GCN Circular 37270
Subject
GRB 240824B: Swift-XRT afterglow detection
Date
2024-08-25T13:38:49Z (4 months ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
J.A. Kennea (PSU), D.N. Burrows (PSU), J.P. Osborne (U. Leicester),
K.L. Page (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC &
INAF-OAR), V. D'Elia (SSDC & INAF-OAR), S. Dichiara (PSU) and P.A.
Evans (U. Leicester) reports on behalf of the Swift-XRT team:
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.