Аннотация:The results of LIGO/Virgo S200302c (O3) error-box optical inspection by MASTER are presented. We observed 4242 square degrees square degrees inside 3σ error box during 1 month. We present MASTER OT J141401.39–483305.7, MASTER OT J215856.95–392909.6, MASTER OT J061642.05+435617.9, MASTER OT J052817.95+672801.4—optical transients found by the MASTER auto-detection system during this inspection as the result of a survey of large error-fields, indicating the efficiency of MASTER observational strategy.