GCN Circular 34008
Subject
GRB 230618A: Swift/UVOT Upper Limits
Event
Date
2023-06-18T17:05:34Z (2 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N.P.M. Kuin (MSSL/UCL) and K. L. Page (U. Leicester)
report on behalf of the Swift/UVOT team:
The Swift/UVOT began settled observations of the field of GRB 230618A
137 s after the BAT trigger (Page et al., GCN Circ. 33989).
No optical afterglow consistent with the XRT position (Evans GCN
Circ. 33990) is detected in the initial UVOT exposures. The source
was however detected in r and i (Strausbaugh et al, GCN Circ. 33992 and KAIT
(Zhang and Filipenko, GCN Cric. 34001) in clear (R).
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 137 287 147 >20.4
u_FC 296 546 246 >19.9
white 137 1022 295 >20.7
u 296 546 246 >19.9
w1 5114 5178 63 >18.9
m2 4909 5108 197 >19.7
The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.025 in the direction of the burst
(Schlegel et al. 1998).