[vsnet-grb-info 4735] Swift/UVOT refined analysis of GRB070531

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  6481
SUBJECT: Swift/UVOT refined analysis of GRB070531
DATE:    07/05/31 20:28:55 GMT
FROM:    Massimiliano de Pasquale at MSSL-UCL  <mdp at mssl.ucl.ac.uk>

   M. De Pasquale (MSSL/UCL) and C. B. Markwardt (GSFC/UMD)
report, on the behalf of Swift UVOT team:

   The Swift Ultraviolet/Optical telescope (UVOT) began
its White filter finding chart exposure of GRB070531
(Markwardt et al., GCN circ. 6475) 135 seconds after
the trigger. No optical afterglow is detected inside
the refined XRT error circle (Page et al., GCN circ.
6477), in the initial V and White filter exposures and
the summed exposures in all filters.

   In the following table, we report the 3 sigma
upper limits for any optical afterglow .


   Filter      Time (s)    Exp(s)     3sigma UL Mag

   White       132-231      98           19.5

   White       132-966     207           19.9


    V          238-637     393           19.2

    V          238-1111    524           19.3


    B          716-726      10           18.2

    U          692-4845     76           18.9

   UW1         668-4803    236           19.2

   UM2         643-4598    236           19.5

   UW2         745-764      20           17.8


   No correction has been made for the Galactic
reddening toward the burst, E(B-V)=0.38