GCN Circular 43105
Subject
GRB 251214B: Swift/UVOT Detection
Event
Date
2025-12-15T05:01:50Z (2 days ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
Via
email
N.P.M. Kuin (MSSL/UCL) and R. Eyles-Ferris (U. Leicester) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 251214B 64 s
after the BAT trigger (Eyles-Ferris et al., GCN Circ. 43089). A source
consistent with the XRT position Evans et al. GCN Circ. 43098) is detected
in the initial UVOT exposures.
There were early reports of the optical afterglow from Zhe Kang et al. (GCN
Circ. 43093) and S.Y. Fu et al. (GCN Circ. 43097).
The preliminary UVOT position is:
RA (J2000) = 22:00:50.53 = 330.21053 (deg.)
Dec (J2000) = -09:09:46.4 = -9.16290 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
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 64 214 147 17.21 +/- 0.03
v 606 800 39 17.09 +/- 0.17
b 532 724 39 18.08 +/- 0.17
u 277 527 246 17.76 +/- 0.08
w1 655 1472 97 >18.9
m2 630 1447 97 >20.3
w2 582 5213 136 >19.6
The magnitudes in the table are not corrected for the Galactic extinction due
to the reddening of E(B-V) = 0.039 in the direction of the burst (Schlegel
et al. 1998).