TITLE:   GCN CIRCULAR
NUMBER:  43155
SUBJECT: GRB 251215A: Swift-XRT afterglow detection
DATE:    25/12/20 11:59:19 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore
(U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A.
Melandri (INAF-OAR), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea
(PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT
team:

Swift-XRT has conducted further observations of the field of the
Swift/BAT-detected burst GRB 251215A. The observations now extend from
T0+32.0 ks to T0+383.9 ks and have a total exposure time of 9.9 ks.

Of the sources previously reported, "Source 5" is fading with >3-sigma
significance, and is therefore likely the GRB afterglow. Using 1629 s
of PC mode data and 1 UVOT image, we find an enhanced XRT position
(using the XRT-UVOT alignment and matching UVOT field sources to the
USNO-B1 catalogue): RA, Dec = 122.61893, -36.74266 which is equivalent
to:

RA (J2000): 08h 10m 28.54s
Dec(J2000): -36d 44' 33.6"

with an uncertainty of 5.7 arcsec (radius, 90% confidence). This
position is 97 arcsec from the Swift/BAT position.  The source is
fading with alpha >0.3.

The results of the XRT-team automatic analysis of the likely afterglow
are at https://www.swift.ac.uk/ToO_GRBs/00021894/Source5.php.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021894.

This circular is an official product of the Swift-XRT team.