[vsnet-grb-info 17194] GRB 151030A: Fermi GBM observation

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  18545
SUBJECT: GRB 151030A: Fermi GBM observation
DATE:    15/10/31 20:35:30 GMT
FROM:    Peter Veres at UAH  <veresp at gmail.com>

Peter Veres (UAH) reports on behalf of the Fermi GBM Team:

"At 23:58:22.6 UT on 30 October 2015, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 151030A (trigger 467942306 / 151030999).

The on-ground calculated location, using the GBM trigger
data, is RA = 297.4, DEC = 31.1 (J2000 degrees,
equivalent to 19 h 49 m, 31 d 08 '), with an uncertainty
of 1 degrees (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which we have characterized as a core-plus-tail model, with 90% of
GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg
systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The trigger resulted in an Autonomous Repoint Request (ARR)
by the GBM Flight Software owing to the high peak flux
of the GRB. This ARR was accepted and the spacecraft slewed to the GBM
in-flight location. The initial angle from the Fermi LAT boresight to
the GBM ground location is 30 degrees.

The GBM light curve consists of two separate peaks
with a duration (T90) of about 117 s (50-300 keV).
The time-averaged spectrum from T0-5 s to T0+150 s is
adequately fit by a Band function with Epeak = 241 +/- 11 keV,
alpha = -1.05 +/- 0.02, and beta = -2.09 +/- 0.04.

The event fluence (10-1000 keV) in this time interval is
(5.45 +/- 0.01)E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+104 s in the 10-1000 keV band
is 19.2 +/- 0.7 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog."