We report the current status of the 1.85-m mm-submm telescope installed at the Nobeyama Radio Observatory (altitude 1400 m) and the future plan. The scientific goal is to reveal the physical/chemical properties of molecular clouds in the Galaxy by obtaining large-scale distributions of molecular gas with an angular resolution of several arcminutes. A semi-automatic observation system created mainly in Python on Linux-PCs enables effective operations. A large-scale CO J =2–1 survey of the molecular clouds (e.g., Orion-A/B, Cygnus-X/OB7, Taurus- California-Perseus complex, and Galactic Plane), and a pilot survey of emission lines from minor molecular species toward Orion clouds have been conducted so far. The telescope also is providing the opportunities for technical demonstrations of new devices and ideas. For example, the practical realizations of PLM (Path Length Modulator) and waveguide-based sideband separating filter, installation of the newly designed waveguide-based circular polarizer and OMT (Orthomode Transducer), and so on. As the next step, we are now planning to relocate the telescope to San Pedro de Atacama in Chile (altitude 2500 m), and are developing very wideband receiver covering 210–375 GHz (corresponding to Bands 6–7 of ALMA) and full-automatic observation system. The new telescope system will provide large-scale data in the spatial and frequency domain of molecular clouds of Galactic plane and Large/Small Magellanic Clouds at the southern hemisphere. The data will be precious for the comparison with those of extra-galactic ones that will be obtained with ALMA as the Bands 6/7 are the most efficient frequency bands for the surveys in extra-galaxies for ALMA.
Owing to recent performance improvement and lower pricing of computers, built-in computers are equipped in virtually all measurement/control hardware, and small computers (e.g., Raspberry-Pi) can be obtained inexpensively to monitor the environment and/or hardware status. Those devices are able to communicate via network. The system having flexibility adaptable with the rapidly changing trend of hardware is desired in order to provide powerful functions quickly for the telescope control. Software developed for robot operations could be used for this purpose that controlling distributed and network-linked hardware. The Robot Operating System (ROS) is an open source software platform and one of the most used frameworks for robot operations. It has a number of libraries and tools to help us create robot applications. Under this background, we are developing NECST (NEw Control System for Telescope) using ROS framework. In NECST, each atomic operation (such as device operation and arithmetic operation) is divided into a node which is an elemental object in ROS. Nodes are grouped and packaged by their functionalities for convenience. The control systems of telescope and receiver are built by combining those packages. Since there are about ∼100 nodes even in the telescope control part, we also developed utilities to manage nodes that visualizes sent/received data in real time. Currently, NECST is installed and operated mainly for receiver control and antenna control of 1.85-m mm-submm wave telescope.
We are promoting the Hybrid Installation Project in Nobeyama, Triple-band Oriented (HINOTORI), a project aiming at triple-band simultaneous single-dish and VLBI observation in the 22-, 43- and 86-GHz bands using the Nobeyama 45-m Telescope. The triple-band simultaneous observation becomes possible by developing two perforated plates and mounting them in the Nobeyama 45-m Telescope optics. One is a 22/43-GHz-band perforated plate, which transmits the higher frequency (43-GHz) band and reflects the lower frequency (22-GHz) band, and the other is a 43/86-GHz-band perforated plate, which transmits the 86-GHz band and reflects the 43-GHz band or lower. Both plates are designed to be installed in the large telescope optics with a beam diameter as large as 50 cm and insertion/reflection losses are both 0.22 dB (5%) or less in the design. The receivers used in triple-band simultaneous observation system are the H22 and H40 receivers, which are already installed in the Nobeyama 45-m Telescope, and the TZ receiver, which is a 100-GHz-band receiver including the 86-GHz band and reinstalled in the Nobeyama 45-m Telescope. A system of simultaneous observations in the 22- and 43-GHz bands of the Nobeyama 45-m Telescope with the 22/43- GHz-band perforated plate has been completed and commissioned for scientific observations. Also VLBI fringes between the Nobeyama 45-m telescope with the dual-band observation system and the VERA 20-m telescopes at 22 and 43 GHz was detected successfully.
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