Journal ArticleDOI
Gigabit Digital Filter Bank: Digital Backend Subsystem in the VERA Data-Acquisition System
TLDR
The Gigabit Digital Filter Bank (GDFB) as discussed by the authors was developed for the VERA project, which is a project to construct a new Japanese VLBI array dedicated to make a 3D map of our Milky Way Galaxy in terms of high precision astrometry.Abstract:
The VERA terminal is a new data-acquisition system developed for the VERA project, which is a project to construct a new Japanese VLBI array dedicated to make a 3-D map of our Milky Way Galaxy in terms of highprecision astrometry. New technology, a gigabit digital filter, was introduced in the development. The importance and advantages of a digital filter for radio astronomy have been studied as follows: (1) the digital filter can realize a variety of observation modes and maintain compatibility with different data-acquisition systems (Kiuchi et al. 1997 and Iguchi et al. 2000a), (2) the folding noise occurring in the sampling process can be reduced by combination with a higher-order sampling technique (Iguchi, Kawaguchi 2002), (3) and an ideal sharp cut-off bandedge and a flat amplitude/phase responses are approached by using a large number of taps available to use LSI of a large number of logic cells (Iguchi et al. 2000a). We developed the custom Finite Impulse Response filter chips and manufactured the Gigabit Digital Filter Banks (GDFBs) as a digital backend subsystem in the VERA terminal. In this paper, the design and development of the GDFB are presented in detail, and the performances and demonstrations of the developed GDFB are shown.read more
Citations
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Journal ArticleDOI
Vertical Structure and Kinematics of the Galactic Outer Disk
Nobuyuki Sakai,Takumi Nagayama,Hiroyuki Nakanishi,Nagito Koide,Tomoharu Kurayama,Natsuko Izumi,Tomoya Hirota,Toshihiro Yoshida,Katsunori M. Shibata,Mareki Honma +9 more
TL;DR: In this article, the authors report measurements of parallax and proper motion for four 22 GHz water maser sources as part of VERA Outer Rotation Curve project, and indicate the signature of the warp to 600 pc toward the north Galactic pole.
Journal ArticleDOI
Performance of VERA in 10 micro-arcsecond astrometry
Takumi Nagayama,Hideyuki Kobayashi,Tomoya Hirota,Mareki Honma,Takaaki Jike,Mi Kyoung Kim,Akiharu Nakagawa,Toshihiro Omodaka,Tomoaki Oyama,Daisuke Sakai,Katsunori M. Shibata,Yoshiaki Tamura +11 more
TL;DR: In this paper, the authors evaluated the performance of the VLBI Exploration of Radio Astrometry (VERA) through the parallax measurements of five distant star-forming regions under good observing conditions of close separations and high elevations.
Journal ArticleDOI
Bow shocks in a newly discovered maser source in IRAS 20231+3440
TL;DR: In this paper, the authors measured the absolute proper motions of all the newly detected maser spots (30 spots) and presented two pictures describing the possible spatial distribution of the water maser as the morphology marks out an arc of masers whose average proper motion velocity in the jet direction was 14.26 km s$^{-1}$.
Journal ArticleDOI
Distance to the Low-velocity Cloud in the Direction of the High-velocity Compact Cloud CO–0.40–0.22
TL;DR: In this article, the authors performed phase-referencing very long baseline interferometry (VLBI) astrometry with VERA and detected the annual parallax of the H2O maser spot in the low-velocity cloud to be 0.33 ± 0.14 mas, which corresponds to a distance of from the Sun.
Journal Article
New VLBI Observing System 'OCTAVE-Family' to Support VDIF Specifications with 10 GigE for VERA, JVN, and Japanese e-VLBI (OCTAVE)
Tomoaki Oyama,Yusuke Kono,Syunsaku Suzuki,Shota Mizuno,Takeshi Bushimata,Takaaki Jike,Noriyuki Kawaguchi,Hideyuki Kobayashi,Moritaka Kimura +8 more
TL;DR: The new VLBI observing system (OCTAVE-Family) has been designed and developed based on the VSI-H and VDIF specications at NAOJ (National Astronomical Observatory of Japan) and is connected via 10 GigE network with VD IF and VSI specications.
References
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Book
Interferometry and Synthesis in Radio Astronomy
TL;DR: In this paper, a theory of interferometry and synthesis imaging analysis of the Interferometer Response Geometric Relationships and Polarimetry Antennas and Arrays Response of the receiving system Design of the Analog Receiving System Digital Signal Processing Very-Long-Baseline Interferometry Calibration and Fourier Transformation of Visibility Data Deconvolution, Adaptive Calibrration, and Applications Interferometers Techniques for Astrometry and Geodesy Propagation Effects Van Cittert-Zernike Theorem, Spatial Coherence, and
Journal ArticleDOI
Orbital motion in the radio galaxy 3C 66B: evidence for a supermassive black hole binary.
TL;DR: Using the very-long-baseline interferometer, it is found that the unresolved radio core of 3C 66B shows well-defined elliptical motions with a period of 1.05 ± 0.03 years, which provides a direct detection of a supermassive black hole binary.
Proceedings ArticleDOI
Digital Spectrometers for the Nobeyama 45-m Telescope
Kazuo Sorai,Kazuyoshi Sunada,Sachiko K. Okumura,Iwasa Tetsuro,Atsushi Tanaka,Kazuhito Natori,Hirofumi Onuki +6 more
TL;DR: In this paper, a commercial digital oscilloscope is used as a digitizer for the 25-BEam Array Receiver System (BEARS) of the Nobeyama 45m telescope.
Proceedings ArticleDOI
BEARS. SIS 25-BEam Array Receiver System for the NRO 45-m Telescope.
Kazuyoshi Sunada,Chieko Yamaguchi,Naomasa Nakai,Kazuo Sorai,Sachiko K. Okumura,Nobuharu Ukita +5 more
TL;DR: In this article, the SIS 25-BEam Array Receiver System (BEARS) is described, which is a large focal plane array receiver system for the NRO 45 m telescope.
Journal ArticleDOI
First Fringe Detection with VERA's Dual-Beam System and Its Phase-Referencing Capability
Mareki Honma,T. Fujii,Tomoya Hirota,K. Horiai,Kenzaburo Iwadate,Takaaki Jike,Osamu Kameya,Ryuichi Kamohara,Yukitoshi Kan-ya,Noriyuki Kawaguchi,Hideyuki Kobayashi,Seisuke Kuji,Tomoharu Kurayama,Seiji Manabe,Takeshi Miyaji,Kouichirou Nakashima,Toshihiro Omodaka,Tomoaki Oyama,Satoshi Sakai,Sei-ichiro Sakakibara,Katsuhisa Sato,Tetsuo Sasao,Katsunori M. Shibata,Rie Shimizu,Hiroshi Suda,Yoshiaki Tamura,Hideki Ujihara,Akane Yoshimura +27 more
TL;DR: In this paper, the results of the first dual-beam observations with VERA (VLBI Exploration of Radio Astrometry) were presented, and the results demonstrate the high capability of phase referencing, indicating that it is a promising tool for phase-referencing VLBI astrometry at 10 µas-level accuracy.
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