GRB 240824B: Swift-XRT afterglow detection

Swift-XRT has performed follow-up observations of the Swift/BAT, MAXI and Fermi-GBM-detected burst GRB 240824B (GCN #37260, #37261, #37266, #37267) collecting 4.1 ks of Photon Counting (PC) mode data between T0+27.7 ks and T0+52.3 ks. Two uncatalogued X-ray sources are detected consistent with being within 296 arcsec of the Swift/BAT position, of which one ("Source 1") is fading with 2.4 sigma significance and thus is believed to be the GRB afterglow. Using 732 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 = 17.83675, +2.60999 which is equivalent to: RA (J2000): 01h 11m 20.82s Dec(J2000): +02d 36' 36.0" with an uncertainty of 4.5 arcsec (radius, 90% confidence). This position is 36 arcsec from the Swift/BAT position. The light curve can be modelled with a power-law decay with a decay index of alpha=3.1 (+0.5, -2.1). The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021705. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021705. This circular is an official product of the Swift-XRT team.