GCN Circular 28507
Subject
GRB 200925B: Swift/UVOT Detection
Event
Date
2020-09-26T20:14:25Z (5 years ago)
From
Samantha Oates at MSSL <samantha.oates@alumni.ucl.ac.uk>
S. R. Oates (U.Birmingham) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200925B
82 s after the BAT trigger (Cenko et al., GCN Circ. 28499).
A source consistent with the XRT position (Beardmore et al. GCN Circ. 28503)
and the optical position reported by the OSN
(de Ugarte Postigo et al., GCN Circ. 28501) and MASTER
(Lipunov et al., GCN Circ. 28502) 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 (FC) 82 232 147 19.80 +/- 0.20
white 574 1714 264 20.77 +/- 0.37
v 623 1763 136 >18.9
b 549 1689 117 >19.6
u (FC) 294 544 246 >19.7
u 294 1663 343 >19.9
w1 672 1813 136 >19.0
m2 1249 1441 39 >17.7
w2 599 1739 117 >18.9
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).