[vsnet-grb-info 20606] GRB 180510A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22704
SUBJECT: GRB 180510A: Swift-BAT refined analysis
DATE:    18/05/11 14:30:46 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), J. D. Gropp (PSU),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(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 180510A (trigger #831810)
(Gropp et al. GCN Circ. 22695).  The BAT ground-calculated position is
RA, Dec = 276.335, -31.917 deg which is
  RA(J2000)  =  18h 25m 20.5s
  Dec(J2000) = -31d 55' 00.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 37%.

The mask-weighted light curve shows a multi-peaked structure that starts at
~ T-6 s and ends at ~ T+ 65 s. The major peak occurs at ~ T+6 s. T90 (15-350 keV)
is 40.4 +- 10.4 sec (estimated error including systematics).

The time-averaged spectrum from T-6.21 to T+65.76 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index 1.06 +- 0.23,
and Epeak of 126.8 +- 52.0 keV (chi squared 54.94 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 6.2 +- 0.2 x 10^-6 erg/cm2
and the 1-sec peak flux measured from T+5.26 sec in the 15-150 keV band is
8.9 +- 0.5 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.48 +- 0.05 (chi squared 65.55 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/831810/BA/