GCN Circular 40471
Subject
GRB 250516A: Swift/UVOT Detection
Event
Date
2025-05-16T22:17:55Z (2 months ago)
From
Sam Shilling at Lancaster University <shilling.sam@gmail.com>
Via
Web form
S. P. R. Shilling (Lancaster U.) and A. P. Beardmore (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 250516A
108 s after the BAT trigger (Beardmore et al., GCN Circ. 40467). A source
consistent with the enhanced XRT position (Evans et al., GCN Circ. 40468)
is detected in the initial UVOT exposures.
The preliminary detection 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 108 1715 411 20.5 +/- 0.3
v 650 1765 136 >18.5
b 576 1691 117 >19.2
u 320 1838 362 >19.7
w1 699 1814 117 >18.8
w2 626 1741 97 >19.1
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.062 in the direction of the burst
(Schlegel et al. 1998).