TITLE:   GCN CIRCULAR
NUMBER:  13997
SUBJECT: GRB 121125A: Fermi GBM Observation
DATE:    12/11/25 21:08:30 GMT
FROM:    Sinead McGlynn at Excellence Cluster/TUM  <smcglynn@tum.de>

Sinead McGlynn (MPE/TUM)
reports on behalf of the Fermi GBM Team:

"At 08:32:29.63 UT on 25 Nov 2012, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 121125A (trigger 375525152/121125356), which was also detected by the Swift/BAT
(Barthelmy et al. 2012, GCN 13996). The GBM on-ground location is consistent with the Swift/UVOT afterglow candidate position (Barlow et al. 2012, GCN 13993).

The on-ground calculated location, using the GBM trigger
data, is RA = 229.30, DEC = +54.14 (J2000 degrees,
equivalent to 15h 17m 12s, 54d 08' 24"), with an uncertainty
of 2.22 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 37 degrees.

The GBM light curve shows/consists of several pulses
with a duration (T90) of about 50 s (50-300 keV).
The time-averaged spectrum from T0-11.3 s to T0+49.1 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.38 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 196 +/- 26 keV.

The event fluence (10-1000 keV) in this time interval is
(9.5 +/- 0.4)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+32 s in the 10-1000 keV band
is 4.2 +/- 0.3 ph/s/cm^2.

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