KMT-2025-BLG-1616Lb: First Microlensing Bound Planet From DREAMS

Yang 杨, Hongjing 弘靖; Zang 臧, Weicheng 伟呈; Ryu, Yoon-Hyun; Sumi, Takahiro; Zhang 张, Jiyuan 纪元; Li 李, Hongyu 弘禹; Han, Cheongho; Tang, Yuchen; Qian, Qiyue; Li, Zhixing; Shang, Yuxin; Shan, Xikai; Mao, Shude; Damke, Guillermo; Zenteno, Alfredo; Heathcote, Steve; Boutsia, Konstantina; Mróz, Przemek; Zhao, Xiurui; Penny, Matthew; Terry, Sean; Tamburo, Patrick; Cunningham, Timothy; Ye, Quanzhi; Peng, Eric W.; Street, Rachel; Kruszyńska, Katarzyna; Bachelet, Etienne; Tsapras, Yiannis; Hundertmark, Markus; (The DREAMS Collaboration); Albrow, Michael D.; Chung, Sun-Ju; Gould, Andrew; Hwang, Kyu-Ha; Jung, Youn Kil; Shin, In-Gu; Shvartzvald, Yossi; Yee, Jennifer C.; Kim, Dong-Jin; Lee, Chung-Uk; Park, Byeong-Gon; (The KMTNet Collaboration); Bennett, David P.; Bond, Ian A.; Hamada, Ryusei; Hirao, Yuki; Idei, Asahi; Makida, Shuma; Miyazaki, Shota; Nagai, Tutumi; Nagano, Togo; Nakayama, Seiya; Nishio, Mayu; Nunota, Kansuke; Ogawa, Ryo; Oishi, Ryunosuke; Okumoto, Yui; Rattenbury, Nicholas J.; Satoh, Yuki K.; Suzuki, Daisuke; Tamura, Motohide; Tamaoki, Takuto; Yama, Hibiki; (The PRIME Collaboration)

doi:10.3847/1538-3881/ae36ac

Published March 2026 | Version Published

Journal Article Open

KMT-2025-BLG-1616Lb: First Microlensing Bound Planet From DREAMS

1. Westlake University
2. Harvard-Smithsonian Center for Astrophysics
3. Korea Astronomy and Space Science Institute
4. Osaka University
5. Tsinghua University
6. Chungbuk National University
7. Cerro Tololo Inter-American Observatory
8. University of Warsaw
9. California Institute of Technology
10. Louisiana State University
11. Goddard Space Flight Center
12. University of Maryland, College Park
13. Boston University
14. NOIRLab
15. Las Cumbres Observatory Global Telescope Network
16. Infrared Processing and Analysis Center
17. Heidelberg University
18. University of Canterbury
19. Max Planck Institute for Astronomy
20. The Ohio State University
21. Korea University of Science and Technology
22. Weizmann Institute of Science
23. Massey University
24. University of Tokyo
25. Institute of Space and Astronautical Science
26. University of Auckland
27. Kanto Gakuin University
28. Astrobiology Center

We present observations and analysis of the bound planetary microlensing event KMT-2025-BLG-1616. The planetary signal was captured by the Korea Microlensing Telescope Network and the Dark Energy Camera Rogue Earths and Mars Survey (DREAMS). DREAMS’s minute-cadence observations break the central/resonant degeneracy in the binary-lens models. The color of the faint source star (I = 22) is measured from the DREAMS’s r − z color. The planetary system has a planet-host mass ratio of q ∼ 5 × 10⁻⁴. A Bayesian analysis yields a host-star mass of ∼0.3 M_⊙, a planetary mass of ∼40 M_⊕, a projected planet-host separation of ∼1.6 au, and a lens distance of ∼7.5 kpc. Based on the photometric precision achieved by DREAMS for this event, we simulate free-floating planet (FFP) detections and find that DREAMS is sensitive to Mars-mass FFPs in the Galactic bulge and Moon-mass FFPs in the Galactic disk.

Copyright and License

© 2026. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI.

