GCN Circular 6473

M. De Pasquale (MSSL/UCL) and S. T. Holland (CRESST/USRA/GSFC)
report, on the behalf of Swift UVOT team:

  The Swift Ultraviolet/Optical telescope (UVOT) began its
initial V-band finding chart exposure of GRB070529 (Holland et al.,
GCN circ. 6466
Not found
 
 
) 134 seconds after the trigger and the optical
afterglow is clearly detected inside the refined XRT error
circle (Mangano et al., GCN circ. 6469
Not found
 
 
). Successively, the
optical source appears to fade with a decay slope, based
on the V band datapoints, of about -1.8.

  In the following table, we report the magnitudes and 3 sigma
upper limits for this source. Errors are at 1 sigma level.


  Filter      Time (s)    Exp(s)        Mag

   V          134-534      393      17.1 +/- 0.1

   V          652-1253     420      19.3 +/- 0.4

   V        40339-47072   2039         > 20.4


   B          613-758      20          > 18.8

   U          588-6277    439          > 20.1

  UW1         564-7038    459          > 20.5

  UM2         540-7038    592          > 20.8

  UW2         628-6687    432          > 21.0


  No observation was performed in the white filter,
due to the crowded field.

  No correction has been made for the considerable
Galactic reddening toward the burst, E(B-V)=0.3
(Schlegel et al. 1998).