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Amateur Astronomer Discovers Aten-Class Asteroid


http://cfa-www.harvard.edu/cfa/ps/pressreleases/1997MW1.html

PRESS INFORMATION SHEET:

1997 MW1 -- AMATEUR ASTRONOMER DISCOVERS ATEN-CLASS MINOR PLANET

Produced at the Harvard-Smithsonian Center for Astrophysics (CfA),
Cambridge, Massachusetts, U.S.A.

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An American amateur astronomer has discovered the latest addition to the
rare class of near-earth objects known as Atens.

Arizona astronomer Roy Tucker was observing fields in the Milky Way for his
HELIOS (High Ecliptic Latitude Interplanetary Object Search) program on June
28 when he detected a fast-moving object. He followed it up the next night,
then reported accurate measurements from both nights to the Minor Planet
Center (MPC). With a daily motion of about 1.1 degrees (for comparison, the
diameter of the moon is 0.5 degrees and main-belt minor planets will have
daily motions smaller than this) the object was clearly interesting, so it
was added to the Center's NEO Confirmation Page in the expectation that
other observers would confirm the object and obtain sufficient observations
to allow orbit computations.

Early attempts by other observers to confirm the object were not successful,
possibly because the object was fainter than expected on the basis of
Tucker's initial report. Tucker reported his third night of observation at
13:45 UT on July 1. The first follow-up observations by observers other than
the discoverer came from two Japanese observers around 16:00 UT that day.
The prediction on the Confirmation Page was updated, but it was felt that
there were not yet enough observations to announce the discovery on a Minor
Planet Electronic Circular (MPEC).

Over the next ten hours additional observations came from observers in the
Czech Republic, Australia, Italy and the U.S. By the morning of July 2 the
orbit computations was considered secure. The object was designated 1997 MW1
and an MPEC announcing the discovery was issued at 12:29 UT.

Aten-type minor planets have mean distances from the sun less than 1
astronomical unit (roughly the distance of the earth from the sun, 150
million km), but move out beyond the orbit of the earth when farthest from
the sun. Because Atens spend a lot of time close to the sun as seen from the
earth they are rather difficult to discover. The discovery of 1997 MW1
brings to 25 the number of known Atens and this is the first Aten to be
discovered by an amateur astronomer.

The orbit of 1997 MW1 is inclined at about 13° to the plane of the earth's
orbit. The distance from the sun varies from 91 million km (at perihelion)
to 189 million km (at aphelion) over the course of a 331-day orbit, but 1997
MW1 does not currently come within 15 million km of the earth. 1997 MW1 will
pass its aphelion point on July 9 and the object should be observable for a
few months, but it will fade quite rapidly. Although the diameter of 1997
MW1 is unknown, a possible range is 350 to 750 metres, depending on how much
light the surface reflects (if the surface is dark, the object's size will
be near the upper limit). 1997 MW1 is the second Aten discovered so far in
1997 and potentially the largest such object since October 1994.

It would appear that Tucker will be eligible to be the first recipient of
the recently-announced "Benson Prize for the Amateur Discovery of Near-Earth
Asteroids". It is worth emphasizing that Tucker's ability to produce
accurate astrometric positions for his discovery was vital in allowing the
object to be confirmed. Without accurate coordinates reported immediately,
the object could well have become lost.

Roy Tucker was born in Jackson, Mississipi, in 1951, grew up in Memphis,
Tennessee and currently lives in Tucson, Arizona. He gained a BS in Physics
in 1978 from Memphis State University and a MS in Scientific Instrumentation
in 1981 from the University of California, Santa Barbara. He is currently
chief electronics engineer for an optical metrology company in Tucson and
sole proprietor of Southwest Cryostatics, a company offering construction of
homebuilt charge-coupled device (CCD) detectors. His private observatory,
the Goodricke-Pigott Observatory, houses a 0.36-m Schmidt-Cassegrain
equipped with a CCD detector. The telescope's field-of-view is 0.2 degrees
and the faintest stars detectable (mag. 20.5) are 1/640000 as bright as the
faintest stars detectable by the unaided eye. 1997 MW1 is the first major
result of his HELIOS program, begun in May 1997, and was found after a total
of 28 hours of imaging and the examination of 83 pairs of images.

1997 July 2, updated July 3

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