The dust-tube structure of the Leonid meteor shower 1998 based on a network of unaided counting observation

EPS Japan 1999,June (in Yoyogi)

Inoue S., Ogawa S.,(Misato Tech. High), Machimura H., Sugita A., Watanabe M., (Seikei High),Leonid 98 Project (2576 students).

We participated in the Leonid meteor observation network with naked eye for@senior-high school sutudents on Nov. 18@1998. The aim of observation was to seek to clarify the dust-tube structure which produced by the parent comet 55p/Tempel-Tuttle. The network comprised the 268 observation teams consisting of about 2600 senior-high school students. Each observation point was located about several tens of kilometer from the next points, and were scattered from Hokkaido to Okinawa. In order to research detail information of the dust-tube structure, the period of meteor counting is necessary for a 10 minute interval. Without the coastal range of the Japan Sea, the weather was almost fine, and over 250 groups carried out successful observation.

As a result of our observation, the maximum hourly rate with correction of radiation point altitude was about 100 counts/hour. This rate is the lower limit of predicted flux (Z. Wu, and I.P.Williams, 1996), and means that the average distance of meteoroids is roughly estimated as about 600 km. With this condition, over the Japanese islands, the apparent difference of hourly rate and/or peak time of meteor shower was not detected on the basis of the analyses using the selected data. The small peak time of shower (around 4h00m on Nov. 18 JST) was consistent with the predicted time when the earth would cross 55p/Tempel-Tuttle orbital plane. Consequently, the inhomogeneity within a 1000km scale was not clearly observed on the dust-tube of the comet.