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GCN Circular 32218

Subject
GRB 220618A: Swift/UVOT Upper Limits
Date
2022-06-18T15:40:50Z (2 years ago)
From
Paul Kuin at MSSL <npkuin@gmail.com>
N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 220618A
151 s after the BAT trigger (Troja et al., GCN Circ. 32214).
No optical afterglow consistent with the XRT position (Troja et al. GCN
Circ. 32214) 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           151          301          147         >19.8
u_FC               309          559          246         >18.9
white              151          609          167         >19.8
v                  641          649            8         >17.4
b                  565          585           19         >17.9
u                  309          559          246         >18.9
w2                 617          637           19         >18.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.391 in the direction of the burst
(Schlegel et al. 1998).
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