TITLE: GCN CIRCULAR NUMBER: 22165 SUBJECT: GRB 171124A: Swift-XRT observations DATE: 17/11/24 17:36:28 GMT FROM: Phil Evans at U of Leicester J.P. Osborne (U. Leicester), A. D'Ai (INAF-IASFPA), A. Melandri (INAF-OAB), P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), A. Tohuvavohu (PSU), S. J. LaPorte (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: Swift-XRT has performed follow-up observations of the Fermi/LAT-detected burst GRB 171124A (Longo et al. GCN Circ. 22156), collecting 4.6 ks of Photon Counting (PC) mode data between T0+21.8 ks and T0+33.1 ks. Four uncatalogued X-ray sources have been detected, however none of them is above the RASS limit or shows definitive signs of fading. Therefore, at the present time we cannot identify which, if any, is the afterglow. Details of these sources are given below: Source 1: RA (J2000.0): 335.42198 = 22:21:41.28 Dec (J2000.0): +35.14890 = +35:08:56.0 Error: 2.8 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (7.5 +/- 1.5)e-3 ct s^-1 Distance: 385 arcsec from Fermi/LAT position. Flux: (1.85 +/- 0.38)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 2: RA (J2000.0): 335.47618 = 22:21:54.28 Dec (J2000.0): +35.33200 = +35:19:55.2 Error: 2.3 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: 0.0243 +/- 0.0029 ct s^-1 Distance: 423 arcsec from Fermi/LAT position. Flux: (7.33 +/- 0.86)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 3: RA (J2000.0): 335.3767 = 22:21:30.42 Dec (J2000.0): +35.1638 = +35:09:49.7 Error: 4.6 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (3.52 [+1.20, -0.99])e-3 ct s^-1 Distance: 467 arcsec from Fermi/LAT position. Flux: (1.10 [+0.38, -0.31])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) Source 4: RA (J2000.0): 335.49592 = 22:21:59.02 Dec (J2000.0): +35.16340 = +35:09:48.2 Error: 2.8 arcsec (radius, 90% conf. [Enhanced position]) Count-rate: (5.6 +/- 1.3)e-3 ct s^-1 Distance: 215 arcsec from Fermi/LAT position. Flux: (2.04 +/- 0.49)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV) The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, are available at http://www.swift.ac.uk/ToO_GRBs/00020784. This circular is an official product of the Swift-XRT team.