[vsnet-grb-info 12033] GRB 120707A: Fermi GBM Detection of a Bright Burst

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13422
SUBJECT: GRB 120707A: Fermi GBM Detection of a Bright Burst
DATE:    12/07/08 05:55:26 GMT
FROM:    George A. Younes at USRA/NASA/MSFC  <younes.ge at gmail.com>

George Younes (NASA/USRA), report on behalf of the Fermi GBM Team:

"At 19:12:17.42 UT on 07 July 2012, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 120707A (trigger 363381140 / 120707.800).
The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 291.06, Dec = -34.44 (J2000 degrees, equivalent to
J2000 19h 24m, -34d 26'), with a statistical uncertainty of 1.0 degrees
(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 159 degrees.

The burst triggered an ARR (Automatic Repointing Request), causing 
Fermi to slew so the LAT would point to the source.  Because the burst 
was close to the Earth's limb, this maneuver was delayed, placing the 
GRB position near the LAT boresight starting about 1000 s after the GBM trigger time.

The GBM light curve shows a strong central  pulse with fainter wings
with a duration (T90) of about 50 s (50-300 keV). The time-averaged
spectrum from T0-3 to T0+57 s is best fit by a Band function with Epeak = 
174 +/- 7 keV, alpha = -1.17 +/- 0.03, and beta = -2.31 +/- 0.03.

The fluence (10-1000 keV) in this time interval is (1.1 +/- 0.007)E-4 erg/cm^2.
The 1-sec peak photon flux measured starting from T0+29.1 s in the 10-1000 keV band
is 62 +/- 2 ph/s/cm^2.

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