TITLE:   GCN CIRCULAR
NUMBER:  21953
SUBJECT: GRB171001A: D50 optical limit
DATE:    17/10/01 22:50:08 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek, Jan Strobl and Rene Hudec (ASU CAS Ondrejov)

We observed the field of the Swift GRB171001A (trigger #775553, Lien et al.
GCNC 21946) with the 0.5m telescope of Ondrejov observatory, the obseration
started at 21:17UT, i.e. about 2.9h after trigger and lasted for 30 miutes,
when the field became observable. On a series of unfiltered exposures we do
not detect any new object within or in the vicinity of the XRT errorbox
(Evans et al., GCNC 21952) down to the USNO-B/R2 calibrated limit  of
R>20.0.