[vsnet-grb-info 11708] GRB 120323A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  13099
SUBJECT: GRB 120323A: Fermi GBM detection
DATE:    12/03/24 16:02:47 GMT
FROM:    David Gruber at MPE  <dgruber at mpe.mpg.de>

David Gruber (MPE) and Valerie Connaughton (UAH)
report on behalf of the Fermi GBM Team:

"At 12:10:19.72 UT on 23 March 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 120323A (trigger 354197421 / 120323507).

The on-ground calculated location, using the GBM trigger
data, is RA = 346.8, DEC = 27.2 (J2000 degrees,
equivalent to 23 h 07 m, 27 d 12 '), with an uncertainty
of 1 degree (radius, 1-sigma containment,
statistical only; there is additionally a systematic
error which is currently estimated to be 2 to 3 degrees).
(This location has been updated from an earlier GCN notice).

The angle from the Fermi LAT boresight is 43 degrees.
Moreover, this burst was bright enough to result in a Fermi spacecraft
autonomous rapid repoint (ARR) maneuver.

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

The GBM light curve consists of a very bright, double-peaked FRED-like pulse
with a duration (T90) of about 0.446 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.512 s is
best fit by a Band function with Epeak = 64.8 +/- 3.8 keV,
alpha = -0.82 +/- 0.07, and beta = -2.01 +/- 0.02.

The event fluence (10-1000 keV) in this time interval is
(1.080 +/- 0.002)E-05 erg/cm^2. The 0.064-sec peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band
is 574.7 +/- 7.8 ph/s/cm^2. 
This peak flux is the highest of the mission to date.

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