[vsnet-grb-info 14101] GRB 131024C: ICSP discovery of a burst in X-rays by balloon borne study

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  15415
SUBJECT: GRB 131024C: ICSP discovery of a burst in X-rays by balloon borne  study
DATE:    13/10/31 11:52:50 GMT
FROM:    Sandip K. Chakrabarti at S.N. Bose Nat. Centre for Basic Sci.  <chakraba at bose.res.in>

GRB 131024C: ICSP discovery of a burst in X-rays by balloon borne study

Sandip K. Chakrabarti (SNBNCBS, ICSP & ICRANET), D. Bhowmick (ICSP), S.
Chakraborty (ICSP), R. Sarkar (ICSP)

Indian Centre for Space Physics (ICSP)  balloon borne Dignity-45 mission
with a 2 inch diameter (~ 20 sq cm)
Bicron (NaI) X-ray detector was surveying a slice of the sky with a 40
degree FOV circular  collimator
(transparent >100keV), tilted at 40 degree with the zenith. At 07:48:54
UT, it detected a GRB with a location
within a 20 degree radius circle centered at around

   RA(J2000) = 13h 27m 59s
   Dec(J2000) = + 52d 44m 43.7s

The peak count (at 07:48:54s UT) rate was ~ 740/sec (20-100keV) after a
possible precursor 4s earlier. The total duration,
with weaker peaks is about 10 seconds. The light curve, 2s average
spectrum at the peak, the dynamical spectrum, and
the approximate location of the GRB are given in the webpage:
http://www.csp.res.in/ICSP-WEB/Balloon/Near%20space%20Exploration.html

Our time resolution was one second, so finer time stamp was not possible.
The balloon altitude at the time of observation was 34km.
Hence there was a severe absorption at the lower energy of the spectrum.
The flux at the peak is 1.53x10^-6 ergs/cm^2/s  (20-100keV).

We verified with FERMI and SWIFT teams that the satellites were on the
other side of the sky and thus both have missed it.