TITLE: GCN CIRCULAR NUMBER: 28782 SUBJECT: GRB 201024A: 1.3m DFOT optical observations DATE: 20/10/26 20:10:16 GMT FROM: Rahul Gupta at ARIES, India Rahul Gupta (ARIES), Amit Kumar (ARIES), Dimple (ARIES), Ankur Ghosh (ARIES), Amar Aryan (ARIES), Shashi B. Pandey (ARIES), and Kuntal Misra (ARIES) report: We observed the optical afterglow ( Lipunov et al., GCN 28760; Marshall et al., GCN 28761; Fernandez-Garcia et al., GCN 28763; de Ugarte Postigo et al., GCN 28764; Jelinek et al., GCN 28766; and Kuin et al., GCN 28774 ) of Swift triggered GRB 201024A (Marshall et al., GCN 28761) using the 1.3m Devasthal Fast Optical Telescope (DFOT) at Devasthal observatory of Aryabhatta Research Institute of Observational Sciences (ARIES), India. The observations were started on 2020-10-24 at 21:03:09 UT . Multiple frames having an exposure time of 120 s were taken in R and I filters. We clearly detected the optical counterpart in the stacked images. The preliminary photometric estimate of the afterglow in the stacked images is the following : Date Start_UT T_start-T0 (hrs) Filter Exp time (s) Magnitude Mag_err ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------------------------ 2020-10-24 21:03:09 18.24 I 30*120 20.12 0.07 ------------------------------ ------------------------------ ------------------------------ ------------------------------ ------------------------------------------------ The magnitude is not corrected for the Galactic and Host extinction in the direction of the burst. Photometric calibration is performed using the standard stars from the USNO-B1.0 catalog. This circular may be cited.