OGLE-2018-BLG-0799Lb: a q ∼2.7 × 10-3planet with Spitzer parallax

Weicheng Zang*, Yossi Shvartzvald, Andrzej Udalski, Jennifer C. Yee, Chung Uk Lee, Takahiro Sumi, Xiangyu Zhang, Hongjing Yang, Shude Mao, Sebastiano Calchi Novati, Andrew Gould, Wei Zhu, Charles A. Beichman, Geoffery Bryden, Sean Carey, B. Scott Gaudi, Calen B. Henderson, Przemek Mróz, Jan Skowron, Radoslaw PoleskiMichał K. Szymański, Igor Soszyński, Paweł Pietrukowicz, Szymon Kozłowski, Krzysztof Ulaczyk, Krzysztof A. Rybicki, Patryk Iwanek, Marcin Wrona, Michael D. Albrow, Sun Ju Chung, Cheongho Han, Kyu Ha Hwang, Youn Kil Jung, Yoon Hyun Ryu, In Gu Shin, Sang Mok Cha, Dong Jin Kim, Hyoun Woo Kim, Seung Lee Kim, Dong Joo Lee, Yongseok Lee, Byeong Gon Park, Richard W. Pogge, Ian A. Bond, Fumio Abe, Richard Barry, David P. Bennett, Aparna Bhattacharya, Martin Donachie, Hirosane Fujii, Akihiko Fukui, Yuki Hirao, Yoshitaka Itow, Rintaro Kirikawa, Iona Kondo, Naoki Koshimoto, Man Cheung Alex Li, Yutaka Matsubara, Yasushi Muraki, Shota Miyazaki, Clément Ranc, Nicholas J. Rattenbury, Yuki Satoh, Hikaru Shoji, Daisuke Suzuki, Yuzuru Tanaka, Paul J. Tristram, Tsubasa Yamawaki, Atsunori Yonehara, Etienne Bachelet, Markus P.G. Hundertmark, R. Figuera Jaimes, Dan Maoz, Matthew T. Penny, Rachel A. Street, Yiannis Tsapras

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


We report the discovery and analysis of a planet in the microlensing event OGLE-2018-BLG-0799. The planetary signal was observed by several ground-based telescopes, and the planet-host mass ratio is q = (2.65 ± 0.16) × 10-3. The ground-based observations yield a constraint on the angular Einstein radius θE, and the microlensing parallax vector πE, is strongly constrained by the Spitzer data. However, the 2019 Spitzer baseline data reveal systematics in the Spitzer photometry, so there is ambiguity in the magnitude of the parallax. In our preferred interpretation, a full Bayesian analysis using a Galactic model indicates that the planetary system is composed of an Mplanet = 0 . 26 + 0 . 22-0 . 11 MJ planet orbiting an Mhost = 0 . 093 +0.082-0.038 M ⊙, at a distance of DL = 3 . 71 + 3 . 24-1 . 70 kpc. An alternate interpretation of the data shifts the localization of the minima along the arc-shaped microlens parallax constraints. This, in turn, yields a more massive host with median mass of 0.13 M⊙ at a distance of 6.3 kpc. This analysis demonstrates the robustness of the osculating circles formalism, but shows that further investigation is needed to assess how systematics affect the specific localization of the microlens parallax vector and, consequently, the inferred physical parameters.

Original languageEnglish
Pages (from-to)5952-5968
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number4
StatePublished - 1 Aug 2022


FundersFunder number
National Aeronautics and Space Administration
Jet Propulsion Laboratory1571564
Jet Propulsion Laboratory
California Institute of Technology1500811, AST-1516842
California Institute of Technology
European Research Council321035
European Research Council
Deutsche ForschungsgemeinschaftWA 1047/11-1
Deutsche Forschungsgemeinschaft
National Natural Science Foundation of China12133005
National Natural Science Foundation of China
Chinese Academy of Sciences
Korea Astronomy and Space Science Institute
National Research Foundation of Korea2017R1A4A1015178, 2019R1A2C2085965
National Research Foundation of Korea
Narodowe Centrum NaukiMAESTRO 2014/14/A/ST9/00121
Narodowe Centrum Nauki
Seventh Framework Programme
Ministry of Finance
National Astronomical Observatories, Chinese Academy of Sciences
Scleroderma Society of OntarioJP17H02871, JSPS24253004, JSPS15H00781, JSPS23340064, JSPS26247023, JP16H06287
Scleroderma Society of Ontario


    • gravitational lensing: micro
    • planets and satellites: detection


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