GCN Circular 19388

U.Quadri, L.Strabla and R.Girelli report:

We imaged the field of GRB 160504A detected by SWIFT(trigger 685124)
with the robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy. Member of: 
AAVSO - American Association of Variable Star Observers.
ISSP - Italian Supernovae Search Project.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.

The observations started 22.45 min after the GRB trigger,  
with our Schmidt telescope D=320/400 mm F/D=3.1.

Weather conditions were good.

We co-added 2 series of 20 exposures of 120 sec each.

Start T0+      End T0+      Vlim
22.45 min    111.33 min     20

We did not found any optical counterpart in the error 
box of the XRTcandidate.
(D. Malesani (DARK/NBI), J. A. Kennea (PSU)et al)

Magnitudes were estimated with the UCAC4 cat. and 
are not corrected for galactic dust extinction.

Reference:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.