Аннотация:AT2020xss MASTER Global Robotic Net http://observ.pereplet.ru is equipped by identical twin wide field telescope MASTER-II (2*4sq.degrees) and twin very wide field (\raisebox-0.5ex 2*400sq.deg.) cameras MASTER- VWFC at every MASTER observatory (Lipunov et al. 2010) MASTER- Tavrida wide field robotic-telescope (Lipunov et al. GCN #28704) and very wide field cameras observed in alert mode Fermi GRB201020B(GBM GCN #28703, LAT GCN #28716) MASTER auto- detection system (Lipunov et al. 2010, Advances in Astronomy, v.2010, 30L) discovered bright MASTER OT J050152.74+770406.3 (Lipunov et al. GCN #20718) at (RA, Dec2000) = 05h 01m 52.74s +77d 04m 06.3s with m_OT=13.7 at 2020-10-20.73413 UT. We have reference image on 2020-01-02.78682 UT with unfiltered mlim=19.5m.