GCN Circular 20914
Subject
GRB 170318A: Swift/UVOT Upper Limits
Event
Date
2017-03-18T21:27:48Z (9 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL) and B. Sbarufatti (INAF-OAB/PSU)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 170318A
117 s after the BAT trigger (Sbarufatti et al., GCN Circ. 20904).
No optical afterglow consistent with the XRT position (Evans et al. GCN
Circ. 20907) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:
Filter T_start(s) T_stop(s) Exp(s) Mag
white_FC 117 266 147 >20.4
u_FC 329 552 220 >19.6
white 117 6605 363 >20.8
v 2222 2241 19 >17.0
b 2147 6400 216 >19.8
u 329 6195 417 >20.1
w1 5790 5990 197 >19.4
m2 5585 5784 197 >19.3
w2 2197 11766 560 >20.4
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.97 in the direction of the
burst (Schlegel et al. 1998).