GCN Circular 42355
Subject
GRB 251017A: Swift/UVOT Detection
Event
Date
2025-10-18T12:06:08Z (2 days ago)
From
s.shilling@lancaster.ac.uk
Via
Web form
S. P. R. Shilling (Lancaster U.) and R. Gupta (NASA GSFC) report on behalf of the
Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251017A
98 s after the BAT trigger (Gupta et al., GCN Circ. 42322).
A source consistent with the enhanced XRT position (Goad et al., GCN Circ. 42326)
is detected in the initial UVOT exposures.
Preliminary detections and 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 121 270 147 20.09 +/- 0.22
v 98 1234 109 >18.8
b 588 5138 83 >19.6
u 333 5126 501 >20.3
w1 712 4921 255 >18.5
w2 811 1384 58 >20.4
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.108 in the direction of the burst
(Schlegel et al. 1998).