D. Kocevski (NASA/GSFC/ORAU), S. D. Barthelmy (GSFC),
W. H. Baumgartner (GSFC/UMBC), M. G. Bernardini (INAF-OAB),
D. N. Burrows (PSU), S. B. Cenko (GSFC), P. D'Avanzo (INAF-OAB),
V. D'Elia (ASDC), P. A. Evans (U Leicester), N. Gehrels (NASA/GSFC),
S. T. Holland (STScI), J. A. Kennea (PSU),
H. A. Krimm (CRESST/GSFC/USRA), A. Y. Lien (NASA/GSFC/ORAU),
D. Malesani (DARK/NBI), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), K. L. Page (U Leicester), D. M. Palmer (LANL),
M. H. Siegel (PSU) and R. L. C. Starling (U Leicester) report on
behalf of the Swift Team:
At 15:12:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 131202A (trigger=579982). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 344.056, -21.658 which is
RA(J2000) = 22h 56m 13s
Dec(J2000) = -21d 39' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve showed a single-peaked
structure with a duration of about 30 sec. The peak count rate
was ~1200 counts/sec (15-350 keV), at ~2 sec after the trigger.
The XRT began observing the field at 15:14:02.9 UT, 113.7 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 344.0540,
-21.6627 which is equivalent to:
RA(J2000) = 22h 56m 12.96s
Dec(J2000) = -21d 39' 45.6"
with an uncertainty of 2.3 arcseconds (radius, 90% containment). This
location is 18 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 in excess of the Galactic value (2.29 x
10^20 cm^-2, Kalberla et al. 2005), with an excess column of 4.3
(+3.70/-2.92) x 10^21 cm^-2 (90% confidence).
UVOT took a finding chart exposure of 150 seconds with the White filter
starting 116 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
Burst Advocate for this burst is D. Kocevski (daniel.kocevski AT 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.)