GCN Circular 40606
Subject
GRB 250601A: Swift/XRT candidate afterglow
Date
2025-06-02T15:13:44Z (4 days ago)
From
Chiara Salvaggio at INAF OABrera <chiara.salvaggio@inaf.it>
Via
email
C. Salvaggio (INAF-OAB), S. B. Cenko (GSFC), B. Sbarufatti (INAF-OAB)
report on behalf of the Swift-XRT team:
Swift-XRT has performed follow-up observations of the Fermi/GBM,
Swift/BAT-GUANO detected burst GRB 250601A (GCN 40596, 40600).
Two XRT sources have been previously reported in GCN 40604. One of the two
sources (source 2) has an eROSITA counterpart, while XRT source 3 is a new
transient. Therefore we consider source 3 a candidate afterglow for GRB
250601A.
Source 3:
RA (J2000.0): 90.0936 = 06:00:22.47
Dec (J2000.0): -57.2778 = -57:16:40.0
Error: 5.7 arcsec (radius, 90% conf.)
Count-rate: (3.6 [+1.6, -1.3])e-3 ct s^-1
Distance: 60 arcsec from Swift/BAT position.
Flux: (1.00 [+0.45, -0.35])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)
More Swift/XRT observations are planned to (un)confirm the afterglow
detection.
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/00021844.
This circular is an official product of the Swift-XRT team.