Skip to main content
Testing. You are viewing the public testing version of GCN. For the production version, go to
New Announcement Feature, Code of Conduct, Circular Revisions. See news and announcements

GCN Circular 28408

GRB 200909B: Swift-BAT refined analysis
2020-09-10T12:14:36Z (4 years ago)
Takanori Sakamoto at AGU <>
S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF), A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
A. Melandri (INAF-OAB), 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 200909B (trigger #995288)
(Melandri, et al., GCN Circ. 28406).  The BAT ground-calculated position is
RA, Dec = 175.171, -31.199 deg which is
    RA(J2000)  =  11h 40m 41.1s
    Dec(J2000) = -31d 11' 54.7"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 35%.
The mask-weighted light curve shows a single peak that stars at T-6 sec,
peaks at T+1 sec, and ends at T+20 sec.  A hint of an extended emission
is visible until T+40 sec.  T90 (15-350 keV) is 16.9 +- 2.2 sec (estimated error
including systematics).
The time-averaged spectrum from T-5.6 to T+14.2 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.60 +- 0.14.  The fluence in the 15-150 keV band is 1.2 +- 0.1 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T-0.44 sec in the 15-150 keV band
is 1.3 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
The results of the batgrbproduct analysis are available at
Looking for U.S. government information and services? Visit