[vsnet-grb-info 7037] GRB 081204: Swift/UVOT Upper Limits

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  8621
SUBJECT: GRB 081204: Swift/UVOT Upper Limits
DATE:    08/12/05 14:17:38 GMT
FROM:    Peter Curran at MSSL  <pac at mssl.ucl.ac.uk>

P.A. Curran (UCL-MSSL) and W. Baumgartner  (GSFC)
report on behalf of the Swift/UVOT team:


The Swift Ultra-Violet/Optical Telescope (UVOT) began settled ToO 
observations of the  INTEGRAL-IBAS localised  GRB 081204 (Gotz et al., 
GCN 8614) ~ 3 hours after the event. The field was observed with the 
white filter only. No afterglow is detected within the 7" XRT position 
(Mangano et al., GCN 8616) in the co-added image, down to the following 
3-sigma limiting magnitude:

Filter      T_start(s)    Exp(s)     Mag UL (3sig)
-----------------------------------
white      1.01e5        3.4e3      >  22.04
-----------------------------------

There is a DSS detected object approximately 11" south-west of the 
center of the XRT position with an observed white magnitide of ~20.5.

The values quoted above are in the UVOT photometric system (Poole et al. 
2008, MNRAS, 383, 627); they are not corrected for the expected Galactic 
extinction along the line of sight which corresponds to a reddening of 
E(B-V)=0.027 mag (Schlegel et al. 1998).