TITLE:   GCN CIRCULAR
NUMBER:  38731
SUBJECT: GRB 241229A: SAO RAS optical observations
DATE:    24/12/30 16:54:52 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. S. Moskvitin, O. I. Spiridonova (SAO RAS), A. S. Pozanenko (IKI RAS)
report on behalf of the GRB follow-up team.

We partially covered the error circle of SVOM/ECLAIRs GRB 241229A
(Liang et al., GCN 38697) with the 1-m telescope of SAO RAS, Zeiss-1000
equipped with the CCD-photometer. We obtained 6 x 300 sec. images
in Rc band on 2024-12-29T23:40:01--2024-12-30T00:16:47
(t_mid - T0 = 23.9 hours).

Within the enhanced XRT position (Williams et al., GCN 38728)
of X-ray candidate previously reported by Evans (GCN 38711) and
Jiang et al. (GCN 38726, EP-FXT candidate #2) we did not detect any new
source down to the limiting magnitude of R_lim = 22.3.

We should note the presence of the nearby galaxy J125129.26+314455.4
visible in archive images with the brightness of R2 = 20.39 (USNO-B1)
and r = 20.402 +/- 0.043 (SDSS). In our stacked frame we measured
the brightness of the galaxy as R = 20.26 +/- 0.05 (diameter
of aperture 9".94, calibrated against R2 magnitudes of nearby USNO-B1
stars). The angular distance from EP candidate position
to the measured center of the galaxy is 2".5 (corresponding 18 kpc,
z_phot = 0.2875, H0 = 72 km/s/Mpc), and 6".7 (47 kpc)
from XRT position to the galaxy.