[vsnet-grb-info 10038] Trigger 441015: Swift detection of a possible burst or transient

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  11493
SUBJECT: Trigger 441015: Swift detection of a possible burst or transient
DATE:    10/12/25 19:19:33 GMT
FROM:    Judith Racusin at GSFC  <judith.racusin at nasa.gov>

J. L. Racusin (NASA/GSFC), A. P. Beardmore (U Leicester),
S. Campana (INAF-OAB), M. M. Chester (PSU),
J. R. Cummings (NASA/UMBC), N. Gehrels (NASA/GSFC),
J. M. Gelbord (PSU), S. T. Holland (CRESST/USRA/GSFC),
J. A. Kennea (PSU), H. A. Krimm (CRESST/GSFC/USRA),
O. M. Littlejohns (U Leicester), K. L. Page (U Leicester),
B. Sbarufatti (INAF-OAB/IASFPA) and M. H. Siegel (PSU) report on
behalf of the Swift Team:

At 18:37:45 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 101225A (trigger=441015).  Swift slewed immediately to the burst. 
However, given that this was a 1088-second image trigger, the time from the
trigger time (at the start of the image interval) to the XRT observation is 
over 23 minutes.  The BAT on-board calculated location is 
RA, Dec 0.234, +44.602 which is 
   RA(J2000) = 00h 00m 56s
   Dec(J2000) = +44d 36' 06"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Since this was an image trigger, the 
currently available BAT light curve does not show significant structure. 

The XRT began observing the field at 19:00:48.5 UT, 1383.0 seconds
after the BAT trigger. XRT found a bright, uncatalogued X-ray source
located at RA, Dec 0.1992, +44.6017 which is equivalent to:
   RA(J2000)  = 00h 00m 47.80s
   Dec(J2000) = +44d 36' 06.1"
with an uncertainty of 5.1 arcseconds (radius, 90% containment). This
location is 89 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. 

UVOT data products have not been received at this time. 

The BAT trigger was an unusually long image trigger.  Due to the 
relative proximity to the Galactic plane (l=113.55,b=-17.35), and lack
of fading  information from XRT at this time, we are unsure if this
trigger is a  GRB or transient.  We will report as more information is
available. 

Burst Advocate for this burst is J. L. Racusin (judith.racusin 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.)