TITLE: GCN CIRCULAR NUMBER: 28776 SUBJECT: GRB 201020B: HCT and GIT continued optical follow-up observations DATE: 20/10/25 09:04:20 GMT FROM: Harsh Kumar at Indian Inst of Tech,Bombay H. Kumar(IITB), S. Kiran (IIA), J.Stanzin (IAO), V. Bhalerao(IITB), G. C. Anupama(IIA), S. Barway(IIA) report on behalf of the HCT team: We followed-up GRB 201020B reported by Fermi GBM Team (GCN #28702, also see: V. Lipunov et. al., GCN #28718; D. Xu et. al., GCN #28719) with 2.0m Himalayan Chandra Telescope (HCT) and 0.7m GROWTH-India Telescope (GIT). We obtained a series of 300-sec exposures in the Rc, r filters. Afterglow was clearly detected at a position consistent with V. Lipunov et. al., GCN #28718; D. Xu et. al., GCN #28719. Here are the photometric results from HCT & GIT observations:- ------------------------------------------------------- JD (mid) | T_mid-T0(hrs) | Filter | Mag | Telescope | ------------------------------------------------------- 2459145.40625 | 52.22 | r | 21.01 +/- 0.04 | GIT | 2459146.32699 | 74.80 | Rc | 21.28 +/- 0.04 | HCT | ------------------------------------------------------- Our results are consistent with the power-law decay of 1.67 reported in S. Belkin et al. GCN #28768; H. Kumar et al. GCN #28753. These observations were carried out under the ToO program HCT-2020-C3-P6. We thank HCT and GIT staff for undertaking the observations. The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7 degree field of view, set up by the Indian Institute of Astrophysics and the Indian Institute of Technology Bombay with support from the Indo-US Science and Technology Forum (IUSSTF) and the Science and Engineering Research Board (SERB) of the Department of Science and Technology (DST), Government of India (https://sites.google.com/view/growthindia/). It is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA).