GCN Circular 26693
Subject
GRB 200107B: Swift/UVOT Observations
Event
Date
2020-01-09T22:28:12Z (6 years ago)
From
Frank Marshall at Swift/UVOT <marshall@milkyway.gsfc.nasa.gov>
F.E. Marshall (NASA/GSFC) and M. G. Bernardini (INAF-OAB)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 200107B
903 s after the BAT trigger (Bernardini et al., GCN Circ. 26661).
Some of the exposures are affected by poor attitude control,
but we have selected observing times for which this is not
a significant issue. A source consistent with the position of the optical
source reported by Lipunov (GCN Circ. 26660) is weakly detected (2.6 sigma)
in the initial UVOT exposure.
The preliminary detection 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 903 1052 55 19.3 (+0.5/-0.4)
v 1059 1079 19 >18.6
b 1157 1177 19 >18.6
u 1133 3144 179 >19.7
w1 2777 2976 197 >19.5
w2 1208 1228 19 >18.2
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst
(Schlegel et al. 1998).