[vsnet-grb-info 12807] GRB 130127A: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  14154
SUBJECT: GRB 130127A: Fermi GBM detection
DATE:    13/01/28 18:54:47 GMT
FROM:    Veronique Pelassa at UAH  <vero.pelassa at gmail.com>

V. Pelassa (UAH) reports on behalf of the Fermi GBM Team:

"At 17:50:23.93 UT on 27 January 2013, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 130127A (trigger 381001826 / 130127743).

The on-ground calculated location, using the GBM trigger
data, is RA = 251.1, DEC = -17.1 (J2000 degrees,
equivalent to 16 h 44 m, -17 d 04'), with an uncertainty
of 8.5 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 27 degrees.

The GBM light curve shows a bright short peak and a fainter
tail, with a duration (T90) of about 0.45 s (50-300 keV).

The time-averaged spectrum from T0-0.064 s to T0+0.064 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.03 +/- 0.29 and
the cutoff energy, parameterized as Epeak, is 770 +/- 190 keV
(Castor statistics 751 for 725 d.o.f.).

The event fluence (10-1000 keV) in this time interval is
(4.9 +/- 0.4)E-07 erg/cm^2. The 64-msec peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band
is 7.4 +/- 0.9 ph/s/cm^2.

A Band function fits the spectrum equally well
(Castor statistics 750.29 for 724 d.o.f.) with Epeak= 700 +/- 210 keV,
alpha = 0.03 +/- 0.34 and beta = -2.4 +/- 0.7.


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