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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