GCN Circular 22805
Subject
GRB 180620A: Swift/UVOT Detection
Event
Date
2018-06-20T14:19:58Z (8 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and P. A. Evans (U. Leicester) report on
behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 180620A
270 s after the BAT trigger (Evans et al., GCN Circ. 22798).
A fading source consistent with the XRT position (Osborne et al. GCN
Circ. 22802), and also detected by Butler et al. (GCN Circ. 22799),
Elenin et al. (GCN Circ. 22800), Tyurina et al. (GCN Circ. 22801) and
Guidorzi et al. (GCN Circ. 22803), is detected in the initial UVOT
exposures. The detection in the UVOT uvw2 filter implies a redshift
limit of 1.2.
The preliminary UVOT position is:
RA (J2000) = 18:39:35.09 = 279.89619 (deg.)
Dec (J2000) = +23:14:39.1 = 23.24419 (deg.)
with an estimated uncertainty of 0.43 arc sec. (radius, 90% confidence).
Preliminary detections 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 270 420 147 17.68 �� 0.04
v 427 1420 117 18.43 �� 0.19
b 525 717 39 18.77 �� 0.20
u 500 692 39 17.92 �� 0.17
w1 476 2158 194 18.86 �� 0.20
m2 623 7111 391 19.65 �� 0.27
w2 574 8136 588 20.00 �� 0.23
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.13 in the direction of the
burst (Schlegel et al. 1998).