Dr. Nobuharu Ukita Profile

Dr. Nobuharu Ukita

at National Astronomical Observatory of Japan

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Author

Publications (11)

Proceedings Article | 8 August 2016 Paper

Remote observing environment using a KVM-over-IP for the OAO 188 cm telescope

Kenshi Yanagisawa, Goki Inoue, Daisuke Kuroda, Nobuharu Ukita, Yoshihiko Mizumoto, Hideyuki Izumiura

Proceedings Volume 9913, 991330 (2016) https://doi.org/10.1117/12.2233815

KEYWORDS: Telescopes, Observatories, Astronomy, Domes, Switches, Video, Safety, Information security, Network security, Astronomical telescopes

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Proceedings Article | 28 July 2010 Paper

Wind-induced pointing errors and surface deformation of a 10-m submillimeter antenna

Nobuharu Ukita, Hajime Ezawa, Sachiko Onodera, Masao Saito

Proceedings Volume 7733, 77331D (2010) https://doi.org/10.1117/12.857279

KEYWORDS: Antennas, Reflectors, Computer programming, Telescopes, Servomechanisms, Turbulence, Sensors, Motion measurement, Wind measurement, Reflector telescopes

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Proceedings Article | 25 July 2008 Paper

HiCIAO: the Subaru Telescope's new high-contrast coronographic imager for adaptive optics

Klaus Hodapp, Ryuji Suzuki, Motohide Tamura, Lyu Abe, Hiroshi Suto, Ryo Kandori, Junichi Morino, Tetsuo Nishimura, Hideki Takami, Olivier Guyon, Shane Jacobson, Vern Stahlberger, Hubert Yamada, Richard Shelton, Jun Hashimoto, Alexander Tavrov, Jun Nishikawa, Nobuharu Ukita, Hideyuki Izumiura, Masahiko Hayashi, Tadashi Nakajima, Toru Yamada, Tomonori Usuda

Proceedings Volume 7014, 701419 (2008) https://doi.org/10.1117/12.788088

KEYWORDS: Adaptive optics, Telescopes, Imaging systems, Optical filters, Infrared cameras, Methane, Absorption, Sensors, Prisms, Image filtering

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Proceedings Article | 17 July 2008 Paper

Wind induced surface deformation of the Nobeyama 45-m radio telescope

N. Ukita

Proceedings Volume 7012, 70120V (2008) https://doi.org/10.1117/12.787910

KEYWORDS: Telescopes, Light emitting diodes, Wind measurement, Reflectors, Antennas, Lamps, Radio telescopes, CCD cameras, Finite element methods, Imaging systems

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Proceedings Article | 28 June 2006 Paper

Concept and science of HiCIAO: high contrast instrument for the Subaru next generation adaptive optics

Motohide Tamura, Klaus Hodapp, Hideki Takami, Lyu Abe, Hiroshi Suto, Olivier Guyon, Shane Jacobson, Ryo Kandori, Jun-Ichi Morino, Naoshi Murakami, Vern Stahlberger, Ryuji Suzuki, Alexander Tavrov, Hubert Yamada, Jun Nishikawa, Nobuharu Ukita, Jun Hashimoto, Hideyuki Izumiura, Masahiko Hayashi, Tadashi Nakajima, Tetsuo Nishimura

Proceedings Volume 6269, 62690V (2006) https://doi.org/10.1117/12.670742

KEYWORDS: Coronagraphy, Adaptive optics, Stars, Telescopes, Exoplanets, Polarization, Astronomy, Optical filters, Space telescopes, Actuators

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Proceedings Article | 23 June 2006 Paper

Vortex shedding from a 12-m antenna

Nobuharu Ukita, Masao Saito, Bungo Ikenoue, Jeffrey Mangum, Nicholas Emerson, Angel Otarola, Stefano Stangellini

Proceedings Volume 6267, 62673P (2006) https://doi.org/10.1117/12.670755

KEYWORDS: Antennas, Motion measurement, Turbulence, Computer programming, Reflectors, Wind measurement, Prototyping, Velocity measurements, Ultrasonics, Telescopes

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Proceedings Article | 28 September 2004 Paper

Design and performance of the ALMA-J prototype antenna

Nobuharu Ukita, Masao Saito, Hajime Ezawa, Bungo Ikenoue, Hideharu Ishizaki, Hiroyuki Iwashita, Nobuyuki Yamaguchi, Takahiro Hayakawa

