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Gravitational Lensing by Stars and Machos and the Orbital Motion of the Earth

Published online by Cambridge University Press:  07 August 2017

M. Hosokawa ,
K. Ohnishi ,
T. Fukushima  and
M. Takeuti
M. Hosokawa
Affiliation:
Communications Research Laboratory, Koganei, Tokyo 184, Japan. e-mail hosokawa@crl.go.jp
K. Ohnishi
Affiliation:
Kansai Advanced Research Center, Communications Research Laboratory, Kobe 651-24, Japan. e-mail ohnishi@crl.go.jp
T. Fukushima
Affiliation:
National Astronomical Observatory, Mitaka, Tokyo 181, Japan. e-mail toshio@spacetime.mtk.nao.ac.jp
M. Takeuti
Affiliation:
Astronomical Institute, Tohoku University, Aoba-ku, Sendai, 980 Japan. e-mail i4a0s4d@JPNTOHOK.ecip.tohok.ac.jp

Abstract

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We showed that it is feasible to measure the mass of a single star by observing the variation of gravitational deflection caused by the orbital motion of the Earth. When the distance of a star is less than 60 pc and some appropriate sources are within 1 arcsec. in its background, not only the distance but also the mass of the star may be determined by measuring the deflection with an accuracy of 10 μ arcsec. In the case of photometric microlensing by a MACHO, the observation of astrometric gravitational deflection is also useful. By measuring the separation between the primary image and the secondary image, the ratio of mass to distance of the MACHO will be obtained. Further, the orbital motion of the Earth modifying the light curve of the source is discussed.

Type
2. Current and Future Needs for Very Accurate Astrometry
Information
Symposium - International Astronomical Union , Volume 166: Astronomical and Astrophysical Objectives of Sub-Milliarcsecond Optical Astrometry , 1995 , pp. 305 - 308
Copyright
Copyright © Kluwer 1995 

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