TITLE: GCN CIRCULAR NUMBER: 38599 SUBJECT: GRB 241217A: Swift-XRT afterglow detection DATE: 24/12/17 23:30:07 GMT FROM: Maia Williams at PSU <mjw6837@psu.edu> M. A. Williams (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), S. Dichiara (PSU), J.A. Kennea (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the SVOM/ECLAIRs-detected burst GRB 241217A. We searched for X-ray sources in 1.4 ks of Photon Counting (PC) mode data. The total exposure at the position of the afterglow (see below) is 1.4 ks, obtained between T0+2.2 ks and T0+7.6 ks. An uncatalogued X-ray source is detected within the estimated 3-sigma SVOM/ECLAIRs error region (6.8 arcmin) and is above the RASS 3-sigma upper limit at this position and fading with 5.3 sigma significance, and is therefore likely the GRB afterglow. Using 1404 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 = 84.15110, -25.29680 which is equivalent to: RA (J2000): 05h 36m 36.26s Dec(J2000): -25d 17' 48.5" with an uncertainty of 2.5 arcsec (radius, 90% confidence). This position is 1.7 arcmin from the SVOM/ECLAIRs position. The peak count rate is 36 (±6) ct s^-1 (0.3 - 10 keV). View this GCN Circular online at https://gcn.nasa.gov/circulars/38599. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...