GCN Circular 17909

L. M. Z. Hagen (PSU) and V. D'Elia (ASDC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 150607A
137 s after the BAT trigger (D'Elia et al., GCN Circ. 17904
Not found
 
 
). A source
consistent with the XRT position (Osborne et al. GCN Circ. 17905
Not found
 
 
) is
detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  09:19:57.20 = 139.98833 (deg.)
    Dec (J2000) = +68:26:10.3  =  68.43619 (deg.)
with an estimated uncertainty of 0.44 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early
exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white              137          286          146         18.10 +/- 0.07
white              628         1204          205         20.04 +/- 0.31
white             1358         7668          412        >20.55
v                  118          128            9         16.71 +/- 0.35
v                  678         7955          446        >19.02
b                  604         7463          367        >19.65
u                  348          598          245         18.88 +/- 0.27
u                  753         7258          352        >19.37
uvw1               728         7053          352        >19.60
uvm2              1084         6848          313        >19.74
uvw2               654         7874          568        >20.30

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.07 in the direction of the burst
(Schlegel et al. 1998).