TITLE: GCN CIRCULAR NUMBER: 28773 SUBJECT: GRB 201020B: follow-up observations with Savelli Telescope DATE: 20/10/24 19:34:16 GMT FROM: Luciano Nicastro at INAF-OAS L. Nicastro (INAF-OAS), A. Brosio (Osservatorio Astronomico Lilio), S. Savaglio (UNICAL) We observed the afterglow (Lipunov et al., GCN 28718; Xu et al., GCN 28719; Belkin et al., GCN 28725; Breeveld & Lien, GCN 28743; Vinko et al., GCN 28750; Kumar et al., GCN 28753; Kann et al., GCN 28765; Belkin et al., GCN 28768; Dimple et al., GCN 28772) of GRB 201020B (Fermi GBM Team, GCN 28702; Fermi GBM detection: Malacaria & Meegan, GCN 28710; Fermi LAT detection: Arimoto et al., GCN 28716; AGILE detection: Ursi et al., GCN 28714; Konus-Wind detection: Ridnaia et al., GCN 28723) with the 0.5m telescope of the Osservatorio Astronomico Lilio, located in Savelli (South Italy). Date / UT-mid JD T-T0(hr) Exp(s) Filter Mag (AB) 2020-10-21T18:47:48.85 | 2459144.28320 | 25.23 | 5 x 300 | Sloan-r | 19.60 +/- 0.12 2020-10-21T19:35:28.72 | 2459144.31630 | 26.03 | 5 x 300 | Sloan-g | 20.02 +/- 0.15 Magnitudes, calibrated wrt nearby PanSTARRS field stars, are not corrected for galactic extinction. Fog prevented us from performing further observations in the following nights.