TITLE: GCN CIRCULAR NUMBER: 41783 SUBJECT: GRB 250911A: Swift-XRT observations DATE: 25/09/11 05:16:58 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> M. Perri (SSDC & INAF-OAR), P.A. Evans (U. Leicester) and J.A. Kennea (PSU) report on behalf of the Swift-XRT team: The XRT began observing the field of GRB 250911A at 02:25:07.6 UT, 3441.5 seconds after the BAT trigger. Using promptly downlinked data we find a fading, uncatalogued X-ray source located at RA, Dec 263.75102, -16.85448 which is equivalent to: RA(J2000) = 17h 35m 00.24s Dec(J2000) = -16d 51' 16.1" with an uncertainty of 3.7 arcseconds (radius, 90% containment). This location is 53 arcseconds from the BAT onboard position, within the BAT error circle. 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 (3.44 x 10^21 cm^-2, Willingale et al. 2013), with an excess column of 4.3 (+3.44/-2.88) x 10^21 cm^-2 (90% confidence). View this GCN Circular online at https://gcn.nasa.gov/circulars/41783. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...