GCN Circular 30991
Subject
GRB 211025A: Swift/UVOT Detection
Event
Date
2021-10-25T14:35:00Z (4 years ago)
From
Samantha Oates at MSSL <samantha.oates@alumni.ucl.ac.uk>
S. R. Oates (U.Birmingham) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 211025A
131 s after the BAT trigger (Gropp et al., GCN Circ. 30986).
A source consistent with the XRT position (Evans et al. GCN Circ. 30987)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 10:49:31.93 = 162.38304 (deg.)
Dec (J2000) = +31:30:44.3 = 31.51231 (deg.)
with an estimated uncertainty of 0.9 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_FC 131 281 147 > 20.2
white 131 943 220 19.90 +/- 0.25
white 5965 6164 197 > 20.4
v 4940 6509 329 > 19.0
b 5760 5960 197 > 19.8
uvw1 669 688 19 > 17.5
uvw1 5350 5550 197 > 19.5
uvm2 5145 5345 197 > 19.4
uvw2 4735 6370 393 > 20.0
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.027 in the direction of the burst
(Schlegel et al. 1998).