TITLE:   GCN CIRCULAR
NUMBER:  35810
SUBJECT: GRB 240225B: Swift-XRT observations
DATE:    24/02/26 22:22:37 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAR), T. Sbarrato (INAF-OAB),
J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), D.N. Burrows (PSU), J.P.
Osborne (U. Leicester), K.L. Page (U. Leicester) and P.A. Evans (U.
Leicester) and A. A. Breeveld (UCL-MSSL) reports on behalf of the
Swift-XRT and the Swift-UVOT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 240225B in a series of observations tiled on the sky. The
total exposure time is 1.8 ks, distributed over 7 tiles; the maximum
exposure at a single sky location was 693 s. The data were collected
between T0+29.1 ks and T0+30.9 ks, and are entirely in Photon Counting
(PC) mode. 

Two uncatalogued X-ray sources are detected, of which one ("Source 1")
is above the RASS 3-sigma upper limit at this position. The position of
this source is RA, Dec=128.3629, +27.0746 which is equivalent to:

RA (J2000): 08:33:27.11
Dec(J2000): +27:04:28.5

with an uncertainty of 4.4 arcsec (radius, 90% confidence).  This
position is 25.3 arcmin from the MAXI position. At the present time the
light curve of Source 1 shows no signs of fading and we can not 
confirm this source as the GRB afterglow.

The results of the full analysis of the tiled XRT observations are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00124.

Source 1 was out of the field of view for UVOT so we can't say anything
about optical properties.

This circular is an official product of the Swift team.