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GCN Circular 23377

Subject
GRB 181023A: Swift-BAT refined analysis
Date
2018-10-24T01:39:15Z (6 years ago)
From
Amy Lien at GSFC <amy.y.lien@nasa.gov>
T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC),
J. R. Cummings (CPI), H. A. Krimm (NSF/USRA),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
F. E. Marshall (NASA/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 181023A (trigger #868427)
(Marshall et al., GCN Circ. 23366).  The BAT ground-calculated position is
RA, Dec = 248.322, 19.581 deg which is
  RA(J2000)  =  16h 33m 17.4s
  Dec(J2000) = +19d 34' 51.2"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.

The mask-weighted light curve shows a complex structure with some
weak overlapping pulses that starts at ~T-30 s and ends at ~T+40 s.
Note that the burst entered the BAT FOV at T-48 s, and hence there might
be additional emission beforehand. T90 (15-350 keV) is 58.0 +- 8.8 sec (estimated
error including systematics).

The time-averaged spectrum from T-27.62 to T+36.68 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.74 +- 0.24.  The fluence in the 15-150 keV band is 1.3 +- 0.2 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+32.18 sec in the 15-150 keV band
is 1.0 +- 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/868427/BA/
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