TITLE: GCN CIRCULAR NUMBER: 29591 SUBJECT: GRB 210217A: 3.6m DOT optical observations DATE: 21/03/01 07:26:44 GMT FROM: Dimple Panchal at ARIES, India Dimple (ARIES), K. Misra (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES), A. Kumar (ARIES), B. Kumar (ARIES), S.B. Pandey (ARIES) report: We carried out the follow-up observations of GRB 210217A ( Simpson et al. GCN #29521) with Aries Devasthal Faint Object Spectrograph and Camera (ADFOSC) mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal observatory of Aryabhatta Research Institute of observational sciencES (ARIES), India. We detected the optical afterglow (Simpson et al. GCNs #29521,29555; Zhu et al. GCN #29523; Zheng et al. GCN #29533; Shrestha et al. GCN #29535; Kumar et al., GCN #29539) at ~ 1.7 days after the burst. Preliminary photometry is following : Date UT start Filter Exp. (s) Mag err 2021-02-19 15:47:38 r 4*900 22.32 0.17 2021-02-20 16:30:35 r 10*300 >22.60 ---- The reported magnitudes are calibrated with the nearby PanSTARRS field and are not corrected for Galactic extinction in the direction of the burst. Using our data along with the data taken from Zhu et al. GCN #29523; Zheng et al. GCN #29533; Kumar et al., GCN #29539, we obtain a decay index of 0.47 +- 0.03 consistent with the value quoted by Shrestha et al. # GCN 29535. .