GCN Circular 20338
A. Cholden-Brown (PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team: We have analysed 4.9 ks of XRT data for GRB 161224A, from 28.3 ks to 52.2 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. A fading X-ray source is found in the BAT error region. Using 617 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 = 204.81579, -18.02909 which is equivalent to: RA (J2000): 13h 39m 15.79s Dec(J2000): -18d 01' 44.7" with an uncertainty of 4.1 arcsec (radius, 90% confidence). The light curve can be modelled with a power-law decay with a decay index of alpha=2.8 (+0.8, -2.1). If the light curve continues to decay with a power-law decay index of 2.8, the count rate at T+24 hours will be 8.4 x 10^-4 count s^-1 The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00728268. This circular is an official product of the Swift-XRT team.