GCN Circular 38098
Subject
GRB 241105A: Swift-XRT afterglow detection
Date
2024-11-06T11:56:11Z (2 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
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.