31 108 33 34 兵庫県立大学 西はりま天文台 : 研究者向け
平成6年度（第5号）

論文リスト：

M67とNGC 7790のCCD測光観測、 pp1-10
　著者：中野仁1、小野智子2、志岐成友3、佐藤公彦4、石田俊人2、山岡 均1
　所属：1) 九州大学理学部、2) 兵庫県立西はりま天文台公園、3) 東京大学理学系研究科、4) 九州大学大学院総合理工学研究科
　著者の電子メイルアドレス: nakano＠gemini.rc.kyushu-u.ac.jp
　Received: 1995, June 28

概要： BVR CCD photometry of the open cluster M67 and NGC 7790 has been performed using 60-cm reflector at Nishi-Harima Astronomical Observatory (NHAO) on Oct. 2 and Dec. 15, 1994. Color equations are obtained for each observation, and compared with those which are obtained by Iyeshima, et al. (1994, Annu. Rep. Nishi-Harima Astron. Obs., 4, 8). For M67 the residuals of V magnitudes with the standard stars provided by Gilliland, et al. (1991, AJ, 101, 541) are also discussed. Moreover the color-magnitude diagram (CMD) for 49 stars in M67 is drawn up with the obtained color equations.

　キーワード：CCD Photometry -- Open Cluster: individual (NGC 7790, M67)
　電子版を入手： PDF (3.5MB)

兵庫県南部地震と関連する電波放射、 pp11-19
　著者：前田耕一郎1、時政典孝2、黒田武彦2
　所属：1) 兵庫医科大学、2) 兵庫県立西はりま天文台公園
　著者の電子メイルアドレス: maeda＠hyogomc.kugi.kyoto-u.ac.jp
　Received: 1995, July 12

概要： 1995年1月17日に兵庫県南部地震（マグニチュード=7.2）が発生した。我々は西はりま天文台において、電波干渉計により22.2MHz（波長=13.5m）で、この地震と関連して発生したと考えられる電波を受信した。パルス状の電波放射が本震発生時刻前後に受信されており、放射パルスの時間間隔は1〜3分の程度であった。また、干渉計のデータより放射の発生場所について検討した結果、破壊が地表にまで達した野島断層の中央部である可能性が高いとの結論を得た。これまでにも地震と関連すると思われる電波放射の観測例が報告されているが、今回のように、地震の断層破壊と直接に結び付く電波放射が観測されたのは初めてである。

　キーワード：Earthquake -- Radio Emission -- Fault Rupture
　電子版を入手： PDF (4.0MB)

A Report on Observations of Jovian Decametric Radiation during the SL9/Jupiter Impact Period、 pp20-34
　著者：Koichiro MAEDA1、Noritaka TOKIMASA2、Takehiko KURODA2
　所属：1) Hyogo College of Medicine、2) Nishi-Harima Astronomical Observatory
　著者の電子メイルアドレス: maeda＠hyogomc.kugi.kyoto-u.ac.jp
　Received: 1995, July 12

概要： Many fragments of the Shoemaker-Levy 9 comet (SL9) collided with Jupiter from July 16 through July 22 in 1994. During the SL9/Jupiter impact period we monitored the Jovian decametric emission activity at Nishi-Harima Astronomical Observatory, paying attention to each of the observable fragment impacts (fragments C, D, G, K, N, and W). To reliably identify Jovian radiation we made observations with a phase-switched interferometer having a baseline of 193m, a polarimeter, and two radiometers, In addition, dynamic spectrum observations were also made using an array consisting of 4 conical log-spiral antennas. We identified no Jovian decametric emission that was definitely related to any of the fragment impacts, although Jupiter-like narrow band radiation was observed at about 22.2 MHz about 30 min prior to the impact of fragment G on July 18. We identified an Io-related B (Io-B) storm just after the impact of fragment C on July 17. The characteristics of this Io-B storm were not different from those of a normal Io-B storm. We conclude that the SL9 collision with Jupiter had no significant effect on the Jovian decametric emission activity.

　キーワード：Jupiter -- Decametric emission: Commet collision
　電子版を入手： PDF (6.8MB)

西はりま天文台における低周波電波観測：ダイナミックスペクトラムの観測、 pp35-43
　著者：時政典孝1、前田耕一郎2
　所属：1) 兵庫県立西はりま天文台公園、2) 兵庫医科大学
　著者の電子メイルアドレス: tokimasa＠nhao.jp
　Received: 1995, November 17

概要： Low frequency radio astronomy observations at Nishi-Harima Astronomical Observatory (NHAO) started in 1992. We report a dynamic spectrum observation system which was recently completed at NHAO. An array consisting of four conical log-spiral antennas is used for observations in a frequency range 18 - 36 MHz, and commercial log periodic antenna for those in a frequency range 15 - 1300 MHz. A commercial spectrum analyzer, a kind of spectrograph, is used to obtain a frequency spectrum of the signal from the antenna. The frequency scan of the spectrum analyzer is normally done every 1 sec. The scan data are digitized using an analog-digital converter controll by a personal computer and stored on a hard disk. The dynamic spectrum is simultaneously displayed on a CRT monitor using the digitized data. We can more easily identify emissions in natural origin by the dynamic spectrum observations.

　キーワード：Radio Observation -- Dynamic Spectrum
　電子版を入手： PDF (3.9MB)

太陽活動サイクル22の期間内のフレア発生頻度、 pp44-64
　著者：久保田諄1、當村一朗2、時政典孝3
　所属：1) 大阪経済大学、2) 大阪府立工業高等専門学校、3) 兵庫県立西はりま天文台公園
　著者の電子メイルアドレス: tokimasa＠nhao.jp
　Received: 1995, December 12

概要： The time series of the daily rate for the occurence of Hα and soft X-ray flares during the activity cycle 22 was analyzed. The 210 days periodicity in the northernhemisphere was most significant, while the 155 days periodicity, which was remarkable during the cycle 20 and 21, was mirror in the cycle 22.

　キーワード：Solar activity -- flare -- sunspot
　電子版を入手： PDF (6.9MB)