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GCN Circular 14361

Subject
GRB 130408A: Swift detection of a burst
Date
2013-04-08T22:11:30Z (11 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
A. Y. Lien (NASA/GSFC/ORAU), W. H. Baumgartner (GSFC/UMBC),
D. N. Burrows (PSU), N. Gehrels (NASA/GSFC), J. A. Kennea (PSU),
D. Malesani (DARK/NBI), V. Mangano (INAF-IASFPA),
C. Pagani (U Leicester), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Swift Team:

At 21:51:38 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130408A (trigger=553132).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 134.401, -32.361 which is 
   RA(J2000) = 08h 57m 36s
   Dec(J2000) = -32d 21' 37"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 12 sec.  The peak count rate
was ~3914 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 21:54:08.6 UT, 149.9 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 134.40809, -32.36136 which is
equivalent to:
   RA(J2000)  = 08h 57m 37.94s
   Dec(J2000) = -32d 21' 40.9"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 21 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.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.98
x 10^21 cm^-2 (Kalberla et al. 2005). 

UVOT data analysis is not available at this time. 

Burst Advocate for this burst is A. Y. Lien (yarleen AT gmail.com). 
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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