TITLE:   GCN CIRCULAR
NUMBER:  36970
SUBJECT: GRB 240727B: Swift-XRT observations
DATE:    24/07/29 08:50:31 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), C.
Salvaggio (INAF-OAB), 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,
Swift/BAT-GUANO and Astrosat/CZTI detected burst GRB 240727B (Fletcher
et al. 2024, GCN 36949; Ronchini et al. 2024, GCN 36945; Waratkar et
al. 2024, GCN 36943),  collecting 4.9 ks of Photon Counting (PC) mode
data between T0+33.5 ks and T0+52.2 ks. 

No X-ray sources have been detected within 296 arcsec of the
Swift/BAT-GUANO position. The 3-sigma upper limit in the field is 0.003
ct  s^-1, corresponding to a 0.3-10 keV observed flux of 1.0e-13 erg
cm^-2 s^-1 (assuming a typical GRB spectrum).

Three uncatalogued sources were detected too far from the GRB position
to be likely afterglow candidates.

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/00021701.

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