TITLE:   GCN CIRCULAR
NUMBER:  35605
SUBJECT: GRB 240123A: Mondy optical afterglow observations
DATE:    24/01/23 15:52:15 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI),  A. Pozanenko (IKI), E. Klunko (ISTP), S. Belkin (IKI) report on behalf of GRB IKI FuN:

We observed the field of GRB 231117A (D'Ai et al., GCN 35602) with AZT-33IK telescope of Mondy observatory  in  R-filter starting on 2024-01-23 (UT) 14:00:48.  We clearly detect a new fading object at coordinates (J2000) 13 17 23.87 +60 37 05.3 with uncertainties  of  0.2 arcsec which is slightly differ from coordinates reported by UVOT (D'Ai et al., GCN 35602). The object is absent in SDSS catalogue. Preliminary photometry is following

Date       UT start  t-T0     Exp.   Filter   OT     Err.
                   (mid, days)  (s)
2024-01-23 14:00:48  0.126415  7x120 R        19.07  0.10 20.9
2024-01-23 14:20:48  0.144479 13x120 R        19.25  0.10 21.3  
2024-01-23 14:46:49  0.163934 15x120 R        19.37  0.11 21.3  

The photometry is based on nearby USNO-B1.0 R2 stars.