Search of dark matter by microlensing observations

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An extremly sensitive 'gravitational microlensing' technique, that was originally proposed by Einstein, is being used at the Mt.John University Observatory by a Japan/NZ collaboration MOA to carry out various fundamental measurements. The collaboration brings together resources and expertise from several NZ and Japanese institutions. Additional US and Australian expertise and resources are involved through MOA's participation in a world-wide network of southern observatories all using the microlensing technique. The network is known as GMAN.Both MOA and GMAN utilise Mt.John's competitive edge in terms of latitude and longitude for observations of the Magellanic Clouds. What we have discoverd are as follows :1) The composition of the halo of the Galaxy is unknown. The MOA group has found that it is comprised of<10% of low-mass brown dwarf stars, consistent with other groups. In May 1998, observations will be made with new CCD camera and improved search technique.2) Discovery-of an extra Jupitor in July 24th 1997. It has been confirmed that the microlensing technique has the required sensitivity for the detection of extra-solar planets. Round-the-clock observations were made by the GMAN network, and by another network known as PLANET,a possible example of planet was found. Again in May 1998, a much larger CCD camera with 24 million rather 9 million pixels will be used at Mt.John, and the data analysis will be carried out on-line. Statistically significant data on the frequency of stars with planetary systems similar to ours, potentially capable of supporting life, are expected to be discovered.3) Detail structure of stellar atmosphere has been done. Using binary lensing event 97-28, a very detailed study of a distant star was made.