TITLE:   GCN CIRCULAR
NUMBER:  26070
SUBJECT: GRB 191024A: Swift/UVOT Upper Limits
DATE:    19/10/24 16:21:03 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) 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 191024A 833 s after the BAT trigger
(Page et al., GCN Circ. 26063).
No optical afterglow consistent with the XRT position (Beardmore et al., GCN Circ. 26064) 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           833          982          147         >21.2
white              833        13531          360         >22.0
v                  989         6893          274         >19.9
b                 1087        13389         1043         >21.6
u                 1062        19531          716         >21.3
w1                1038        19072         1160         >21.1
m2                6898         7098          197         >20.2
w2                1137         1506           39         >19.7

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of
E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).