Systematic KMTNet Planetary Anomaly Search. XIII. Complete Sample of 2021 Prime Field Planets

October 2026 • 2026AJ....172..192S

Authors • Shin, In-Gu • Yee, Jennifer C. • Zang, Weicheng • Han, Cheongho • Gould, Andrew • Mao, Shude • Lee, Chung-Uk • Ryu, Yoon-Hyun • Bond, Ian A. • Sumi, Takahiro • Albrow, Michael D. • Chung, Sun-Ju • Ha Hwang, Kyu- • Jung, Youn Kil • Shvartzvald, Yossi • Yang, Hongjing • Cha, Sang-Mok • Kim, Dong-Jin • Kim, Seung-Lee • Lee, Dong-Joo • Lee, Yongseok • Park, Byeong-Gon • Pogge, Richard W. • Kmtnet Collaboration • Abe, Fumio • Bennett, David P. • Bhattacharya, Aparna • Hamada, Ryusei • Hirao, Yuki • Ishitani Silva, Stela • Miyazaki, Shota • Muraki, Yasushi • Nunota, Kansuke • Olmschenk, Greg • Ranc, Clément • Rattenbury, Nicholas J. • Satoh, Yuki K. • Suzuki, Daisuke • Tamaoki, Takuto • Terry, Sean K. • Tristram, Paul J. • Vandorou, Aikaterini • Yama, Hibiki • Moa Collaboration

Abstract • The Systematic KMTNet Planetary Anomaly Search series was conducted using the KMTNet data archived from 2016--2019. From this first phase of the series, we reported a total of 50 planetary systems hidden in the data archive, which represent about 35% of the total microlensing planets discovered from 2016--2019, demonstrating that this semi-machine-based search is a crucial channel for building a complete microlensing planet sample. We continue this series for 2021 and beyond to expand the microlensing planet sample. In this work for the 2021 KMTNet high-cadence fields (Prime fields), we find seven hidden planetary systems and three planet candidates. These new planets represent about 33% of the total microlensing planets discovered within the Prime fields observed during the 2021 bulge season. While the by-eye search is the primary channel for detecting microlensing planets (i.e., two-thirds of microlensing planet discoveries), this work clearly shows that a systematic search series is still necessary for constructing a complete microlensing planet sample. Such a sample is essential for conducting unbiased statistical studies of planet demographics in our Galaxy. Datasets for all of the events used for analyses in this work are publicly available: doi: https://zenodo.org/records/21472225.

Links

• ELECTR https://doi.org/10.3847/1538-3881/ae9864