[vsnet-grb-info 8968] GRB 100224B: Fermi GBM detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  10457
SUBJECT: GRB 100224B: Fermi GBM detection
DATE:    10/02/26 15:58:41 GMT
FROM:    Ryan Foley at MPE  <sfoley at mpe.mpg.de>

Suzanne Foley (MPE)
reports on behalf of the Fermi GBM Team:

"At 02:40:55.48 UT on 24 February 2010, the Fermi Gamma-Ray Burst Monitor
triggered and located GRB 100224B (trigger 288672057 / 100224112).

The on-ground calculated location, using the GBM trigger
data, is RA = 269.56, DEC = -17.08 (J2000 degrees,
equivalent to 17 h 58 m, -17 d 05 '), with an uncertainty
of 1.6 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 88 degrees.

The GBM light curve consists of 3 peaks
with a duration (T90) of about 77 (+/-2) s (50-300 keV)
starting at T0-5.6 s. The time-averaged spectrum from
T0-7.2 s to T0+71.7 s is well fit by a power law function
with an exponential high energy cutoff.  The power law
index is -1.36 (+0.07/-0.06) and the cutoff energy,
parameterized as Epeak, is 181.40 (+31.50/-23.60) keV
(CSTAT 591 for 361 d.o.f.).

The event fluence (8-1000 keV) in this time interval is
(1.08 +/- 0.05 )E-5 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+16.4 s in the 8-1000 keV band
is 10.7 +/- 0.3 ph/s/cm^2.


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