TITLE:   GCN CIRCULAR
NUMBER:  17524
SUBJECT: GRB 150301B: Swift-BAT refined analysis
DATE:    15/03/02 05:24:04 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), W. H. Baumgartner (GSFC/UMBC),
J. R. Cummings (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),
(i.e. the Swift-BAT team):

Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 150301B (trigger #633180)
(Lien, et al., GCN Circ. 17515).  The BAT ground-calculated position is
RA, Dec = 89.159, -57.969 deg which is
  RA(J2000)  =  05h 56m 38.3s
  Dec(J2000) = -57d 58' 07.8"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.

The mask-weighted light curve shows a single-peaked structure that starts at ~ T0,
peaks at ~ T+3 s, and ends at ~ T+16 s. T90 (15-350 keV) is 12.44 +- 1.49 sec
(estimated error including systematics).

The time-averaged spectrum from T-0.34 to T+15.62 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.46 +- 0.07.  The fluence in the 15-150 keV band is 1.8 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+3.65 sec in the 15-150 keV band
is 3.0 +- 0.2 ph/cm2/sec.  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/633180/BA/