TITLE:   GCN CIRCULAR
NUMBER:  8277
SUBJECT: GRB 080919: Swift/UVOT Refined Analysis
DATE:    08/09/19 18:17:38 GMT
FROM:    Stefan Immler at NASA/GSFC  <stefan.m.immler@nasa.gov>

S. Immler (CRESST/GSFC/UMD) and S. T. Holland (CRESST/USRA/GSFC), on 
behalf of the Swift Team:

Swift UVOT started observing GRB 080919 (Preger et al. GCN 8270) 82 
seconds after the BAT trigger. The source detected by REM (Covino et al. 
GCN 8271) is detected in all optical and in the uvw1 filter and shows no 
signs of fading over a period of ~25 ks after the trigger. It is the 
only optical source detected within the XRT error circle (Preger et al. 
GCN 8276). The following UVOT magnitudes (and 3-sigma upper limits) are 
measured:

Filter   T_start   T_stop   Exp(s)  Mag (3-sigma upper limit)
-----------------------------------------------------
white      82    18561   2,203   18.4±0.1
v         188    23441   2,766   17.2±0.1
b         670    17648   1,375   18.3±0.1
u         645     7509    510   19.6±0.3
uvw1      620    25158   1,301   20.4±0.5
uvm2      594    24347   1,278    >20.4
uvw2      701    19375   1,809    >20.8

The quoted upper limits have not been corrected for the expected 
Galactic extinction along the line of sight of E(B-V) of 0.49 mag 
(Schlegel et al. 1998). All photometry is on the UVOT flight system 
described in Poole et al. (2008, MNRAS, 383, 627).