GCN Circular 43388
Subject
GRB 260111A: Swift-XRT observations
Event
Date
2026-01-13T11:01:35Z (14 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
S. Lanava (PSU), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR), V. D'Elia
(SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), S. Dichiara (PSU), J.A.
Kennea (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-GUANO
(Ronchini et al., GCN 43377) and Fermi/GBM (Fermi GBM team, GCN 43370;
Palafox et al., GCN 43384) detected burst GRB 260111A, collecting 2.8
ks of Photon Counting (PC) mode data between T0+94.3 ks and T0+104.8
ks.
One uncatalogued X-ray source has been detected within the estimated
3-sigma Swift/BAT error region (493 arcsec), it is below the RASS limit
and shows no definitive signs of fading. A source consistent with the
position of XRT source 2 has been reported in the optical with
COLIBRÍ, suggesting it could be the GRB afterglow (Ducoin et al., GCN
43386).
Details of this source are given below:
Source 2:
RA (J2000.0): 229.5858 = 15h 18m 20.60s
Dec (J2000.0): +51.9736 = +51d 58' 24.8"
Error: 6.3 arcsec (radius, 90% conf.)
Count-rate: (5.6 [+2.4, -1.9])e-3 ct s^-1
Distance: 27 arcsec from Swift/BAT position.
Flux: (1.56 [+0.66, -0.53])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
A catalogued source was also detected within the estimated 3-sigma
Swift/BAT error region (493 arcsec).
The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021897.
This circular is an official product of the Swift-XRT team.