M. J. Page (UCL-MSSL), S. D. Barthelmy (GSFC), N. Gehrels (NASA/GSFC),
H. A. Krimm (CRESST/GSFC/USRA), K. L. Page (U Leicester) and
M. H. Siegel (PSU) report on behalf of the Swift Team:
At 06:39:24 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 131229A (trigger=582374). Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 85.236, -4.431 which is
RA(J2000) = 05h 40m 57s
Dec(J2000) = -04d 25' 52"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty). The BAT light curve shows multiple peaks
with a total duration of about 25 sec. The peak count rate
was ~27,000 counts/sec (15-350 keV), at ~13 sec after the trigger.
The XRT began observing the field at 06:40:57.9 UT, 93.8 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 85.2327, -4.3962 which is equivalent to:
RA(J2000) = +05h 40m 55.85s
Dec(J2000) = -04d 23' 46.3"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 125 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy.
The initial flux in the 2.5 s image was 3.18e-09 erg cm^-2 s^-1 (0.2-10
UVOT took a finding chart exposure of 250 seconds with the U filter starting
158 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. No correction has been made for the expected extinction corresponding
to E(B-V) of 0.29.
Burst Advocate for this burst is M. J. Page (m.page AT ucl.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.)