Acknowledgement

H.Y. acknowledge support by the China Postdoctoral Science Foundation (No. 2024M762938). W.Z. acknowledges the support from the Harvard-Smithsonian Center for Astrophysics through the CfA Fellowship. H.Y., W.Z., J.Z., H.L., Y.T., Q.Q., Z.L., Y.S., X.S., and S.M. acknowledge support by the National Natural Science Foundation of China (grant No. 12133005). This work is part of the ET space mission which is funded by the China’s Space Origins Exploration Program. This research has made use of the KMTNet system operated by the Korea Astronomy and Space Science Institute (KASI) at three host sites of CTIO in Chile, SAAO in South Africa, and SSO in Australia. Data transfer from the host site to KASI was supported by the Korea Research Environment Open NETwork (KREONET). This research was supported by KASI under the R&D program (project No. 2025-1-830-05) supervised by the Ministry of Science and ICT. The PRIME project is supported by JSPS KAKENHI grant Nos. JP16H06287, JP22H00153, JP25H00668, JP19KK0082, JP20H04754, JP24H01811, and JPJSCCA20210003. The PRIME project acknowledges a financial support by Astrobiology Center. Work by J.C.Y. acknowledge support from N.S.F grant No. AST-2108414. Work by C.H. was supported by the grants of National Research Foundation of Korea (2019R1A2C2085965 and 2020R1A4A2002885). Y.S. acknowledges support from BSF grant No. 2020740. R.A.S. and K.K. acknowledge support from US National Science Foundation grant 2206828.

This project used data obtained with the Dark Energy Camera (DECam), which was constructed by the Dark Energy Survey (DES) collaboration. Funding for the DES Projects has been provided by the U.S. Department of Energy, the U.S. National Science Foundation, the Ministry of Science and Education of Spain, the Science and Technology Facilities Council of the United Kingdom, the Higher Education Funding Council for England, the National Center for Supercomputing Applications at the University of Illinois at Urbana-Champaign, the Kavli Institute for Cosmological Physics at the University of Chicago, the Center for Cosmology and Astro-Particle Physics at The Ohio State University, the Mitchell Institute for Fundamental Physics and Astronomy at Texas A&M University, Financiadora de Estudos e Projetos, Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro, Conselho Nacional de Desenvolvimento Científico e Tecnológico and the Ministério da Ciência, Tecnologia e Inovação, the Deutsche Forschungsgemeinschaft, and the collaborating institutions in the Dark Energy Survey.

The collaborating institutions are Argonne National Laboratory; the University of California at Santa Cruz; the University of Cambridge; Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid; the University of Chicago; University College London; the DES-Brazil Consortium; the University of Edinburgh; the Eidgenössische Technische Hochschule (ETH) Zürich; Fermi National Accelerator Laboratory; the University of Illinois at Urbana-Champaign; the Institut de Ciències de l’Espai (IEEC/CSIC); the Institut de Física d’Altes Energies (IFAE); Lawrence Berkeley National Laboratory; the Ludwig-Maximilians-Universität München and the associated Excellence Cluster Universe; the University of Michigan; NSF NOIRLab; the University of Nottingham; The Ohio State University; the OzDES Membership Consortium; the University of Pennsylvania; the University of Portsmouth; SLAC National Accelerator Laboratory; Stanford University; the University of Sussex; and Texas A&M University.

Based on observations at NSF Cerro Tololo Inter-American Observatory, NSF NOIRLab (NOIRLab Prop. ID 2025A-806294, PI: Weicheng Zang; Prop. ID 2025B-560332, PI: Weicheng Zang & Hongjing Yang), which is managed by the Association of Universities for Research in Astronomy (AURA) under a cooperative agreement with the U.S. National Science Foundation.

Software References

pySIS (M. D. Albrow et al. 2009; H. Yang et al. 2024, 2025), numpy (C. R. Harris et al. 2020), emcee (J. Goodman & J. Weare 2010; D. Foreman-Mackey et al. 2013), Matplotlib (J. D. Hunter 2007), SciPy (P. Virtanen et al. 2020), galpy (J. Bovy 2015), DECam Community Pipeline (F. Valdes et al. 2014).

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Is new version of: Discussion Paper: arXiv:2601.11469 (arXiv)

China Postdoctoral Science Foundation
2024M762938
National Natural Science Foundation of China
12133005
Korea Astronomy and Space Science Institute
2025-1-830-05
Japan Society for the Promotion of Science
JP16H06287
Japan Society for the Promotion of Science
JP22H00153
Japan Society for the Promotion of Science
JP25H00668
Japan Society for the Promotion of Science
JP19KK0082
Japan Society for the Promotion of Science
JP20H04754
Japan Society for the Promotion of Science
JP24H01811
Japan Society for the Promotion of Science
JPJSCCA20210003
National Science Foundation
AST-2108414
National Research Foundation of Korea
2019R1A2C2085965
National Research Foundation of Korea
2020R1A4A2002885
United States-Israel Binational Science Foundation
2020740
National Science Foundation
2206828

Submitted: 2025-10-23
Accepted: 2026-01-10
Available: 2026-02-12

Published

Caltech groups: Infrared Processing and Analysis Center (IPAC) , Division of Physics, Mathematics and Astronomy (PMA)
Publication Status: Published

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KMT-2025-BLG-1616Lb: First Microlensing Bound Planet From DREAMS

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