Multicolor-optical observation of the flaring blazar BL Lacertae

The flaring blazar BL Lacertae was in the bright state in optical, X-ray and gamma-ray around August 2020 (ATel #13930, #13933, #13956, #13958, #13963, #13964) and in another bright state around October 2020 (ATel #14065, #14069, #14072, #14081, #14096).