The foundation of millimeter wave VLBI station at Kagoshima

射电天文学家已经开发出将分散在全球各地的射电望远镜的信号组合在一起的方法，创造出一个直径数千公里的有效孔径。这项被称为甚长基线干涉仪(VLBI)的技术将天文角度分辨率测量提高到了新的高度。在日本，两台毫米的VLBI望远镜一直在运行。其中一个是野山(NRO)的45米望远镜，另一个是鹿岛(CRL)的34米望远镜。最近，一台新的毫米VLBI望远镜在水泽(水泽天体地球动力学观测站)建成。然而，这些望远镜位于日本北部。我们的项目是在日本南部建造一个新的毫米VLBI站，创造一个日本岛屿大小的有效孔径。这台6米长的望远镜从野山射电天文台搬到鹿儿岛。我们在1992年完成了天线的建造并安装了一个22 GHz的冷却接收器。由于该天线很小，mm-VLBI观测…更多的需要大量的技术努力：该系统与目前的VLBI实践相比有两个明显的特点，以提高灵敏度。一个是具有高速采样器和大容量存储器的突发模式操作的能力。另一种是一种新的带宽合成器模式，使用高速采样器和滤波器来代替视频转换器。这些新方法使用光缆传输宽带(2 GHz)。第一，鹿儿岛-野山-水泽干涉仪VLBI实验于1993年与野山射电天文台和水泽天文台合作完成。该网最长基线为1300公里，在22 GHz处的条纹间隔为2毫角秒。最近，我们开始了对H_2O脉泽源的VLBI监测，以探测脉泽在几个月内的视运动。这些数据将为星际云的内部工作提供不可替代的见解。此外，我们正在推进43 GHz VLBI观测计划，并将在1995年安装一个43 GHz冷接收器。较少

Radio astronomers have developted methods for combining signals from radio telescopes scattered around the globe, creationg an effective aperture thousands km across. This technique, known as very long base line interferometer (VLBI), has elevated astronomical angular resolution measurements to new heights. In Japan, two mm VLBI telescopes have been performing. One in 45 m telescope at Nobeyama (NRO), and the otheris 34 m telescope at Kashima (CRL). Recently, a new mm VLBI telescope was constructed at Mizusawa (Mizusawa Astrogeodynamics Observatory). However, these telescopes are situated in the northern part of Japan. Our project is to construct a new mm VLBI station in the southern part of Japan, creating an effective aperture with the size of Japanese Islands. The 6m telescope was moved from Nobeyama Radio Observatory to Kagoshima. We finished the construction of the antenna and installed a 22 GHz cooled receiver in 1992. Owing to the smallness of this antenna, mm-VLBI observations … More require substantial technical efforts : The system has two distinctive characteristics as compared with current VLBI practice in order to improve thesensitivity. One is the capability of a burst mode operation with a high speed sampller and a large capacity memory. The other is a new bandwidth synthesizer mode operation using both high speed sampler and filters instead of video converters. Optical fiber cables are used for transmission of wide IF band (2GHz) for these new methods.First Kagoshima-Nobeyama-Mizusawa interferometer VLBI experiment was done in 1993 with collaboration from the Nobeyama Radio Observatory, and Mizusawa Observatory. The longest baseline of this network is 1300 km which provides a fringe separation of 2 milliarcsecont at 22 GHz.Recently, we started the monitor VLBI observations of H_2O maser sources in order to detect the apparent motions of masers in months. These data will provide irreplaceable insights into the inner working of interstellar clouds.Also, we are now pushing a plan of 43 GHz VLBI observations and will install a 43 GHz cold receiver in 1995. Less