2004 MC (Amor caught 12 days before close approach to Earth)
When discovered by LINEAR on 2004 June 16.1 UT this object was moving
relatively slowly SSE in Libra at about 1"/min and was placed on
the NEO confirmation page for further observations just after 15:00 UT
that day. H. Michels confirmed it just before 22:00 UT from Herrenberg
Observatory (MPC code 240). Although moving slowly it was apparently
accelerating at about 20% per day.
The Spanish comet and NEO observer Juan Lacruz (La
Cañada Observatory, MPC code J87, discoverer of Minor Planet 2003
SU224) was in the UK that week with his wife, by chance
staying just a few miles from Great Shefford and with a good clear sky
on the night of 16th June they were invited to visit and help
observe.
Although there were five objects listed on the NEO Confirmation page
that night all but one were either too faint or too far south to be
imaged from Great Shefford.
The remaining object was only at an altitude of 26° from the horizon
and listed as mag +18.7 and moving at just 1.06"/min. A set of 21
exposures were taken but initially could not be found within the
uncertainty area given by the Minor Planet Center. When the prediction
was refined later that night after the confirmation from Herrenberg the object
was located towards the edge of the images (see the animation above) and
positions were sent to the Minor Planet Center.
After four more observatories in California, Arizona and New
Mexico reported positions in the following few hours the object was
announced as 2004 MC on Minor Planet Circular MPEC
2004-M07 and this indicated that it was due at perihelion in early July
2004 and had a perihelion distance almost
exactly 1 AU from the Sun. Indeed the Minor Planet Center is listing
this as an Amor object defined strictly as having a perihelion distance
greater than 1.000 AU, but JPL are listing it as an Apollo, with
perihelion inside the Earth's orbit (q=1.0083 AU but the Earth being at aphelion
at ~1.016 AU from the Sun in July when the orbits of the two bodies are
closest to each other).
12 days after discovery on 2004 June 29.5 AU it was to pass less than four Lunar Distances
away from the Earth. At that time it would be deep in the Southern
skies, not visible from Great Shefford, but would have brightened to mag
+14.5 and be moving at about 70"/min. It was last reported on 30th
June by John Broughton from Reedy Creek (code 428) in Australia and in
the following days faded quickly as it receded from the Earth in the
morning sky.
During the observing session this picture was
taken and is used with permission of Juan Lacruz:
Left to right: Peter Birtwhistle, Covadonga Camblor Lacruz and Juan
Lacruz inside the observatory at Great Shefford.
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