Several asteroids with semimajor axes just above 2.82 AU were discovered during last ten years. However, their orbits are not determined precisely enough to numerically integrate their orbital evolution in the 5:2 region and determine lifetimes or memberships to the Koronis family.

Hence we are asking for astrometric observations especially of these asteroids: 1992 RF5, 1988 DX1 and 1989 TT3. Other asteroids involved in our calculations, which do not have large orbit uncertainities are (9631), (9990), 1992 DH3, 1988 RY5 and 1996 TE - their observations would be also appreciated, but they are not so critical.

designation | oposition | magnitude |

1992 RF5 | 20000402 | 17.3 |

1988 DX1 | 20001128 | 18.8 |

1989 TT3 | 20010111 | 19.4 |

1992 DH3 | 20010110 | 19.0 |

1988 RY5 | 20000823 | 16.4 |

1996 TE | 20000611 | 18.1 |

(9631) | 20000630 | 17.3 |

(9990) | 19991226 | 17.3 |

The table lists the asteroid number or its preliminary designation, the date of the next oposition (in YYYYMMDD format) and finally the approximate apparent magnitude during that oposition.

More informations about our reseach, numerical simulations and Yarkovsky effect could be found at our WEB site http://sirrah.troja.mff.cuni.cz/~mira/mp/

Miroslav Broz (mira@sirrah.troja.mff.cuni.cz) and
David Vokrouhlicky (vokrouhl@mbox.cesnet.cz)

Institute of Astronomy, Charles University, Prague, Czech Republic

Miroslav Broz, miroslav.broz@email.cz, Dec 22nd 1999