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. View this GCN Circular online at https://gcn.nasa.gov/circulars/36970. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...