Simultaneous observation of time variable TeV gamma-ray objects in optical wavelength and monitoring of night sky

活动星系核的伽马射线发射在时间上变化很大，据报道其变化的时间尺度短至15分钟。其他波长的观测应与伽马射线观测在同一经度同时进行。在这项研究中，我们在南澳大利亚伍默拉的KANGAROO伽玛射线望远镜旁边设置了一个小型光学望远镜，同时研究短时间变异性。同时对伽玛射线天体周围的夜空进行监测，以保证大气切伦科夫法观测伽玛射线的质量。今年我们在千叶柏华校区的光学望远镜系统进行了测试，并将其运送到伍默拉进行测试观测。利用Linux操作系统开发了全自动观测系统，实现了对网络的充分利用。它控制望远镜支架并从冷却的CCD相机获取数据。在柏华，我们成功地观测到了一个AGN， Mrk421。在伍默拉，我们不得不每天晚上设置望远镜轴，因为自动望远镜遮挡不及时，每天晚上需要很长时间。然而，我们可以用不同的天顶角和约翰逊UBVRI滤镜来测量恒星。通过与模型大气计算数据的比较，我们可以了解到Woomera大气的性质，这是我们在Cherenkov观测中根据观测到的光子数估计伽玛射线能量的重要信息。

Gamma-ray emission from Active Galactic Nuclei is highly variable in time and the reported time scale of its variation is as short as 15 minutes. Simultaneous observation at other wavelength should be done at the same longitude as gamma-ray observation.Is this research we set a small optical telescope next to the KANGAROO gamma-ray telescope in Woomera, South Australia to study short time variability simultaneously. Also we aim to monitor night sky condition around the gamma-ray objects for quality check of gamma-ray observation by atmospheric Cherenkov method.This year we operated the optical telescope system in Kashiwa campus, Chiba, as a test and shipped it to Woomera for test observation. We developed a full automated observation system using Linux operating system so that we can utilize network. It controls the telescope mount and obtains data from the cooled CCD camera. At Kashiwa we succeeded in observing an AGN, Mrk421. At Woomera, we had to setup the telescope axis every night since the automated telescope shelter was not in time which required long time each night. However, we could measure stars at various zenith angles and with Johnson UBVRI filters. Comparing data with the model calculation of atmosphere, we could know the properties of atmosphere in Woomera, which is an important information when we estimate gamma-ray energy from observed number of photons in Cherenkov observation.