GRB 241026A: SAO RAS optical observations

We observed the field of GRB 241026A (The Fermi GBM team, GCN 37894; Melandri et al., GCN 37896, Li et al., GCN 37909; Zhang et al., GCN 37921; Zhang, Xiong and Wang GCN 37924; Pal et al., GCN 37929) with the 1-m telescope of SAO RAS, Zeiss-1000/CCD-photometer in Rc band on October 28/29 and 29/30 nights. The OT (Moskvitin et al., GCNs 37899, 37916; Watson et al., GCN 37900; Zheng & Filippenko GCN 37903; Shrestha et al., GCN 37913; Mo et al., GCN 37915; Mohan et al., GCN 37918; Izzo et al., GCN 37925; Wang et al., GCN 37928) is not detected in the October 28/29 data, but marginally detected in the October 29 stacked frame. Preliminary results are as follows. date UT_start--UT_end t_mid-T0 exp, s R magnitude R_lim 28/29 21:30:53--01:10:41 2.02657 500 n/d 21.6 29 17:42:02--18:36:46 2.81034 2490 22.95 +/- 0.24 23.3 The frames were calibrated against nearby USNO-B1 stars (R2 magnitudes) and not corrected for MW extinction.