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Study of source distribution of Jovian decameter radiation based on the long baseline interferometer observation

Research Project

Project/Area Number 16540407
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeSingle-year Grants
Section一般
Research Field Space and upper atmospheric physics
Research InstitutionFukui University of Technology

Principal Investigator

NAKAJO Tomoyuki  Fukui University of Technology, Space Communication Engineering, Lecturer (00367509)

Co-Investigator(Kenkyū-buntansha) OYA Hiroshi  Fukui University, Space Communication Engineering, Professor (80025931)
ONO Takayuki  Tohoku University, Department of Geophysics, Professor (10141996)
IIZIMA Masahide  Tohoku University, Department of Geophysics, Associate Professor (80232114)
Project Period (FY) 2004 – 2007
Project Status Completed (Fiscal Year 2007)
Budget Amount *help
¥3,290,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥90,000)
Fiscal Year 2007: ¥390,000 (Direct Cost: ¥300,000、Indirect Cost: ¥90,000)
Fiscal Year 2006: ¥300,000 (Direct Cost: ¥300,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2004: ¥1,500,000 (Direct Cost: ¥1,500,000)
KeywordsPlanetary radio emission / Jupiter / radio interferometer / decameter / digital receiver / space plasma / 干渉計 / 電波天文学 / 低周波 / 長距離干渉計 / 太陽 / 惑星 / DSP
Research Abstract

We have developed a VLBI (Very Long Baseline Interferometer) network for determining the location or structure of Jovian decameter radiation (JDR) sources. This study has been carried out in the collaboration between Fukui University of Technology and Tohoku University. The developed VLBI system consists of Awara station in Fukui, Iitate station in Fukushima, Zao and Yoneyama stations in Miyagi. The Maximum baseline length is 540km (Awara-Yoneyama baseline) whose spatial resolution is about 5 arcsec at observation frequency of 20 MHz.
It has been considered that the VLBI observation in decameter range is difficult because of the enormous influence of terrestrial ionosphere. To overcome this problem, the dual frequency technique has been tested by the group of Tohoku University from 1994 The one of the aims of this research is to evaluate the validity of the dual frequency technique based on 400km class VLBI observations.
The observation system installed in each observation station consis … More ts of five parts, i. e. front-end, main receiver data recording system ant some support equipments. The front-end consists of 9 elements log-periodic antenna whose detectable frequency range is from 20 MHz to 40 MHz and pre-amplifier. The pre-amplifier consists of a bandpass filter whose passband is ranging from 20 MHz to 40 MHz and the low noise wideband amplifier The received signals by the front-end are fed into the wideband main receiver which consists of two receiving system so that the dual frequency observation is made. The frequency system of this main receiver is controlled by the reference clock of cesium or rubidium beam oscillator which ensures the phase stability of the observation system. The output of the main receiver is directly digitized and stored in each observation station. The time synchronization between the observation stations is ensured by using 1PPS signals of GPS system.
The observation has been started in 2006, however we suffered from some troubles in the observation system In addition, the activity of JDR had been very low from 2006 to 2007. Therefore, the first light had come on March 28 in 2008. The received JDR event is categorized to Io-related radiation which is called “Io-B". The observation was carried out under the condition of high Signal to Noise ratio because of its strung intensity. The observation frequencies were set to 22 MHz and 22.5 MHz, however, the dual frequency analyses could not be carried out because of the narrow band characteristics of the JDR event. For considering the source structure of the received JDR event, we have carried out the closure phase analyses instead of the dual frequency analyses. In the closure phase analyses, the sum of phases detected by three baselines by which triangles can be made is calculated. The value of closure phase is decided only by the source structure and is free from the ionospheric effects and the instrumental errors. The closure phase value of the received JDR event takes zero with error of +/- degrees at the data points whose normalized cross correlation coefficients are over 0.4, which means the Signal to Noise ratio is over -4dB. This high accuracy can be achieved by the wideband character of the observation system This result shows that the source of observed JDR is compact enough to consider as single point.
In this study, it has been showed that the closure phase analyses are also useful for eliminating the ionospheric effects and the instrumental errors in the VLBI observation for decameter waves. For the future study, it is considered that more investigation is necessary for evaluating the validity of the closure phase and the dual frequency analyses as a method of eliminating the ionospheric effects on the VLBI observations. Less

Report

(5 results)
  • 2007 Annual Research Report   Final Research Report Summary
  • 2006 Annual Research Report
  • 2005 Annual Research Report
  • 2004 Annual Research Report
  • Research Products

    (20 results)

All 2008 2007 2006 2005 Other

All Journal Article (7 results) (of which Peer Reviewed: 2 results) Presentation (11 results) Remarks (2 results)

  • [Journal Article] 長距離基線干渉計による木星デカメータ電波源の位置決定法2008

    • Author(s)
      中城智之
    • Journal Title

      福井工業大学研究紀要 33

      Pages: 313-320

    • NAID

      110006979910

    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
    • Peer Reviewed
  • [Journal Article] Position Determination Method of Jovian Decametric Radiation Sources based on Very Long Baseline Interferometer Observation2008

    • Author(s)
      Tomoyuki Nakajo, Takayuki Ono, Masahide Iizima, Takuya Iwagawa, Hikaru Ito
    • Journal Title

      Memoirs of Fukui University of Technology 38

      Pages: 313-320

    • NAID

      110006979910

    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Journal Article] 木星デカメータ電波に対する遅延時間解析2007

    • Author(s)
      中城 智之
    • Journal Title

      第8回惑星圏研究会集録

    • Related Report
      2006 Annual Research Report
  • [Journal Article] 木星デカメータ電波を対象とする400km級長距離基線干渉計観測2006

    • Author(s)
      中城 智之
    • Journal Title

      第25回生存圏シンポジウム 第10回生存圏波動分科会講演予稿集

    • Related Report
      2005 Annual Research Report
  • [Journal Article] 400km級長距離基線干渉計による木星デカメータ電波観測2005

    • Author(s)
      中城 智之
    • Journal Title

      地球惑星科学関連学会2005年合同大会予稿集

    • Related Report
      2005 Annual Research Report
  • [Journal Article] 400km級長距離基線干渉計を用いた木星デカメータ電波観測システム開発と観測精度2005

    • Author(s)
      中城 智之
    • Journal Title

      第118回地球電磁気・地球惑星圏学会講演会 講演予稿集

    • Related Report
      2005 Annual Research Report
  • [Journal Article] 長距離基線干渉計による木星デカメータ電波源の位置決定法

    • Author(s)
      中城智之
    • Journal Title

      福井工業大学研究紀要 (印刷中)(掲載確定)

    • NAID

      110006979910

    • Related Report
      2007 Annual Research Report
    • Peer Reviewed
  • [Presentation] 超長距離基線干渉計による木星デカメータ電波源位置決定2008

    • Author(s)
      中城智之
    • Organizer
      第9回惑星圏研究会
    • Place of Presentation
      東北大学
    • Year and Date
      2008-03-20
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Annual Research Report 2007 Final Research Report Summary
  • [Presentation] Determination Method of Jovian Decametric Radiation Sources based on Very Long Baseline Interferometer Observation2008

    • Author(s)
      Tomoyuki Nakajo, Takayuki Ono, Masahide Iizima, Hiroshi Oya
    • Organizer
      9th PPARC Symposium on Planetary Atmospheres and Magnetospheres
    • Place of Presentation
      Sendai
    • Year and Date
      2008-03-08
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] 400km級長距離基線干渉計による木星デカメータ電波観測2007

    • Author(s)
      中城智之
    • Organizer
      第122回地球電磁気・地球惑星圏学会
    • Place of Presentation
      名古屋大学
    • Year and Date
      2007-10-01
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Annual Research Report 2007 Final Research Report Summary
  • [Presentation] 月-地球間木星電波VLBIに向けてのe-VLBI地球観測網による木星電波源の研究プロジェクト2007

    • Author(s)
      今井一雅
    • Organizer
      第122回地球電磁気・地球惑星圏学会
    • Place of Presentation
      名古屋大学
    • Year and Date
      2007-10-01
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] Observation results of Jovian decametric radiation by using a long baseline interferometer system2007

    • Author(s)
      Tomoyuki Nakajo, Takayuki Ono, Masahide Iizima, Hiroshi Oya
    • Organizer
      122 th SGEPPS fall meeting
    • Place of Presentation
      Nagoya
    • Year and Date
      2007-10-01
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] An e-VLBI Grobal network leading to moon-earth baseline VLBI observations of Jupiter's decametric radio source2007

    • Author(s)
      Kazumasa Imai, Tetsuro Kondo, Hiroaki Misawa, Fuminori suchiya, Tomoyuki Nakajo, Nobuyuki Kawano, Hirotomo Noda, Takahiro Iwata, Junpei Azuma, Masafumi Imai
    • Organizer
      122 th SGEPPS fall meeting
    • Place of Presentation
      Nagoya
    • Year and Date
      2007-10-01
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] 月一地球間木星電波 VLBI に向けての e-VLBI 地球観測網による木星電波源の研究プロジェクト2007

    • Author(s)
      今井一雅
    • Organizer
      第122回地球電磁気・地球惑星圏学会
    • Place of Presentation
      名古屋大学
    • Year and Date
      2007-10-01
    • Related Report
      2007 Annual Research Report
  • [Presentation] 長距離基線電波干渉計を用いた木星デカメータ電波観測2007

    • Author(s)
      中城智之
    • Organizer
      電気関係学会北陸支部連合大会
    • Place of Presentation
      福井工業大学
    • Year and Date
      2007-09-20
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Annual Research Report 2007 Final Research Report Summary
  • [Presentation] Observation of Jovian decametric radiation by using a long baseline Interferometer2007

    • Author(s)
      Tomoyuki Nakajo, Hiroshi Oya
    • Organizer
      Joint Conference of Hokuriku Chapters of Electrical Societies
    • Place of Presentation
      Fukui
    • Year and Date
      2007-09-20
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Presentation] 木星デカメータ電波に対する遅延時間解析2007

    • Author(s)
      中城智之
    • Organizer
      地球惑星科学関連学会2007年合同大会
    • Place of Presentation
      千葉、幕張メッセ
    • Year and Date
      2007-05-20
    • Description
      「研究成果報告書概要(和文)」より
    • Related Report
      2007 Annual Research Report 2007 Final Research Report Summary
  • [Presentation] Delay time analysis for determining the source structure of Jovian decametric radiation2007

    • Author(s)
      Tomoyuki Nakajo, Takayuki Ono, Masahide Iizima, Hiroshi Oya
    • Organizer
      Japan Geoscience Meeting
    • Place of Presentation
      Chiba
    • Year and Date
      2007-05-20
    • Description
      「研究成果報告書概要(欧文)」より
    • Related Report
      2007 Final Research Report Summary
  • [Remarks] 「研究成果報告書概要(和文)」より

    • URL

      http://www.fukui-ut.ac.jp/asro/project/jupiter-VLBI.htm

    • Related Report
      2007 Final Research Report Summary
  • [Remarks]

    • URL

      http://www.fukui-ut.ac.jp/asro/project/jupiter-VLBI.htm

    • Related Report
      2007 Annual Research Report

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Published: 2004-04-01   Modified: 2016-04-21  

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