GCN Circular 22898

S.W.K. Emery (UCL-MSSL) and E. Sonbas (Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 180703A
17269 s after the Fermi/LAT trigger (Racusin et al. GCN Circ. 22883
Not found
 
 
).
No optical afterglow consistent with the XRT position of the
uncatalogued X-ray source, source 1 (Gibson et al. GCN Circ. 22891
Not found
 
 
)
or the position from LCO Sutherland (Guidorzi et al. GCN Circ. 22892
Not found
 
 
)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
exposures at the position of source 1 are:

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

b             17353         28862           47         >19.2
u             17323         28834          116         >19.5
uvw1          17269         28807          234         >19.8
uvw2          17384         28917           97         >19.2

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.02 in the direction of the burst
(Schlegel et al. 1998).