TITLE:   GCN CIRCULAR
NUMBER:  17274
SUBJECT: GRB 150103A: Swift-BAT refined analysis
DATE:    15/01/04 01:59:55 GMT
FROM:    Jay R. Cummings at NASA/GSFC/Swift  <james.r.cummings@nasa.gov>

J. R. Cummings, S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
N. Gehrels (GSFC), H. A. Krimm (GSFC/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), J. Tueller (GSFC), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):
  
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150103A (trigger #623368) (Hagen, et al.,
GCN Circ. 17269).  The BAT ground-calculated position is
RA, Dec = 131.674, -48.896 deg which is
    RA(J2000)  =  08h 46m 41.9s
    Dec(J2000) = -48d 53' 45.2"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 67%.
  
The mask-weighted light curve shows a single broad peak.  T90 (15-350 keV) is
49.1 +- 9.8 sec (estimated error including systematics).
  
The time-averaged spectrum from T+6.06 to T+64.68 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index -0.03 +- 1.01,
and Epeak of 54.2 +- 12.8 keV (chi squared 54.70 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 8.2 +- 1.3 x 10^-07 erg/cm2
and the 1-sec peak flux measured from T+26.32 sec in the 15-150 keV band is
0.5 +- 0.2 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.61 +- 0.18 (chi squared 66.38 for 57 d.o.f.).  All the quoted errors
are at the 90% confidence level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/623368/BA/