GCN Circular 45593
Subject
GRB 260909A: Swift-XRT observations
Event
Date
2026-09-16T11:20:41Z (2 days ago)
From
Phil Evans at U of Leicester <pae9@star.le.ac.uk>
Via
email
S. Dichiara (PSU), M. Capalbi (INAF-OAR), M. Perri (SSDC & INAF-OAR),
V. D'Elia (SSDC & INAF-OAR), J.A. Kennea (PSU), D.N. Burrows (PSU),
K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester) and P.A. Evans
(U. Leicester) reports on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the
SVOM/ECLAIRs-detected burst GRB 260909A, collecting 2.9 ks of Photon
Counting (PC) mode data between T0+137.7 ks and T0+264.7 ks.
No X-ray sources have been detected within the estimated 90% SVOM/MXT
error region (64 arcsec; Saccardi et al. GCN 45534) or at the position
of the EP candidate (Mao et al. GCN 45543). The 3-sigma upper limit in
the field ranges from ~0.003 to ~0.005 ct s^-1, corresponding to a
0.3-10 keV observed flux of 1.1e-13 to 1.8e-13 erg cm^-2 s^-1 (assuming
a typical GRB spectrum).
Four uncatalogued sources were detected too far from the GRB position
to be likely afterglow candidates.
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/00021911.
This circular is an official product of the Swift-XRT team.