The results of simultaneous TESS and multiband photometric observations of BL Lac during a high activity

For the blazar BL Lac, we analyze data from TESS and multiband observations that were obtained using the MTM-500 telescope of the Crimean Astrophysical Observatory from 1.09.2022 to 30.09.2022. During this period, BL Lac showed strong variability, both accompanied and unaccompanied by changes in spectral index. The shortest characteristic variability times are mainly in the range from 0.2 to 1 day and do not depend on the object brightness, the spectral index, and the average amplitude of the variability within the corresponding intervals of the light curve. It indicates that the mechanisms of short-term variability are characterized by two or more independent parameters.