TITLE: GCN CIRCULAR NUMBER: 38098 SUBJECT: GRB 241105A: Swift-XRT afterglow detection DATE: 24/11/06 11:56:11 GMT FROM: Phil Evans at U of Leicester pae9@star.le.ac.uk

J.A. Kennea (PSU), D.N. Burrows (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), M. A. Williams (PSU) and P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the BAT/GUANO localisation of the Fermi/GBM-detected burst GRB 241105A, collecting 3.9 ks of Photon Counting (PC) mode data between T0+38.3 ks and T0+62.2 ks.

Two uncatalogued X-ray sources are detected consistent with being within 296 arcsec of the BAT/GUANO position, of which one ("Source 1") is fading with 2.2 sigma significance and thus is believed to be the GRB afterglow. Using 794 s of PC mode data and 2 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 = 66.24484, -49.75181 which is equivalent to:

RA (J2000): 04h 24m 58.76s Dec(J2000): -49d 45' 06.5"

with an uncertainty of 4.9 arcsec (radius, 90% confidence). This position is 18 arcsec from the BAT/GUANO position (DeLaunay et al., GCN Circ. 38091), and is consistent with the GOTO optical counterpart (Julakanti et al., GCN Circ. 38088).

The light curve can be modelled with a power-law decay with a decay index of alpha=3.32 (+0.05, -2.26).

If the light curve continues to decay with a power-law decay index of 3.32, the count rate at T+24 hours will be 1.8 x 10^-3 count s^-1

The results of the XRT-team automatic analysis are available at http://www.swift.ac.uk/xrt_products/00021728. The results of the full analysis of the XRT observations are available at https://www.swift.ac.uk/ToO_GRBs/00021728.

This circular is an official product of the Swift-XRT team.

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