GCN Circular 38547

R. Gupta (NASA GSFC), C. Gronwall (PSU), K. L. Page (U Leicester) and
T. Sakamoto (AGU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 02:19:00 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241213A (trigger=1274039).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 116.148, +35.280 which is 
   RA(J2000) = 07h 44m 35s
   Dec(J2000) = +35d 16' 49"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a bright peak 
with a duration of about 15 sec.  The peak count rate
was ~9500 counts/sec (15-350 keV), at ~0 sec after the trigger.

The XRT began observing the field at 02:25:36.0 UT, 395.9 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 116.17145,
35.27944 which is equivalent to:
   RA(J2000)  = 07h 44m 41.15s
   Dec(J2000) = +35d 16' 46.0"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 68 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 https://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 (6.66 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 5
(+2.07/-1.84) x 10^21 cm^-2 (90% confidence).

UVOT took a finding chart exposure of 250 seconds with the U filter starting
318 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 none of the
XRT error circle. 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 18.0 mag. No correction has been made for the expected extinction
corresponding to E(B-V) of 0.060.

Burst Advocate for this burst is R. Gupta (rahulbhu.c157 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/)