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Sky & Telescope Magazine
Above: A pair of the discovery images of the long-lost
satellite of Jupiter. The false-color pictures were taken
with the University of Hawaii's 2.2-meter telescope atop
Mauna Kea on the night of November 20-21. Courtesy Institute
for Astronomy, University of Hawaii.
In 1975,
Charles Kowal noticed a faint blip moving near Jupiter in
photographs taken with the 48-inch Schmidt telescope atop
Palomar Mountain. Presumed to be a new Jovian satellite,
the object was spotted a few weeks later by Elizabeth Roemer
observing at Kitt Peak. Then the putative moon was lost.
Fast-forward
to November 20, 2000: Scott S. Sheppard and his colleagues
at the University of Hawaii's Institute for Astronomy record
a faint moving object near Jupiter using a 2.2-meter reflector
atop Mauna Kea. They made additional observations during
the next several days and reported the object's precise
positions to the International Astronomical Union's Minor
Planet Center. According to an IAU Circular sent November
25th, the object was about to be designated S/2000 J 1 --
until additional calculations by Gareth V. Williams (Harvard-Smithsonian
Center for Astrophysics) linked the object back to Kowal's
quarter-century-old discovery. Consequently, the designation
of the object became S/1975 J 1. Sheppard and his colleagues
estimate that the moon is only 15 kilometers wide. It orbits
Jupiter in every 129 days at a distance of about 740,000
km.
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