GCN Circular 21220

S.W.K. Emery (UCL-MSSL) and A. D'Ai (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 170607A
84 s after the BAT trigger (D'Ai et al., GCN Circ. 21214
Not found
 
 
).
GRB 170607A was also triggered by Fermi GBM
(Hamburg and Meegan GCN Circ. 21218
Not found
 
 
)
We detect a fading afterglow consistent with the position given by XRT
(Beardmore et al., GCN Circ. 21215
Not found
 
 
) and ground-based optical detections
(Heintz et al., GCN Circ. 21217
Not found
 
 
; Lipunov et al., GCN Circ. 21219
Not found
 
 
).

The preliminary UVOT position is:
    RA  (J2000) =  00:29:27.82 =   7.36591 (deg.)
    Dec (J2000) = +09:14:36.0  =   9.24334 (deg.)
with an estimated uncertainty of 0.42 arc sec. (radius, 90% confidence).

Preliminary detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

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

white_FC            84          233          147         15.76 +/- 0.02
white              575         5285          461         17.11 +/- 0.03
white             6895         7065          197         17.50 +/- 0.04
v                  625         5696          313         17.51 +/- 0.11
b                  551         1859          132         17.63 +/- 0.09
u_FC               295          545          246         16.14 +/- 0.04
u                  699         6205          210         16.80 +/- 0.06
u                 6454        29372         1601         17.68 +/- 0.04
uvw1               847         6105          313         16.87 +/- 0.06
uvm2              5700         5900          197         16.86 +/- 0.09
uvw2              1720         5491          216         17.04 +/- 0.07


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).