TITLE:   GCN CIRCULAR
NUMBER:  28705
SUBJECT: GRB 201020A: Swift-BAT refined analysis 
DATE:    20/10/20 20:08:10 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

T. Sakamoto (AGU), E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC), 
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-60 to T+243 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 201020A (trigger #1000926)
(Ambrosi et al., GCN Circ.28696).  The BAT ground-calculated position is
RA, Dec = 261.239, 31.428 deg which is 
  RA(J2000)  =  17h 24m 57.4s 
  Dec(J2000) = +31d 25' 41.8" 
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 90%.

The mask-weighted light curve shows a single symmetrical peak starting at ~T+8 sec,
peaking at T+17 sec, and decaying to background by T+26 sec.
T90 (15-350 keV) is 14.17 +- 4.68 sec (estimated error including systematics).

The time-averaged spectrum from T+8.23 to T+30.17 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
2.25 +- 0.14.  The fluence in the 15-150 keV band is 9.2 +- 0.7 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+17.17 sec in the 15-150 keV band
is 2.1 +- 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/1000926/BA/