Candidate gravitational microlensing events for future direct lens imaging

C. B. Henderson, H. Park, T. Sumi, A. Udalski, A. Gould, Y. Tsapras, C. Han*, B. S. Gaudi, V. Bozza, F. Abe, D. P. Bennett, I. A. Bond, C. S. Botzler, M. Freeman, A. Fukui, D. Fukunaga, Y. Itow, N. Koshimoto, C. H. Ling, K. MasudaY. Matsubara, Y. Muraki, S. Namba, K. Ohnishi, N. J. Rattenbury, To Saito, D. J. Sullivan, D. Suzuki, W. L. Sweatman, P. J. Tristram, N. Tsurumi, K. Wada, N. Yamai, P. C. M. Yock, A. Yonehara, M. K. Szymanski, M. Kubiak, G. Pietrzynski, I. Soszynski, J. Skowron, S. Kozlowski, R. Poleski, Daniel Martyn Bramich, Paul Browne, Martin Dominik, Keith Douglas Horne, Markus Peter Gerhard Hundertmark, Roberto Jose Figuera Jaimes, Noé Kains, Rachel Amanda Street, MOA Collaboration, OGLE Collaboration, μFUN Collaboration, RoboNet Collaboration

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

13 Citations (Scopus)


The mass of the lenses giving rise to Galactic microlensing events can be constrained by measuring the relative lens-source proper motion and lens flux. The flux of the lens can be separated from that of the source, companions to the source, and unrelated nearby stars with high-resolution images taken when the lens and source are spatially resolved. For typical ground-based adaptive optics (AO) or space-based observations, this requires either inordinately long time baselines or high relative proper motions. We provide a list of microlensing events toward the Galactic bulge with high relative lens-source proper motion that are therefore good candidates for constraining the lens mass with future high-resolution imaging. We investigate all events from 2004 to 2013 that display detectable finite-source effects, a feature that allows us to measure the proper motion. In total, we present 20 events with μ ≥ 8 mas yr–1.
Of these, 14 were culled from previous analyses while 6 are new, including OGLE-2004-BLG-368, MOA-2005-BLG-36, OGLE-2012-BLG-0211, OGLE-2012-BLG-0456, MOA-2012-BLG-532, and MOA-2013-BLG-029. In ≤12 yr from the time of each event the lens and source of each event will be sufficiently separated for ground-based telescopes with AO systems or space telescopes to resolve each component and further characterize the lens system. Furthermore, for the most recent events, comparison of the lens flux estimates from images taken immediately to those estimated from images taken when the lens and source are resolved can be used to empirically check the robustness of the single-epoch method currently being used to estimate lens masses for many events.

Original languageEnglish
Article number71
Number of pages11
JournalAstrophysical Journal
Issue number1
Early online date24 Sept 2014
Publication statusPublished - 10 Oct 2014


  • Binaries: general
  • Gravitational lensing: micro
  • Galactic bulge
  • Binary-lens
  • Chemical evolution
  • Planetary companion
  • Orbital motion
  • Optical depth
  • Mass planet
  • Brown dwarf
  • Parallax


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