GCN Circular 22510
Subject
GRB 180316A: Swift/UVOT Detection
Event
Date
2018-03-16T15:48:27Z (8 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and A. Melandri (INAF-OAB) report on behalf of
the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180316A
105 s after the BAT trigger (Melandri et al., GCN Circ. 22500).
A fading source consistent with the enhanced XRT position (Evans et al.
GCN Circ. 22508) and the optical transient reported by Lipunov et al.
(GCN Circ. 22503), Shady & Steinmassl (GCN Circ. 22504) and Martone et
al. (GCN Circ. 22507), Butler et al. (GCN Circ. 22509) is detected in
the initial UVOT exposures.
The preliminary UVOT position is:
RA (J2000) = 17:41:42.87 = 265.42861 (deg.)
Dec (J2000) = +00:44:53.7 = 0.74824 (deg.)
with an estimated uncertainty of 0.42 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 finding chart (white_fc) and early exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_fc 105 254 147 16.27 �� 0.03
white 596 616 20 17.40 �� 0.11
v 646 839 39 17.15 �� 0.18
b 572 592 20 17.40 �� 0.15
u 317 566 246 16.44 �� 0.04
w1 695 22410 1175 >20.4
m2 12527 12578 50 >19.2
w2 622 6753 255 >19.5
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.28 in the direction of the
burst (Schlegel et al. 1998).