TITLE:   GCN CIRCULAR
NUMBER:  8406
SUBJECT: Swift UVOT observations of GRB 081024
DATE:    08/10/25 11:53:56 GMT
FROM:    Patricia Schady at MSSL/Swift  <ps@mssl.ucl.ac.uk>

M. De Pasquale (MSSL/UCL) and G. Stratta (ASDC) report on behalf of  
the Swift UVOT team.

The Swift UltraViolet/Optical Telescope (UVOT) began its finding chart  
exposure of GRB081024 (Swift BAT trigger
number 332516, Stratta et al., GCN Circ. 8398), 77s after the trigger.

We do not detect any new source at the XRT position reported in GCN  
Circ. 8403 (Beardmore et al.) either
in the finding chart nor in in successive coadded observations.

The magnitude 3 sigma upper limits for detecting GRB081024 at the XRT  
position are given below.

  Filter  Tstart(s)  Tstop(s)  Exp(s)  Magnitude
  wh        77          227        147        >20.8
  wh        516       13395     1258      >22.0
  v           565       758         39          >18.5
  v           1041     7298       490        >19.9
  b           491       856         58          >19.6
  b           1140     12771     1358      >21.4
  u           235       485         250        >20.1
  u           639       11859     807        >21.0
  uvw1     615       7615      436        >20.2
  uvm2     590       7503      529        >20.5
  uvw2     541       7093      529        >20.6


  The values quoted above are on the UVOT Photometric System (Poole et  
al, 2008, MNRAS 383,627). They are not
corrected for the unknown but expected large Galactic extinction in  
the direction of this burst.