TITLE:   GCN CIRCULAR
NUMBER:  23596
SUBJECT: GRB 181228A: Mondy and AbAO optical upper limits
DATE:    18/12/31 17:37:10 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), R. Ya. Inasaridze 
(AbAO),  E. Mazaeva (IKI),   A. Volnova (IKI), V. R. Ayvazian (AbAO), 
G. V.  Kapanadze (AbAO)   report   on behalf of the IKI GRB-FuN:

We observed the field of GRB 181228A (Moss et al., GCN 23570; Beardmore 
et al., GCN 23574) with AZT-33IK telescope of Sayan observatory (Mondy) 
   starting on Dec. 28 (UT) 13:48:11 in I-filter, and AS-32 telescope of 
Abastumani Observatory (AbAO) on Dec. 28 (UT) 15:13:46 in R-filter. We 
do not detected    the afterglow (D'Avanzo et al., GCN 23575; Lipunov et 
al. GCN 23576; Xu et al., GCN 23593).

Preliminary photometry of the field  is following.

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

2018-12-28 13:48:11 0.47494 I      30*120 n/d  n/d   23.8
2018-12-28 15:13:46 0.54879 R      63*60  n/d  n/d   21.0


The photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id R2    I2
1032-0046066 16.66 16.08
1031-0043284 16.04 15.36