GCN Circular 30832
Subject
GRB 210912A: Swift/UVOT Detection
Date
2021-09-13T07:47:54Z (3 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 210912A
60 s after the BAT trigger (Troja et al., GCN Circ. 30820).
A source consistent with the optical position
(Hu et al. GCN Circ. 30823)
is detected in the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 08:39:34.27 = 129.89280 (deg.)
Dec (J2000) = +79:13:17.1 = 79.22141 (deg.)
with an estimated uncertainty of 0.47 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 60 209 147 18.73 +/- 0.08
v 602 621 19 >17.8
b 528 547 19 >18.3
u 272 490 214 19.56 +/- 0.31
w2 577 597 19 >18.8
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).