GCN Circular 19656

L. M. Z. Hagen (PSU) and S. B. Cenko (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 160703A
75 s after the BAT trigger (Cenko et al., GCN Circ. 19645
Not found
 
 
). We detect a
fading source consistent with the XRT position (D'Elia et al. GCN Circ.
19655
Not found
 
 
) and optical detections (Tachibana et al., GCN Circ. 19652
Not found
 
 
; Kuroda
et al., GCN Circ. 19653
Not found
 
 
).

Preliminary detections 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               75          225          147         14.09+-0.02
white              567         1014          186         16.64+-0.03
white             4890         5090          196         18.33+-0.05
v                  617         1064           58         16.51+-0.10
v                 5300         5500          196         18.34+-0.17
b                  543          735           38         16.38+-0.06
b                 4685         4885          196         18.76+-0.11
u                  288          537          245         15.05+-0.03
u                  691          710           19         15.88+-0.09
u                 4480         4680          196         17.79+-0.08
uvw1               666         1113           58         16.80+-0.12
uvm2               642         1089           58         17.75+-0.25
uvm2              5505         5695          187         19.07+-0.29
uvw2               593         1040           58         18.38+-0.27
uvw2              5096         5295          196         19.45+-0.30

The detection in all UVOT filters is consistent with a redshift of
z < ~1.5.

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.15 in the direction of the burst
(Schlegel et al. 1998).