TITLE: GCN CIRCULAR NUMBER: 36938 SUBJECT: GRB 240727A: Swift detection of a burst DATE: 24/07/27 04:06:04 GMT FROM: David Palmer at LANL <palmer@lanl.gov> T. M. Parsotan (GSFC), K. L. Page (U Leicester), D. M. Palmer (LANL) and B. Sbarufatti (INAF-OAB) report on behalf of the Neil Gehrels Swift Observatory Team: Prior to 03:48 UTC, BAT triggered and located GRB 240727A (Trigger 1245074) and slewed to the GRB location. Due to a telemetry gap, no further BAT information will be available until the next data downlink to the ground. The XRT began observing the field at 03:48:12 UT. Using promptly downlinked data we find a bright, uncatalogued X-ray source located at RA, Dec 236.43742, 8.62001 which is equivalent to: RA(J2000) = 15h 45m 44.98s Dec(J2000) = +08d 37' 12.0" with an uncertainty of 3.5 arcseconds (radius, 90% containment). This position may be improved as more data are received; the latest position is available at https://www.swift.ac.uk/sper. A power-law fit to a spectrum formed from promptly downlinked event data gives a column density in excess of the Galactic value (3.64 x 10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.7 (+3.19/-2.66) x 10^21 cm^-2 (90% confidence). The initial flux in the 2.5 s image was 2.08e-09 erg cm^-2 s^-1 (0.2-10 keV). UVOT took a finding chart exposure of nominal 150.000 seconds with the White filter starting at 03:48:20. Automatic processing FAILED due to its reliance on BAT data for initial parameters. Burst Advocate for this burst is T. M. Parsotan (tyler.parsotan AT nasa.gov). Please contact the BA by email if you require additional information regarding Swift followup of this burst. In extremely urgent cases, after trying the Burst Advocate, you can contact the Swift PI by phone (see Swift TOO web site for information: http://www.swift.psu.edu/) View this GCN Circular online at https://gcn.nasa.gov/circulars/36938. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...