Observation of Celestial Gamma-ray Objects with Imaging Cerenkov Telescope

观测超高能伽马射线是天文学的最后前沿。本研究的目的是建造一个探测1000GeV=1TeV高能伽马射线的望远镜，然后在这个能区增加来自各种天体的更多观测数据。(1)我们把一个3.8米的抛物面望远镜运到了澳大利亚。通过设置目前分辨率最高的220个光电倍增管摄像机，加上电子电路和计算机系统，使成像切伦科夫望远镜投入使用。该装置的角分辨率为-0.1ﾟ，能够将宇宙线本底降低约100倍。已经针对年轻的脉冲星、超新星遗迹和活动星系核进行了观测，这些恒星以GeV的能量发射伽马射线。(2)在PSR1706-44上探测到TeV伽马射线信号。这是该天体发出的第一个TeV伽马射线的迹象，使其成为仅次于螃蟹的第二个银河系TeV伽马射线发射器。(3)在Crab脉冲星/星云中也发现了6TeV伽马射线的证据，这使我们能够与美国惠普尔天文台的望远镜特性进行比较，并提供关于该天体的新数据。有了这些结果，我们就可以朝着建立超高能伽马射线天文学的最终目标迈出一步。观测仍在进行中，我们预计会有更多来自其他天体的观测数据。

Observation of very high energy gamma-rays is the last frontier in astronomy. The present research was commenced with a purpose to construct a telescope for detecting energetic gamma-rays at 1000 GeV=1TeV,and then to add more observational data in this energy region from various celestial objects. (1) We transported a 3.8 m parabolic telescope to Australia. By setting a camera of 220 photomultiplier tubes which has the current highest resolution and by adding a system of electronics circuits and a computer, an imaging Cerenkov telescope was made into operation. The apparatus has an angular resolution of -0.1ﾟ with a capability of reducing cosmic ray background by a factor of about 100. Observation has been done aiming at young pulsars, supernova remnants and active galactic nuclei which are known to emit gamma-rays at GeV energies. (2) A signal of TeV gamma-rays was detected from PSR1706-44. It is the first indication of TeV gamma-rays from this object, making it the second Galactic TeV gamma-ray emitter next to the Crab. (3) An evidence of gamma-rays of 6 TeV was found also from the Crab pulsar/nebula, which enables us to calibrate the characteristics of the telescope in comparison with the one of the Whipple Observatory in USA,as well as to provide with new data on this object. With these results, we could start a step toward our final goal of establishing very high energy gamma-ray astronomy. The observation is still under way, and we expect more observational data from many other objects.