[vsnet-grb-info 9506] GRB 100724B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10977
SUBJECT: GRB 100724B: Fermi GBM detection
DATE:    10/07/24 23:28:20 GMT
FROM:    Narayana Bhat at U Alabama/Huntsville/GBM  <Narayana.Bhat at nasa.gov>

P. N. Bhat (UAH)
reports on behalf of the Fermi GBM Team:

"At 00:42:05.98 UT on 24 July 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100724B (trigger 301624927 / 100724029).

The on-ground calculated location, using the GBM trigger
data, is RA = 124.16, DEC = 74.42 (J2000 degrees,
equivalent to 08 h 16.6 m, 74 d 25.2 '), with an uncertainty
of 1.0 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
 
The angle from the Fermi LAT boresight is 52 degrees.

GBM triggered an automatic repoint request to the Fermi
Observatory to execute a maneuver following this trigger
and track the burst location for the next 5 hours.
However due to spacecraft constraints, the slew did not
commence until 2733 s after the trigger.

This burst was also independently detected by INTEGRAL SPI-ACS.

The GBM light curve consists of several pulses
with a duration (T90) of about 111.6 s (50-300 keV).
The time-averaged spectrum from T0-5.12 s to T0+140.29 s is
best fit by a Band function with Epeak = 467.8 +15.3/-13.1 keV,
alpha = 0.84 +/- 0.01, and beta = -1.84 +/- 0.01
(Cstat 18069 for 736 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(2.44 +/- 0.006)E-04 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+52 s in the 8-1000 keV band
is 7.06 +/- 0.01 ph/s/cm^2.

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