////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  28406
SUBJECT: GRB 200909B: Swift detection of a burst
DATE:    20/09/09 23:26:50 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

A. Melandri (INAF-OAB), M. G. Bernardini (INAF-OAB),
J. A. Kennea (PSU), N. J. Klingler (PSU), N. P. M. Kuin (UCL-MSSL),
K. L. Page (U Leicester), D. M. Palmer (LANL) and
T. Sbarrato (INAF-OAB) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 23:17:10 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 200909B (trigger=995288).  Swift did not slew to the
location due to an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 175.176, -31.179 which is 
   RA(J2000) = 11h 40m 42s
   Dec(J2000) = -31d 10' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single complex peak
structure with a duration of about 40 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 03:23 UT on 2020 November 09. There will thus be no XRT
or UVOT data for this trigger before this time. 

Burst Advocate for this burst is A. Melandri (andrea.melandri AT brera.inaf.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)

////////////////////////////////////////////////////////////////////////
TITLE:   GCN CIRCULAR
NUMBER:  28408
SUBJECT: GRB 200909B: Swift-BAT refined analysis
DATE:    20/09/10 12:14:36 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

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
level.
  
The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/995288/BA/