MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov
Contact: Martha J. Heil (818) 354-0850
FOR IMMEDIATE RELEASE
November 17, 2000
TWINKLE, TWINKLE, LITTLE ASTEROID
Stars twinkle, but usually not like this! On the morning of
Nov. 20, asteroid 752 Sulamitis will be seen, from some places on
Earth, passing in front of a star in the constellation Gemini,
making the star fade away for up to 10 seconds. This will be
long enough for amateur astronomers with home video cameras to
contribute valuable information to studies on the size and shape
of the asteroid.
Not much is known right now about 752 Sulamitis, except that
it may be up to 105 kilometers (65 miles) in diameter. The path
of this stellar eclipse may cut across the upper eastern half of
the United States. "Being able to see an asteroid pass in front
of, or occult, a star is rare," said Lance Benner, an expert on
asteroids at NASA's Jet Propulsion Laboratory, Pasadena, Calif.,
and a member of the International Occultation Timing Association
(IOTA).
This is the first time an asteroid occulting a star can be
seen in North America since 1975, when such predictions became
readily available. The star, known as Tejat, is bright enough to
be seen with the naked eye. The asteroid is very faint -- about
18,000 times fainter than the star, and cannot be seen without a
telescope.
The region where the eclipse is visible will be a narrow
band slanting from North Carolina's coast northwest to Madison,
Wis., to northern Alaska. Residents of Chicago, Minneapolis,
Indianapolis and Cincinnati may also be able to see the asteroid
as it fades out for about two seconds. The asteroid's path may be
about 78 kilometers (48 miles) to the right or the left of the
route drawn on the map.
The star, which is located in the southern corner in the
constellation Gemini (just above Orion), will be intersected by
the asteroid from 6:41 to 6:49 a.m. Eastern time. It will take
eight minutes to move from the East Coast to the north boundary
of the continental United States. Star-watchers can set up their
cameras and telescopes, mark their location, and tune in to
short-wave radio station WWV, Boulder, Colo. at 2.5, 5, 10, 15,
20 megahertz. By coordinating with the station's time signal,
observers can mark when they see the star, which will be just
one-third of the moon's brightness, disappear and reappear as the
asteroid blocks it from view. The occultation will be unlike the
normal twinkling of the star caused by Earth's atmosphere,
because it will take about three seconds to fade out, remain
obscured from view for 10 seconds and fade back in 3 seconds.
Observations of the shadow across the star can be reported
to the International Occultation Timing Association. An analysis
of the observations will help define the asteroid's shape and
size. Reports from those who observe the star but don't see it
disappear are still scientifically useful -- they can help
determine the size of the asteroid and the precise location of
the asteroid's track across the United States. And observers in
outlying areas may see only a partial eclipse of the red
supergiant star, since it doesn't have a sharp outline like
younger stars.
Observations can be reported to the IOTA, online at
http://www.lunar-occultations.com/iota/iotandx.htm. JPL is
managed by the California Institute of Technology for NASA. For
more information, and a partial map of viewing locations, see
www.jpl.nasa.gov.
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11/17/00 MJH
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