GCN Circular 33471
Subject
GRB 230307A: Swift/UVOT detection
Event
Date
2023-03-13T15:54:52Z (3 years ago)
From
Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>
A. A. Breeveld (UCL-MSSL), and C. Salvaggio (INAF-OAB) report on behalf
of the Swift/UVOT team:
The Swift/UVOT began observations of the field of GRB 230307A 99.5 ks
after the Fermi/GBM-detected trigger (Dalessi et al., GCN 33407).
A fading source consistent with the enhanced XRT position (Burrows et
al., GCN 33465) and consistent with the optical counterpart reported by
Levan et al. (GCN 33439), Lipunov et al. (GCN 33441), Fulton et al. (GCN
33443), O'Connor et al. (GCN 33447), Im et al. (GCN 33449), Vanderspek
et al. (GCN 33453) and Bom et al. (GCN 33459) is detected in the initial
UVOT exposures. Detections and 3 sigma upper limits are given in the
following table:
Filter T_start(s) T_stop(s) Exp(s) Mag
white 99525 110441 2265 21.28 +/- 0.16
white 133031 208070 2931 22.09 +/- 0.32
white 212899 420530 3418 >22.25
u 83621 88252 422 >20.44
The magnitudes in the table are not corrected for the Galactic
extinction due to the reddening of E(B-V) = 0.084 in the direction of
the burst (Schlegel et al. 1998).