[vsnet-grb-info 20981] GRB 180805A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  23079
SUBJECT: GRB 180805A: Swift/UVOT Upper Limits
DATE:    18/08/05 22:12:30 GMT
FROM:    Paul Kuin at MSSL  <npkuin at gmail.com>

Paul Kuin (MSSL/UCL) and P. D'Avanzo (INAF-OAB)

report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180805A
90 s after the BAT trigger (D'Avanzo et al., GCN Circ. 23074).
No optical afterglow consistent with the XRT position (Beardmore et
al. GCN Circ. 23075)  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            90          239          147         >19.8
u_FC               302          552          246         >19.5
white               90         1029          334         >20.6
v                  632         1080           58         >18.0
b                  558         1172           52         >19.1
u                  302         1153          285         >19.6
w1                 681         1129           58         >19.3
m2                 656         1104           39         >19.4
w2                 608         1055           58         >18.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.19 in the direction of the burst
(Schlegel et al. 1998).