[vsnet-grb-info 20010] Fermi GBM detections of Swift J0243.6+6124 and modification of the GBM trigger configuration

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22097
SUBJECT: Fermi GBM detections of Swift J0243.6+6124 and modification of the GBM trigger configuration
DATE:    17/11/04 01:26:40 GMT
FROM:    Michael S. Briggs at UAH and MSFC  <michael.briggs at 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.