TITLE:   GCN CIRCULAR
NUMBER:  10892
SUBJECT: GRB 100625A: Swift/UVOT Upper Limits
DATE:    10/06/26 17:38:46 GMT
FROM:    Wayne Landsman at GSFC/SSAI  <wayne.b.landsman@nasa.gov>

W. Landsman (NASA/GSFC/Adnet) and S. Holland ((CRESST/USRA/GSFC) report 
on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 100625A 
56s after the BAT trigger (Holland et al., GCN Circ. 10884). No optical 
afterglow consistent with the enhanced  XRT position (Page et al., GCN 
Circ. 10888) or the Gemini-South candidate afterglow position (Levan et 
al. GCN Circ. 10887) is detected in the initial UVOT exposures. 
Preliminary 3-sigma upper limits using the UVOT photometric system 
(Poole et al. 2008, MNRAS, 383, 627) for the first finding chart (FC) 
and subsequent exposures are:


Filter   T_start(s)  T_stop(s)  Exp(s)   Mag
-----------------------------------------------
white     87          206        147 >21.2 (FC)
u        269          519        246 >20.2 (FC)

white     87        11552        785 >22.6
v        598         5951        412 >20.3
b        524        10640       1117 >21.9
u        269         6522        614 >20.5
w1      4725         6362        393 >20.6
m2      4520         6157        393 >20.5
w2      4111        12302       1125 >21.5


The values quoted above are not corrected for the Galactic extinction 
due to the reddening of E(B-V) = 0.012 in the direction of the burst 
(Schlegel et al. 1998).