[vsnet-grb-info 20839] GRB 180709A: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  22937
SUBJECT: GRB 180709A: Swift/UVOT Upper Limits
DATE:    18/07/09 20:38:53 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld at ucl.ac.uk>

A. A. Breeveld (UCL-MSSL), S. W. K. Emery (UCL-MSSL) and F. E. Marshall 
(NASA/GSFC) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180709A 
115 s after the BAT trigger (Marshall et al., GCN Circ. 22930).
No optical afterglow consistent with the XRT position (Beardmore et al., 
GCN Circ. 22933) 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           115          264          147         >20.5
u_FC               273          523          246         >19.6
v                  604          797           39         >18.0
b                  529          723           39         >19.0
uvw1               654          846           39         >17.7

The magnitudes in the table are not corrected for the Galactic 
extinction due to the reddening of E(B-V) = 2.72 in the direction of the 
burst (Schlegel et al. 1998).