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GCN Circular 8804

Subject
GRB 090113: Swift detection of a burst
Date
2009-01-13T19:06:45Z (15 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@lheamail.gsfc.nasa.gov>
H. A. Krimm (CRESST/GSFC/USRA), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), D. N. Burrows (PSU),
P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (CRESST/USRA/GSFC), E. A. Hoversten (PSU),
J. A. Kennea (PSU), C. B. Markwardt (CRESST/GSFC/UMD),
P. T. O'Brien (U Leicester), K. L. Page (U Leicester),
A. M. Parsons (GSFC), B. A. Rowlinson (U Leicester),
T. Sakamoto (NASA/UMBC), E. Troja (INAF-IASFPA),
T. N. Ukwatta (GSFC/GWU), L. Vetere (PSU) and H. Ziaeepour (UCL-MSSL)
report on behalf of the Swift Team:

At 18:40:39 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 090113 (trigger=339852).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 32.073, +33.456 which is 
   RA(J2000)  =  02h 08m 18s
   Dec(J2000) = +33d 27' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows about 4 peaks
with a duration of about 20 sec.  The peak count rate
was ~5000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 18:41:50.1 UT, 70.9 seconds after
the BAT trigger. The onboard source-detection algorithm originally
centroided on a hot column. No other source was visible in the initial
TDRSS sub-image. We are waiting for the full Malindi dataset to detect
and localise the afterglow. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 79 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The sub-image covers 25% of the BAT
error circle.  The overlap of the 8'x8' region for the list of
sources generated on-board is 100% of the BAT error circle.  This source
list is usually complete to about 18th magnitude.  No correction
has been made for the expected extinction corresponding to E(B-V) of 0.08. 

This burst was also detected by Fermi-GBM. 

This burst is not to be confused with the BAT trigger (339853)
about 12 minutes later on the 1A 1118-61 HMXB source. 

Burst Advocate for this burst is H. A. Krimm (krimm AT milkyway.gsfc.nasa.gov). 
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.)
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