[vsnet-grb-info 21338] GRB 181123B: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23437
SUBJECT: GRB 181123B: Swift/UVOT Upper Limits
DATE:    18/11/23 15:38:28 GMT
FROM:    Samantha Oates at MSSL  <sro at mssl.ucl.ac.uk>

GRB 181123B: Swift/UVOT Upper Limits

S. R. Oates (U.Warwick) and A. Y. Lien (GSFC/UMBC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 181123B
84 s after the BAT trigger (Lien et al., GCN Circ. 23432).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 23434)
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            84          233          147         >20.3
u_FC               296          546          246         >19.5
white               84         6529          727         >21.0
v                  626        10922         1228         >19.8
b                  551         6324          432         >20.1
u                  296         6119          659         >20.1
w1                4278        12566         1113         >20.2
m2                5509        11827         1082         >20.5
w2                5100         6734          393         >19.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.03 in the direction of the burst
(Schlegel et al. 1998).