MASTER optical observations of the blazar TXS0506+056 during the IC170922A

We present MASTER Global Robotic Net (Lipunov et al. 2010) earliest optical alert observations of IceCube-170922A error box. We discovered fast variability of blazar TXS 0506+056 27 sec after notice time (73s after the trigger time) at 2017-09-22 20:55:43 UT by MASTER-Tavrida robotic telescope. MASTER found the blazar TXS 0506+056 to be in the off-state after one minute and then switched to the on-state no later than two hours after the event. The effect is observed at a 50-sigma significance level. We also analysed own unique 16-years light curve of blazar TXS 0506+056 (518 data set).