Proceedings Volume 5489, (2004) https://doi.org/10.1117/12.551523

KEYWORDS: Antennas, Computer programming, Reflectors, Holography, Observatories, Prototyping, Stars, Servomechanisms, Metrology, Telescopes

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The National Astronomical Observatory of Japan has constructed a prototype 12-m antenna of the Atacama Compact Array to evaluate its performance at the ALMA Test Facility in the NRAO VLA observatory in New Mexico, the United States. The antenna has a CFRP tube backup structure (BUS) with CFRP boards to support 205 machined Aluminum surface panels. Their accuracies were measured to be 5.9 m rms on average. A chemical treatment technique of the surface panels has successfully applied to scatter the solar radiation, which resulted in a subreflector temperature increase of about 25 degrees relative to ambient temperature during direct solar observations. Holography measurements and panel adjustments led to a final surface accuracy of 20 m rms, (weighted by 12dB edge taper), after three rounds of the panel adjustments. Based on a long term temperature monitoring of the BUS and thermal deformation FEM calculation, the BUS thermal deformation was estimated to be less than 3.1 m rms. We have employed gear drive mechanism both for a fast position switching capability and for smooth drive at low velocities. Servo errors measured with angle encoders were found to be less than 0.1 arcseconds rms at rotational velocities below 0.1 degrees s-1 and to increase to 0.7 arcseconds rms at the maximum speed of the 'on-the-fly' scan as a single dish, 0.5 deg s-1 induced by the irregularity of individual gear tooth profiles. Simultaneous measurements of the antenna motion with the angle encoders and seismic accelerometers mounted at the primary reflector mirror edges and at the subreflector showed the same amplitude and phase of oscillation, indicating that they are rigid, suggesting that it is possible to estimate where the antenna is actually pointing from the encoder readout. Continuous tracking measurements of Polaris during day and night have revealed a large pointing drift due to thermal distortion of the yoke structure. We have applied retrospective thermal corrections to tracking data for two hours, with a preliminary thermal deformation model of the yoke, and have found the tracking accuracy improved to be 0.1 - 0.3 arcseconds rms for a 15-munites period. The whole sky absolute pointing error under no wind and during night was measured to be 1.17 arcseconds rms. We need to make both an elaborated modeling of thermal deformation of the structure and systematic searches for significant correlation among pointing errors and metrology sensor outputs to achieve the stable tracking performance requested by ALMA.

Proceedings Article | 3 July 2000 Paper

Development of the reflector panel for the new 10-m millimeter/submillimeter telescope

Hajime Ezawa, Masato Ishiguro, Hiroshi Matsuo, Keizo Miyawaki, Naohisa Satou, Nobuharu Ukita

Proceedings Volume 4015, (2000) https://doi.org/10.1117/12.390444

KEYWORDS: Reflectors, Telescopes, Reflector telescopes, Scattering, Antennas, Reflectivity, Aluminum, Extremely high frequency, Light scattering, Observatories

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Proceedings Article | 3 July 2000 Paper

Measurements of dynamic pointing variations of a large radio telescope

David Smith, Timothy Paglione, Amy Lovell, Nobuharu Ukita, Hiroshi Matsuo

Proceedings Volume 4015, (2000) https://doi.org/10.1117/12.390440

KEYWORDS: Antennas, Telescopes, Radio telescopes, Receivers, Mirrors, Calibration, Laser metrology, Optical instrument design, Observatories, Laser systems engineering

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Proceedings Article | 3 July 2000 Paper

NRO 10-m submillimeter telescope

Nobuharu Ukita, Ryohei Kawabe, Masato Ishiguro, Hajime Ezawa, Yutaro Sekimoto, Tatsuo Hasegawa, Satoshi Yamamoto, Keizo Miyawaki, Soichi Matsumoto

Proceedings Volume 4015, (2000) https://doi.org/10.1117/12.390409

KEYWORDS: Antennas, Telescopes, Computer programming, Submillimeter telescopes, Temperature metrology, Control systems design, Receivers, Observatories, Optical telescopes, Thermal effects

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Proceedings Article | 3 July 2000 Paper

BEARS: SIS 25-beam array receiver system for the NRO 45-m telescope

Kazuyoshi Sunada, Chieko Yamaguchi, Naomasa Nakai, Kazuo Sorai, Sachiko Okumura, Nobuharu Ukita

Proceedings Volume 4015, (2000) https://doi.org/10.1117/12.390416

KEYWORDS: Receivers, Spectrometers, Telescopes, Optical amplifiers, Staring arrays, Stars, Control systems, Attenuators, Fiber amplifiers, Switching

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Showing 5 of 11 publications

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