GCN Circular 38489

T. M. Parsotan (GSFC), E. Ambrosi (INAF-IASFPA),
A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR),
J. J. DeLaunay (PSU), P. A. Evans (U Leicester),
R. A. J. Eyles-Ferris (U Leicester) and A. Melandri (INAF-OAR) report
on behalf of the Neil Gehrels Swift Observatory Team:

At 10:59:46 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 241209D (trigger=1273106).  Swift slewed immediately to the burst.
The BAT on-board calculated location is 
RA, Dec 190.111, -2.879 which is 
   RA(J2000) = 12h 40m 27s
   Dec(J2000) = -02d 52' 42"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 150 sec.  The peak count rate
was ~3200 counts/sec (15-350 keV), at ~0 sec after the trigger.

The XRT began observing the field at 11:01:20.0 UT, 93.6 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 190.1129, -2.8901 which is equivalent to:
   RA(J2000)  = 12h 40m 27.09s
   Dec(J2000) = -02d 53' 24.5"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 41 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 visibility window of the GRB was very short and no prompt
UVOT data were generated. We await the full dataset to search for any
UV/optical afterglow.

Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan 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/)