TITLE: GCN CIRCULAR NUMBER: 43155 SUBJECT: GRB 251215A: Swift-XRT afterglow detection DATE: 25/12/20 11:59:19 GMT FROM: Phil Evans at U of Leicester <pae9@star.le.ac.uk> J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), A. D'Ai (INAF-IASFPA), S. Campana (INAF-OAB), A. Melandri (INAF-OAR), S. Lanava (PSU), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team: Swift-XRT has conducted further observations of the field of the Swift/BAT-detected burst GRB 251215A. The observations now extend from T0+32.0 ks to T0+383.9 ks and have a total exposure time of 9.9 ks. Of the sources previously reported, "Source 5" is fading with >3-sigma significance, and is therefore likely the GRB afterglow. Using 1629 s of PC mode data and 1 UVOT image, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 122.61893, -36.74266 which is equivalent to: RA (J2000): 08h 10m 28.54s Dec(J2000): -36d 44' 33.6" with an uncertainty of 5.7 arcsec (radius, 90% confidence). This position is 97 arcsec from the Swift/BAT position. The source is fading with alpha >0.3. The results of the XRT-team automatic analysis of the likely afterglow are at https://www.swift.ac.uk/ToO_GRBs/00021894/Source5.php. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021894. This circular is an official product of the Swift-XRT team. View this GCN Circular online at https://gcn.nasa.gov/circulars/43155. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...