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Session 83 - Gravitational Lensing.
Display session, Friday, January 09
For the past 2.5 years, the Global Microlensing Alert Network (GMAN) has been undertaking a follow-up survey of stars undergoing microlensing towards the Galactic bulge, LMC, and SMC. We present here GMAN photometry on microlensed stars at the \sim 1 % level which detects :
* Parallax motion due to the Earth's orbit around the sun, which allows a measurement of the velocity vector of the lens relative to the solar position. Through this additional information, we are able to estimate the mass and distance of the lensing object. An ensemble of parallax events will measure the kinematics of the lensing population.
* Deviations due to the lens transiting the source face. We may then use the lens as a novel tool to measure center-to-limb variations in the stellar spectrum. These deviations provide a measure of the lens proper motion, and allow an estimate of lens mass and distance.
* Evidence for microlensing of an unresolved binary system in the LMC, indicating the event may be due to LMC/LMC self-lensing.
* Lensing by binary systems, including detection of the extreme caustic structure expected of binary lenses, and short deviations due to possible planetary mass companions to the primary lens.
Program listing for Friday