard trigger algorithms. We expect
that there will still be a few triggers per day, which might increase
if Swift J0243.6+6124 brightens further.�� The GBM team may make
further modifications to the onboard trigger configuration and will
not issue GCN Circulars to classify individual events from Swift
J0243.6+6124 that were misclassified in automatic notices.
The ground-based GBM subthreshold transient search
(https://gcn.gsfc.nasa.gov/admin/fermi_gbm_subthreshold_announce.txt)
has not been modified and will continue to generate GCN Notices due to
Swift J0243.6+6124 (Briggs et al., GCN #22047).�� There have been more
than 1000 detections of this source by the GBM subthreshold search.