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The Dionysus Occultation Page
June 17, 1997
3671 DIONYSUS: ASTEROID WITH A MOONLET?
The Apollo-type asteroid 3671 Dionysus, an Earth-crosser in a 3.25 year orbit,
is having a close approach of about 17 million km of Earth in July, when it
will brighten to 15th magnitude. When Stefano Motola and Gerhard Hahn of
DLR - Institute of Planetary Exploration, Berlin observed its rotational
light curve earlier this month, they noticed a brightness change of 0.08
evrey 1.15 days. So probably Dionysus has a companion, and we are now
looking right along its orbital plane.
Dionysus would not be the only asteroid with a small moonlet. Four years ago
the Galileo spacecraft discovered thay asteroid 243 Ida is orbited by a
small moonlet, which was later named Dactyl.
A good photometric coverage is needed to determine the dynamical properties
of the probable Dionysus asteroid/satellite system. Mottola and Hahn inivite
interested observers that have access to suitable instrumentation to follow
Dionysus and perform accurate, time-resolved photometry of this object. Predictions
fot expected occultation events can be found on their home page.
June 10, 1997
POSSIBLE SATELLITE FOUND ORBITING ASTEROID 3671 DIONYSUS
According the IAU Circular 6680, astronomers S. Mottola, G. Hahn, P. Pravec
and L. Sarounova using the European Southern Observatory in Chile may have
discovered a satellite orbiting the asteroid 3671 Dionysus. Based on
observations made from May 30 to June 8, attenutations in the asteroid's
brightness were noted, and a period of 1.155 days was derived from these
observations. They interpreted these features as occultations/eclipses of a
satellite orbiting the asteroid. Observers are encouraged to participate in
a monitoring campaign available at:
Asteroid 3671 Dionysus was discovered by Eugene and Carolyn Shoemaker
on May 27, 1984 at the Palomar Observatory. The asteroid was named
after the Greek God of vegetation, wine and pleasure.
It is an Apollo asteroid and its orbit overlaps the
Earth's orbit. Asteroid 3671 Dionysus will make make a close
flyby of Earth on July 6 of this year at a distance of 0.1144 AU (10.6
million miles or 17.2 million km) with a expected magnitude of 14.9.
Oribital elements and ephemeris of Asteroid 3671 Dionysus are available
at the Minor Planet Center operated by the Smithosian Astrophysical
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