TITLE: GCN CIRCULAR NUMBER: 11488 SUBJECT: GRB 101224A: Swift-XRT refined Analysis DATE: 10/12/24 16:46:07 GMT FROM: Claudio Pagani at U of Leicester C. Pagani (U. Leicester) and H. A. Krimm (CRESST/GSFC/USRA) reports on behalf of the Swift-XRT team: We have analysed 7.6 ks of XRT data for GRB 101224A (Krimm et al. GCN Circ. 11484), from 86 s to 24.5 ks after the BAT trigger. The data are entirely in Photon Counting (PC) mode. Using 1245 s of PC mode data and 1 UVOT images, we find an enhanced XRT position (using the XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue): RA, Dec = 285.92460, +45.71350 which is equivalent to: RA (J2000): 19h 03m 41.91s Dec(J2000): +45d 42' 48.5" with an uncertainty of 3.2 arcsec (radius, 90% confidence). The afterglow is detected during the first orbit with 12 background subtracted source counts in 1.3 ks of PC data, at a count rate of 1.0 x 10^-2 counts s^-1, while it's not detected in the following orbits (1 background subtracted source count in 6.3 ks of PC data), for a 3 sigma upper limit of 1.4 x 10^-3 counts s^-1 A spectrum formed from the PC mode data can be fitted with an absorbed power-law with a photon spectral index of 3.1 (+/-1.4). The best-fitting absorption column is 1.1 (+3.5, -0.6) x 10^21 cm^-2, consistent with the Galactic value of 4.4 x 10^20 cm^-2 (Kalberla et al. 2005). The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor deduced from this spectrum is 2.9 x 10^-11 (5.1 x 10^-11) erg cm^-2 count^-1. A summary of the PC-mode spectrum is thus: Total column: 1.1 (+3.5, -0.6) x 10^21 cm^-2 Galactic foreground: 4.4 x 10^20 cm^-2 Excess significance: <1.6 sigma Photon index: 3.1 (+/-1.4) The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00440955. This circular is an official product of the Swift-XRT team.