The construction of 43GHz VLBI network and the project search for VLBI radio sources of phase-referencing VLBI astrometry with VERA.

VERA （VLBI Exploration of Radio Astrometry，简称VERA）是一种新型的VLBI天文测量仪器，主要目的是通过天文脉射源的高精度相位参考VLBI天文测量来研究我们银河系的结构和动力学。VERA的双波束天线系统将使我们能够同时观测星系脉泽和星系外参考源，以消除大气波动。为了使VERA达到10μ as级的精度，使我们能够获得整个银河系中脉泽源的视差，要求脉泽和参考源必须位于彼此2°以内。由于作为主要目标的H2O（22GHz）和SiO（43GHz）脉泽主要集中在银道面上，因此需要大量的参考源分布在银道面上。因此，在银河面寻找VLBI源对VERA的成功是必不可少的。为了寻找43GHz VLBI源，我们开始在本基金鹿岛空间研究中心通信研究实验室的34m天线上安装43GHz冷却接收机。通过这个，我们将使用这个34米望远镜和Nobeyama 45米望远镜开始对银河面的连续射电源进行43GHz的调查。我们构造了小型冷却杜瓦瓶，并成功地冷却了接收器。此外，我们整合了本地振荡器（这个Grant-IN-Aid），并将这些组件安装在34米望远镜上。系统噪声温度（含大气损耗）为300K。在这次试验观察中，出现了非常严重的问题。当天线倾斜时，由于副反射镜的弯曲和下垂，天线指向精度变得很差。这个棘手的问题主要是由鹿儿岛大学的研究生森崎忠解决的。他还建立了高分辨率声光光谱仪。

VERA (VLBI Exploration of Radio Astrometry) is a new VLBI ax mainly aimed at study of the structure and dynamics of our Galaxy through high precision phase-referencing VLBI astrometry of astronomical maser sources. VERA, with its dual-beam antenna system, will enable us to observe a galactic maser and an extra-galactic reference source simultaneously in order to remove the atmospheric fluctuation. In order for VERA to achieve a 10μ as level accuracy, allowing us to obtain parallaxes of maser sources in the whole Galaxy, it is required that the maser and reference source must be located within 2°each other. This requires a large number of reference sources spreading over Galactic plane because H2O(22GHz) and SiO(43GHz) masers which are the main targets, are mostly concentrated in the galactic plane. Hence the search for VLBI sources in the galactic plane is indispensable to the success of VERA. In order to search for 43GHz VLBI sources, we started to install the 43GHz cooled receiver to 34m antenna which belongs to Kashima Space Research Center, Communications Research Laboratory in these Funds. By this we will start a 43GHz survey of continuum radio sources in the galactic plane using this 34m telescope and Nobeyama 45m telescope. We constructed small-sized cooled dewar and has succeeded in cooling the receiver. Further, we incorporated the Local oscillator (this Grant-IN-Aid) and installed these components in 34m telescope. The system noise temperature, including atmospheric loss, was 300K. In this test observations, very serious problems arosed. As the antenna inclined, the antenna pointing accuracy become significantly poor due to both the bending and hanging down of the subreflector. This knotty problems was mainly settled by Satoru Morisaki, a graduate student of Kagoshima University. He also set up high-resolution acousto-optical spectrometers.