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Abstract
We present the first example of binary microlensing for which the parameter measurements can be verified (or contradicted) by future Doppler observations. This test is made possible by a confluence of two relatively unusual circumstances. First, the binary lens is bright enough (I = 15.6) to permit Doppler measurements. Second, we measure not only the usual seven binarylens parameters, but also the "microlens parallax" (which yields the binary mass) and two components of the instantaneous orbital velocity. Thus, we measure, effectively, six "Kepler+1" parameters (two instantaneous positions, two instantaneous velocities, the binary total mass, and the mass ratio). Since Doppler observations of the brighter binary component determine five Kepler parameters (period, velocity amplitude, eccentricity, phase, and position of periapsis), while the same spectroscopy yields the mass of the primary, the combined Doppler + microlensing observations would be overconstrained by 6 + (5 + 1)  (7 + 1) = 4 degrees of freedom. This makes possible an extremely strong test of the microlensing solution. We also introduce a uniform microlensing notation for single and binary lenses, define conventions, summarize all known microlensing degeneracies, and extend a set of parameters to describe full Keplerian motion of the binary lenses.
Original language  English 

Article number  87 
Number of pages  21 
Journal  Astrophysical Journal 
Volume  738 
Issue number  1 
DOIs  
Publication status  Published  1 Sept 2011 
Keywords
 binaries: general
 Galaxy: bulge
 gravitational lensing: micro
 DIFFERENCE IMAGEANALYSIS
 GALACTIC BULGE
 JUPITER/SATURN ANALOG
 PLANET PHOTOMETRY
 LENS
 STARS
 DISCOVERY
 CALIBRATION
 DEGENERACY
 ASTROMETRY
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Dive into the research topics of 'BINARY MICROLENSING EVENT OGLE2009BLG020 GIVES VERIFIABLE MASS, DISTANCE, AND ORBIT PREDICTIONS'. Together they form a unique fingerprint.Projects
 1 Finished

Astrophysics in St Andrews: Astrophysics in St Andrews / SUPA (Continuan of Rolling Grant  XPP089
Bonnell, I. A., Cameron, A. C., Dominik, M., Driver, S. P., Greaves, J. S., Horne, K. D., Jardine, M. M., Wood, K. & Zhao, H.
Science & Technology Facilities Council
1/04/09 → 31/03/12
Project: Standard