TITLE:   GCN CIRCULAR
NUMBER:  28801
SUBJECT: GRB 201027A: Swift-BAT refined analysis
DATE:    20/10/29 01:23:20 GMT
FROM:    Sibasish Laha at GSFC  <sibasish.laha@nasa.gov>

H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
S. B. Cenko (GSFC), J. R. Cummings (CPI),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
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 201027A (trigger #1002158)
(S. B. Cenko, et al., GCN Circ. 28788).  The BAT ground-calculated position is
RA, Dec = 155.954, -5.499 deg which is
   RA(J2000)  =  10h 23m 49.0s
   Dec(J2000) = -05d 29' 56.8"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 44%.

The BAT light curve showed a complex structure with a duration of about 20 sec.
T90 (15-350 keV) is 546.73 +- 420.95 sec (estimated error including systematics).

The time-averaged spectrum from T-3.86 to T+960 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.50 +- 0.00.  The fluence in the 15-150 keV band is 0.0 +- 0.0 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T-0.29 sec in the 15-150 keV band
is 1.4 +- 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/1002158/BA/