Systematic KMTNet planetary anomaly search. IV. Complete sample of 2019 prime-field

We report the complete statistical planetary sample from the prime fields (Γ ≥ 2 h<SUP>-1</SUP>) of the 2019 Korea Microlensing Telescope Network (KMTNet) microlensing survey. We develop the optimized KMTNet AnomalyFinder algorithm and apply it to the 2019 KMTNet prime fields. We find a total of 13 homogeneously selected planets and report the analysis of three planetary events, KMT-2019-BLG-(1042,1552,2974). The planet-host mass ratios, q, for the three planetary events are 6.34 × 10<SUP>-4</SUP>, 4.89 × 10<SUP>-3</SUP>, and 6.18 × 10<SUP>-4</SUP>, respectively. A Bayesian analysis indicates the three planets are all cold giant planets beyond the snow line of their host stars. The 13 planets are basically uniform in log q over the range -5.0 < log q < -1.5. This result suggests that the planets below q<SUB>break</SUB> = 1.7 × 10<SUP>-4</SUP> proposed by the MOA-II survey may be more common than previously believed. This work is an early component of a large project to determine the KMTNet mass-ratio function, and the whole sample of 2016-2019 KMTNet events should contain about 120 planets.