TITLE:   GCN CIRCULAR
NUMBER:  8469
SUBJECT: GRB 081102:  Swift/UVOT refined analysis
DATE:    08/11/03 15:13:14 GMT
FROM:    Stefan Immler at NASA/GSFC  <stefan.m.immler@nasa.gov>

S. Immler (GSFC/CRESST/UMCP) and T. N. Ukwatta (GSFC/GWU) report on the 
behalf of the Swift UVOT team:

The Swift Ultra-Violet/Optical Telescope (UVOT) began observing GRB 
081102 (trigger 333427) 83 seconds after the BAT trigger (Ukwatta et 
al., GCN Circ. 8462). No afterglow is detected at the enhanced XRT 
position (Osborne et al., GCN Circ. 8467) in the initial v-filter 
finding chart or subsequent images. The limiting magnitudes (3-sigma in 
3" radius apertures) in each of the UVOT filters are as follows:

Filter  T_start(s)  T_stop(s)  Exp(s)  Mag UL (3sig)

white      100       19051       1246     >21.9
v           83      35803       1423     >20.3
b          433      24833       1808     >21.3
u          408     30614       2717     >21.3
uvw1       383      29977       2922     >21.1
uvm2      359      36395       2701     >20.9
uvw2      309      34890       1434     >20.7

The values quoted above are in the UVOT photometric system (Poole et al. 
2008, MNRAS, 383, 627). They are not corrected for the high (and 
unreliable) Galactic extinction at the low Galactic latitude of the 
burst of <5 degrees.