TITLE:   GCN CIRCULAR
NUMBER:  10651
SUBJECT: GRB 100423A: Swift detection of a burst
DATE:    10/04/23 00:48:05 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

M. C. Stroh (PSU), P. A. Evans (U Leicester), J. M. Gelbord (PSU),
S. T. Holland (CRESST/USRA/GSFC), J. A. Kennea (PSU),
C. B. Markwardt (CRESST/GSFC/UMD), D. M. Palmer (LANL),
M. H. Siegel (PSU), M. A. Stark (PSU) and L. Vetere (PSU) report on
behalf of the Swift Team:

At 00:34:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 100423A (trigger=420247).  Swift could not slew to
this source because it was too close to the Moon (~10 degrees). 
The BAT on-board calculated location is 
RA, Dec 136.477, +21.479 which is 
   RA(J2000) = 09h 05m 54s
   Dec(J2000) = +21d 28' 46"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed single peak
FRED with a duration of at least 100 sec, and a brief precursor spike
at T-0.5.  The peak count rate was ~21000 counts/sec (15-350 keV), 
at ~0 sec after the trigger. 

Due to a Moon constraint, Swift could not slew to observe this
source with the XRT and UVOT.  The source will become observable
early on April 24 UT. 

Burst Advocate for this burst is M. C. Stroh (stroh AT astroh.org). 
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/too.html.)