[vsnet-grb-info 6835] Swift UVOT observations of GRB081028

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8430
SUBJECT: Swift UVOT observations of GRB081028
DATE:    08/10/28 12:41:00 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps at mssl.ucl.ac.uk>

P. Schady (MSSL-UCL) and C. Guidorzi (INAF-OAB) report on behalf of  
the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 081028  
201s after the BAT detection (Guidorziet al., GCN Circ. 8421). No  
source is detected in any of the individual or coadded exposures in  
any of the UVOT filters at the XRT position (GCN Circ. 8427), or at  
the position of the reported optical counterpart (GCN Circ. 8424, GCN  
Circ. 8425).  The 3 sigma upper limits at the position of the optical  
counterpart for the first white finding chart (fc) and in consequent  
co-added observations are reported below (where T_start and T_stop  
represent the elapsed time since the BAT trigger in seconds).

Filter  T_start(s) T_stop(s)  Exp(s)   3 sigma Upper Limit
white     201           350           146         > 20.95
white     481           846            58           > 20.05
v             357          722            58           > 18.50
b             456          821            58           > 19.33
u             432          796            58           > 18.98
uvw1      407         771             58           >19.01
uvm2      382         746             58           >18.70
uvw2      506          868            55           >19.01

The above magnitudes are not corrected for the Galactic extinction  
corresponding to a reddening of E(B-V) = 0.03 mag (Schlegel et al.,  
1998, ApJS, 500, 525).  The photometry is on the UVOT photometric  
system described in Poole et al. (2008, MNRAS, 383,627).