TITLE:   GCN CIRCULAR
NUMBER:  38671
SUBJECT: GRB 241223A: Swift-XRT observations
DATE:    24/12/25 16:42:10 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

B. Sbarufatti (INAF-OAB), C. Salvaggio (INAF-OAB), S. Dichiara (PSU),
J.A. Kennea (PSU), D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester), M. Ferro (INAF-OAB) and P.A. Evans (U.
Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 241223A, collecting  2.2 ks of Photon
Counting (PC) mode data between T0+20.5 ks and T0+99.8 ks. 

No X-ray sources have been detected at the position of the GOTO optical
source (GCN Circ. 38655). The 3-sigma upper limit in the field ranges
from ~0.005 to ~0.006 ct s^-1, corresponding to a 0.3-10 keV observed
flux of 2.0e-13 to 2.5e-13 erg cm^-2 s^-1 (assuming a typical GRB
spectrum).

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021749.

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