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GCN Circular 14650

Subject
GRB 130515A: Swift detection of a short burst
Date
2013-05-15T01:35:00Z (11 years ago)
From
David Palmer at LANL <palmer@lanl.gov>
D. Malesani (DARK/NBI), S. D. Barthelmy (GSFC),
N. Gehrels (NASA/GSFC), D. Grupe (PSU), S. T. Holland (STScI),
J. A. Kennea (PSU), C. B. Markwardt (NASA/GSFC), D. M. Palmer (LANL),
B. Sbarufatti (INAF-OAB/PSU), M. H. Siegel (PSU), C. A. Swenson (PSU),
T. N. Ukwatta (MSU) and B.-B. Zhang (PSU) report on behalf of the
Swift Team:

At 01:21:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130515A (trigger=555880).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 283.422, -54.281 which is 
   RA(J2000) = 18h 53m 41s
   Dec(J2000) = -54d 16' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single
short peak with a duration of about 0.6 sec.  The peak count rate
was ~13000 counts/sec (15-350 keV), at ~0.1 sec after the trigger. 

The XRT began observing the field at 01:22:32.9 UT, 75.2 seconds after
the BAT trigger. Using promptly downlinked data we find a faint uncatalogued
X-ray source with an enhanced position: RA, Dec 283.4405, -54.2794
which is equivalent to:
   RA(J2000)  = 18h 53m 45.72s
   Dec(J2000) = -54d 16' 45.9"
with an uncertainty of 3.1 arcseconds (radius, 90% containment). This
location is 39 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 5.79
x 10^20 cm^-2 (Kalberla et al. 2005). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 78 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.07. 

Burst Advocate for this burst is D. Malesani (malesani AT dark-cosmology.dk). 
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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