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GCN Circular 11773

Subject
GRB 110305A: Swift detection of a burst
Date
2011-03-05T07:00:46Z (13 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
D. Grupe (PSU), W. H. Baumgartner (GSFC/UMBC), J. M. Gelbord (PSU),
E. A. Hoversten (PSU), C. B. Markwardt (NASA/GSFC),
D. M. Palmer (LANL), E. Sonbas (GSFC/USRA/Adiyaman Univ.),
M. C. Stroh (PSU) and C. W. Wolf (PSU) report on behalf of the Swift
Team:

At 06:38:01 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 110305A (trigger=448229).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 260.877, -15.790 which is 
   RA(J2000) = 17h 23m 31s
   Dec(J2000) = -15d 47' 23"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a flat-topped
structure with a superimposed short spike and an overall
duration of about 10 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 06:39:50.2 UT, 109.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 260.8809, -15.8023
which is equivalent to:
   RA(J2000)  = 17h 23m 31.42s
   Dec(J2000) = -15d 48' 08.2"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 46 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at http://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.73
x 10^21 cm^-2 (Kalberla et al. 2005). 

Due to bright stars in the field there will be no white finding chart
for this field.  UVOT information is not available at this time. 

Burst Advocate for this burst is D. Grupe (grupe AT astro.psu.edu). 
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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