Development of High Energy Gamma Ray Telescope with High Angular Resolution and Observation of Gamma Ray Objects in the Southern Sky

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An imaging Cerenkov telescope with an aperture of 3.8 m diameter started operation in January 1992 in South Australia. The telescope was brought to Australia at the beginning of 1991. After assembling the telescope, the focussing quality of mirror was checked by seeing a star image. The blur was less than 0.1ﾟ. The tracking accuracy was found as good as - <plus-minus>0.01ﾟ by seeing several stars in different directionThe phototube camera of the telescope has a small pixel size of 0.15ﾟ x 0.15ﾟ with a total field of view of about 2.5ﾟ diameter. The telescope, the first imaging telescope in the southern hemisphere, was aimed at the Vela Pulsar/nebula and Cen A during the period from January to March in 1992.The obtained data was analyzed to reconstruct Cerenkov images of cosmic ray particles. The general feature of the image appear consistent with what is expected from simulation calculation. A new thing about this imaging telescope is that the arrival time of photons in each phototube is measured. The background lights of night sky should have a uniform distribution of arrival time, which, experimentally proved by selecting the lights separated from a clustering signals of air shower image, will be useful to reduce the contamination of the background light in signal.Further analysis and continuing accumulation of data are to be done as well as improvements of observation technique, such as choosing the best way of making a trigger signal for lower energy threshold and constructing a camera of a wider field of view with a larger number of phototubes. The telescope is going to be used to achieve a simultaneous observation with the BIG RAT telescope of Adelaide University.