[vsnet-grb-info 19276] GRB 170330A: Swift-BAT refined analysis

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  20968
SUBJECT: GRB 170330A: Swift-BAT refined analysis
DATE:    17/04/01 06:16:03 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien at nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), P. D'Avanzo (INAF-OAB),
N. Gehrels (GSFC), H. A. Krimm (NSF/USRA),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
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 170330A (trigger #744773)
(D'Avanzo et al., GCN Circ. 20944).  The BAT ground-calculated position is
RA, Dec = 283.331, -13.458 deg which is
  RA(J2000)  =  18h 53m 19.4s
  Dec(J2000) = -13d 27' 29.2"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 46%.

The mask-weighted light curve shows a multi-peaked structure that lasts
until ~T+126 s, with the main peak occurs around ~T-135 s. The burst came
into the BAT field of view at ~T-170 s during a pre-planned spacecraft slew.
Therefore, the burst emission might have started before ~T-170 s.
T90 (15-350 keV) is 144.73 +- 3.51 sec (estimated error including systematics).

The time-averaged spectrum from T-143.2 to T+126.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.38 +- 0.09.  The fluence in the 15-150 keV band is 5.6 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-134.71 sec in the 15-150 keV band
is 4.5 +- 0.3 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/744773/BA/