TITLE:   GCN CIRCULAR
NUMBER:  35572
SUBJECT: GRB 240118A: AbAO optical upper limit
DATE:    24/01/19 01:25:42 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI), A. Pozanenko (IKI), R. Ya. Inasaridze (AbAO), S. Belkin (IKI) report on behalf of IKI GRB FuN:

We observed the field of  Fermi LAt localization of GRB 240118A (Bissaldi, GCN 35560)  and detected also Fermi GBM (Fermi GBM team, GCN 35558; Hamburg, GCN 35563), NuSTAR (Grefenstette, GCN 35564), Swift BAT (DeLaunay, GCN 35568), and Konus-Wind (Frederiks, GCN 35567)  with AS-32 telescope of Abastumani observatory (AbAO) in R-filter starting on  2024-01-18 (UT) 16:47:55. No optical candidate is detected in the LAT localization area (Bissaldi, GCN 35560). Preliminary photometry of the filed is following

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

2024-01-18 16:47:55  0.625069  R     40*60   n/d    n/d   17.4

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