NOTE BREVI DOI 10.1393/ncc/i2004-10034-x IL NUOVO CIMENTO Vol. 27 C, N. 4 Luglio-Agosto 2004 The orbit and evolution of the Geminid meteoroid stream V. Porubˇ can( 1 )( 2 ), L. Kornoˇ s( 1 ), G. Cevolani( 3 ) and G. Pupillo( 3 )( 4 )( 5 ) ( 1 ) Department of Astronomy, Physics of the Earth and Meteorology FMPI Comenius University - 842 48 Bratislava, Slovakia ( 2 ) Astronomical Institute of the Slovak Academy of Sciences - 845 04 Bratislava, Slovakia ( 3 ) CNR-ISAC - Via Gobetti 101, 40129 Bologna, Italy ( 4 ) DET, Universit` a di Firenze - 50139 Firenze, Italy ( 5 ) Osservatorio di Campi Salentina - 73012 Campi Salentina (Lecce), Italy (ricevuto l’11 Novembre 2004; approvato il 24 Novembre 2004) Summary. — The orbit and radiant of the Geminid meteoroid stream based on an analysis of the current version of the IAU MDC catalogue of photographic meteors are studied and discussed. The mean orbit, shape, size and ephemeris of the radiant are derived. The radiant area of the central part of the stream is more concentrated with the densest part of the size of 2 ◦ × 2 ◦ . The orbital evolution of the stream is investigated and compared with the evolution of its potential parent asteroid 3200 Phaethon. PACS 96.50.Kr – Meteors, meteoroids, and meteor streams. PACS 95.85.Bh – Radio, microwave (> 1 mm). PACS 96.30.Ys – Asteroids (minor planets). 1. – Introduction The Geminid meteor shower active for about two weeks in the beginning of December has been known since the second half of the 19th century [1]. The shower maximum with the visual peak rate of about 100 meteors per hour appears at the solar longitude of 262 ◦ . The Geminids rank among the most concentrated meteor showers with the activity corresponding to the half maximum rate lasting for about two-three days (December 12- 14). Among all the known regular meteoroid streams the Geminids move on the smallest and at the same time the best-defined orbit [2] with the period of revolution of only 1.6 years. After recognition that the stream may be associated with asteroid 3200 Phaethon by Whipple in 1983 [3], the shower is studied more intensively. The present paper presents a study of the radiant and orbit of the Geminid meteoroid stream based on the precise photographic orbits available from the current catalogue of the IAU Meteor Data Center—version 2003 [4] and analysis of the orbital evolution of the stream as well as of the asteriod 3200 Phaethon considered for its parent body. c  Societ` a Italiana di Fisica 395 brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by Scientific Open-access Literature Archive and Repository