GCN Circular 16787
Subject
GRB 140906A - Fermi GBM Detection
Date
2014-09-07T09:55:02Z (11 years ago)
From
Oliver Roberts at UCD/Fermi <oliver.roberts@ucd.ie>
O.J. Roberts (UCD), V. Pelassa and V. Connaughton (UAH) report on
behalf of the Fermi GBM Team:
At 04:11:38.70 UT on the 6th of September 2014, the Fermi Gamma-Ray
Burst Monitor triggered and located GRB 140906A
(trigger 431669501/140906175).
The angle from the Fermi LAT boresight is 90 degrees.
The on-ground calculated location, using the GBM trigger data, is
RA = 248.4, DEC = +49.5 (J2000 degrees, equivalent to
+16h 33m, +49d 30'), with an uncertainty of 7.7 degrees (radius,
1-sigma containment, statistical only; there is additionally a
systematic error which is currently estimated to be 2 to 3 degrees).
Early follow-up observations of the GBM location error box by the
intermediate Palomar Transient Factory yielded two possible optical
counterparts (Singer et al 2014, GCN 16786).
The GBM light curve consists of a single peak followed by a fainter
tail, with a duration (T90) of 39s (50-300 keV).
The time-averaged spectrum from T0-6.1 s to T0+13.3 s (interval of
brightest emission) is best fit by a power law function with an
exponential high-energy cutoff. The power law index is -1.2 +/- 0.2
and the cutoff energy, parameterized as Epeak, is 127 +/- 33 keV.
The event fluence (10-1000 keV) in this time interval is
(1.90 +/- 0.25)E-06 erg/cm^2. The 1.024-sec peak photon flux measured
starting from T0+1.216 s in the 10-1000 keV band
is 3.1 +/- 0.3 ph/s/cm^2.
The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog.