GCN Circular 28743
Subject
GRB 201020B: Swift/UVOT Detection
Event
Date
2020-10-22T12:34:19Z (5 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 201020B 72102 s after the Fermi
GMB/LAT trigger (Fermi GBM team, GCN Circ. 28702; Malacaria and Meegan, GCN Circ. 28710; Arimoto et
al., GCN Circ. 28716).
A source consistent with the Master position (Lipunov et al., GCN Circ. 28718), also detected by Xu
et al., (GCN Circ. 28719), Ridnaia et al. (GCN Circ. 28723), Belkin et al. (GCN Circ. 28723) and
Sbarufatti et al. (GCN Circ. 28740), is detected in the initial UVOT exposures. We note there is a
faint USNO-B1.0 source (1670-0037526, Bmag ~21.7) 5.2" away from this position.
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 73636 73973 332 19.54 �� 0.09
v 73979 74316 331 19.30 �� 0.28
u 72102 72821 708 19.12 �� 0.11
u 73293 73631 332 19.41 �� 0.19
The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.15 in the direction of the burst (Schlegel et al. 1998).