TITLE:   GCN CIRCULAR
NUMBER:  24754
SUBJECT: GRB 190604B: Kitab observatory optical upper limit
DATE:    19/06/05 19:24:37 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Novichonok (KIAM), A. Pozanenko (IKI), E. Mazaeva 
(IKI), A. Volnova (IKI), I. Molotov (KIAM), Sh. Ehgamberdiev (UBAI) 
report on behalf of larger IKI GRB FuN collaboration:

We observed the field of the Swift GRB 190604B (Page et al., GCN  24742) 
  with RC-36 0.36-m telescope of Kitab Observatory starting on June 04 
(UT) 22:26:32 in  Clear filter.    We do not find any optical source 
within  enhanced Swift-XRT position (Evans  et al., GCN  24746). The 
non-detection is consistent with BOOTES-3 results (Hu et al., GCN  24750).

Preliminary photometry of the field is following.

Date       UT start   t-T0       Filter Exp.   OT  Err.   UL(3sigma)
                       (mid, days)        (s)

2019-06-04 22:26:32   0.32068    CR     21*60  n/d  n/d   18.6

The photometry is based on the nearby USNO-B1 (R2) stars.