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GCN Circular 14127

Subject
GRB 130102A: Swift detection of a burst
Date
2013-01-02T18:27:44Z (11 years ago)
From
Scott Barthelmy at NASA/GSFC <scott@milkyway.gsfc.nasa.gov>
K. L. Page (U Leicester), S. D. Barthelmy (GSFC),
A. P. Beardmore (U Leicester), N. Gehrels (NASA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
F. E. Marshall (NASA/GSFC), B. Sbarufatti (INAF-OAB/PSU) and
M. H. Siegel (PSU) report on behalf of the Swift Team:

At 18:10:53 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 130102A (trigger=544784).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 311.464, +49.835 which is 
   RA(J2000)  =  20h 45m 51s
   Dec(J2000) = +49d 50' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As per usual for an image trigger, the TDRSS
lightcurve does not show anything significant. 

The XRT began observing the field at 18:12:50.3 UT, 116.5 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
311.4233, 49.8174 which is equivalent to:
   RA(J2000)  = 20h 45m 41.60s
   Dec(J2000) = +49d 49' 02.6"
with an uncertainty of 2.1 arcseconds (radius, 90% containment). This
location is 113 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 7.96
x 10^21 cm^-2 (Kalberla et al. 2005). 

The initial flux in the 2.5 s image was 5.62e-10 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 125 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 large, but uncertain extinction expected. 

We note that this event is at galactic coordinates: l = 88.33 deg, b = 4.22 
deg.  It has the characteristics of a GRB, but could be a galactic transient 
since it is close to the galactic plane. 

Burst Advocate for this burst is K. L. Page (kpa AT star.le.ac.uk). 
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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