[vsnet-grb-info 21857] Improved Fermi/GBM GRB localizations
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Tue Mar 12 19:03:36 JST 2019
TITLE: GCN CIRCULAR
NUMBER: 23956
SUBJECT: Improved Fermi/GBM GRB localizations
DATE: 19/03/12 10:02:27 GMT
FROM: Jochen Greiner at MPI <jcg at mpe.mpg.de>
Improved Fermi/GBM GRB localizations
J. Greiner, B. Biltzinger, F. Kunzweiler, F. Berlato, J.M. Burgess
(all MPE Garching) report:
Effective immediately, we will begin issuing GCN circulars for
bright gamma-ray bursts triggered onboard the Gamma-Ray Burst Monitor
(GBM) on Fermi. These GCNs will include localizations generated with
the BALROG scheme (Burgess et al. 2018, MNRAS 476, 1427). BALROG fits
the count data of the GBM detectors for spectrum and location on the
sky simultaneously. This procedure allows us to get rid of the
"3.7 deg core plus 10 deg tail" systematic error (Connaughton et al. 2015,
ApJS 216, 32). Our BALROG positions have a remaining systematic error
of 2 deg when arriving from directions coincident with the spacecrafts
solar panels, and 1 deg otherwise (Berlato et al. 2019, ApJ, in press;
arXiv:1902.01082).
We plan to send GBM localizations for the about 20% brightest GBM triggers
(with 2 sigma error radii < 10 deg), plus otherwise interesting GRBs.
Information on the localizations for all GRBs, including fainter ones,
will be logged at https://grb.mpe.mpg.de/ . The latency of these
localization fits will be about 30 min. after the onboard trigger.
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