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GCN Circular 28458

Subject

GRB 200919A: Swift-BAT refined analysis

Date

2020-09-19T17:27:57Z (4 years ago)

From

Amy Lien at GSFC <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), 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-240 to T+962 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 200919A
(trigger #996503) (Ukwatta et al., GCN Circ. 28454Not found
 
 
).
The BAT ground-calculated position is
RA, Dec = 168.899, 32.456 deg which is
   RA(J2000)  =  11h 15m 35.7s
   Dec(J2000) = +32d 27' 21.8"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 62%.

The mask-weighted light curve shows several overlapping pulses
that start at ~T-60 s and end at ~T+25 s. The main peak
occurs at ~T+5 s. T90 (15-350 keV) is 76.0 +- 6.9 sec
(estimated error including systematics).

The time-averaged spectrum from T-61.47 to T+24.54 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 2.13 +- 0.14.  The fluence in the 15-150 keV band
is 1.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+4.30 sec in the 15-150 keV band is 1.2 +- 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/996503/BA/