TITLE:   GCN CIRCULAR
NUMBER:  37363
SUBJECT: GRB 240828B: AbAO optical upper limit
DATE:    24/08/31 16:13:21 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <grb.alex@gmail.com>

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

We observed the field of GRB 240828B (Le Provost, GCN 37318; Page et al.,
GCN 37334) with the 70-cm AS-32 telescope of Abastumani Observatory (AbAO)
in the R-filter, starting on 2024-08-29 at 23:38:46 (UT). We did not detect
the optical counterpart in the stacked image within the Swift-XRT error
circle (Page et al., GCN 37334; ). Preliminary photometry is as follows:

Date UT_start t-T0 Filter Exp. OT err UL(3σ)
(mid, days) (s)
2024-08-29 23:38:46 1.46045 R 74×60 n/d n/d 22.0

The magnitudes were calibrated using nearby USNO-B1.0 stars.
RA DEC R2
04:13:38.682 +16:40:58.242 17.00
04:13:51.313 +16:42:50.073 16.7