TITLE: GCN CIRCULAR NUMBER: 36063 SUBJECT: GRB 240411B: Swift detection of a burst DATE: 24/04/11 16:09:02 GMT FROM: K.L. Page at U Leicester <klp5@leicester.ac.uk> T. M. Parsotan (GSFC), S. Dichiara (PSU), R. A. J. Eyles-Ferris (U Leicester), C. Gronwall (PSU), J.D. Gropp (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester), B. Sbarufatti (INAF-OAB), M. H. Siegel (PSU) and M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift Observatory Team: At 15:32:54 UT, the Swift Burst Alert Telescope (BAT) triggered and located GRB 240411B (trigger=1221183). Swift slewed immediately to the burst. No further BAT information is available at this time due to a telemetry gap. Further information will be available after the next telemetry pass over a ground station. The XRT began observing the field at approximately 15:35:54 UT, around 180 seconds after the BAT trigger. Using promptly downlinked data we find an uncatalogued X-ray source with an enhanced position: RA, Dec 231.54236, -2.14609 which is equivalent to: RA(J2000) = 15h 26m 10.17s Dec(J2000) = -02d 08' 45.9" with an uncertainty of 1.9 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 consistent with the Galactic value of 1.11 x 10^21 cm^-2 (Willingale et al. 2013). UVOT took a finding chart exposure of 150 seconds with the White filter starting 190 seconds after the BAT trigger. No credible afterglow candidate has been found in the initial data products. The 2.7'x2.7' sub-image covers none of the XRT error circle. The 8'x8' region for the list of sources generated on-board covers 100% of the XRT error circle. The list of sources is typically complete to about 18 mag. No correction has been made for the expected extinction corresponding to E(B-V) of 0.138. Burst Advocate for this burst is T. M. Parsotan (parsotat AT umbc.edu). 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/36063. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...