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/)