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

1992年1月，直径3.8米的切伦科夫成像望远镜在南澳大利亚开始运行。该望远镜于1991年初被带到澳大利亚。在组装好望远镜后，通过观察恒星图像来检查镜面的聚焦质量。模糊度小于0.1‰。通过观察不同方向的几颗恒星，发现其跟踪精度可达- <±>0.01。望远镜的光射管相机像素尺寸较小，为0.15 x 0.15，总视场直径约为2.5。该望远镜是南半球第一台成像望远镜，于1992年1月至3月期间瞄准船帆座脉冲星/星云和半人马座A。对获得的数据进行分析，重建宇宙射线粒子的切伦科夫图像。图像的总体特征与仿真计算结果一致。这台成像望远镜的一个新特点是可以测量每个光电管中光子到达的时间。夜空背景光应具有均匀的到达时间分布，通过从气淋图像的聚类信号中选取分离的光，实验证明了这一点，有助于减少背景光对信号的污染。进一步的分析和数据的持续积累，以及观测技术的改进，如选择较低能量阈值的触发信号的最佳方式，用更多的光电管构建更大视场的相机。该望远镜将与阿德莱德大学的BIG RAT望远镜进行同步观测。

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.