TITLE:   GCN CIRCULAR
NUMBER:  44653
SUBJECT: GRB 260516D: FRAM-ORM optical limit
DATE:    26/05/16 23:59:09 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov <martin.jelinek@asu.cas.cz>

Martin Jelinek, Filip Novotny and Jan Strobl (ASU CAS Ondrejov, CZ),
Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek, Jan Ebr, 
Ronan Cunniffe, Petr Travnicek and Michael Prouza
(Institute of Physics, Prague, CZ)

report:

The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted
robotically to the SVOM/ECLAIRs alert of GRB 260516D (Brunet et al.,
GCNC 44649), obtaining a series of unfiltered 60s images starting at
20:54:16 UT, i.e. ~948s post trigger.

We do not detect any new or strongly variable source in comparison
to the ATLAS REFCAT2 catalog. In single images the detection limit
gradually improved from R_C > 17.1 in the first frame (midtime ~978s 
post trigger), stabilizing at R_C > ~18.3–18.4 around ~2000s post
trigger and remaining there for the rest of the ~one hour sequence.
Combining images in groups of 10 (10x60s), we reach limits of R_C >
~20 (R_C > ~19.3 for the first combined frame).