Аннотация:We present the results of MASTER Global Robotic Net optical observations of the LIGO GW170104 error-box during the LIGO/Virgo O2 run. We observed 3421 square degrees inside 3σ error-field. Dozens of optical transients unrelated to gravitational waves were discovered as the result of MASTER observation strategy, that we presented, including short very bright MASTER optical transients J133017.28+780951.8.