[vsnet-grb-info 19465] GRB 170531A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  21185
SUBJECT: GRB 170531A: Swift-BAT refined analysis
DATE:    17/06/01 16:17:56 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), P.A. Evans (U Leicester),
H. A. Krimm (NSF/USRA), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(i.e. the Swift-BAT team):

Using the data set from T-65 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 170531A (trigger #755343)
(Evans et al., GCN Circ. 21170).  The BAT ground-calculated position is
RA, Dec = 121.218, -14.017 deg which is
  RA(J2000)  =  08h 04m 52.4s
  Dec(J2000) = -14d 00' 59.7"
with an uncertainty of 2.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

The mask-weighted light curve shows a weak pulse that starts ~T-10 s and
ends at ~T+25 s. T90 (15-350 keV) is 26.74 +- 7.94 sec (estimated error
including systematics).

The time-averaged spectrum from T-13.24 to T+25.78 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.22 +- 0.28.  The fluence in the 15-150 keV band is 7.5 +- 1.2 x 10^-7 erg/cm2.
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/755343/BA/