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University of British Columbia Press Release

EMBARGOED UNTIL TUESDAY, JUNE 3, 8:00 A.M. PST 

CANADIAN ASTRONOMERS FIND NEW MOONS OF JUPITER

Part 1 of 2

DISCOVERY BOOSTS NUMBER OF JUPITER'S
KNOWN SATELLITES TO A RECORD 61

University of British Columbia Press Release

They were small and hard to find, but with the help of some new
telescopic equipment and cameras, UBC professor Brett Gladman,
UBC postdoctoral researcher Lynne Allen, and Dr. J.J. Kavelaars of
the National Research Council of Canada have discovered nine
previously unknown moons of Jupiter. So far this year, 21 new Jupiter
moons have been identified. 

The discovery of the distant satellites, announced today at the
annual meeting of the Canadian Astronomical Society, boosts the
number of known moons on Jupiter to 61 - more moons than any other
planet in the solar system.

"The discovery of these small satellites is going to help us
understand how Jupiter and the other giant planets formed," said
Gladman. 

The new satellites were a challenge to detect because most are only
about 1-5 kilometers in size. The feeble amounts of light they
reflect back to earth must compete against the glare of brilliant
Jupiter. Their small size and distance from the Sun prevent the
satellites from shining any brighter than 24th magnitude, about 100
million times fainter than can be seen with the unaided eye. To
locate these new moons, Gladman's team used the new Megaprime mosaic
of CCD cameras at the 3.6m Canada-France-Hawaii telescope on Mauna
Kea, Hawaii. 

The mosaic camera enabled the team to take three images of the
entire sky around Jupiter. They used computer algorithms to search
the images for the faint points of light moving across the sky as
moons should.

Because moons can sometimes appear in front of distant stars or lost
in the light scattered from the planet, to find them requires
painstakingly repeating the search several times. The team undertook
the task between February and April 2003. 

International members of the jovian search team include Cornell
University astronomers Phil Nicholson, Joseph A. Burns, and Valerio
Carruba, Jean-Marc Petit of the Observatoire de Besancon, and Brian
Marsden and Matthew Holman of the Harvard-Smithsonian Center
for Astrophysics. 

For more information on the discovery visit Prof. Gladman's Web site
at http://www.astro.ubc.ca/people/gladman/jup2003.html

To arrange an interview with Prof. Gladman or other members of the
discovery team, contact Michelle Cook, UBC Public Affairs Office at
604.822.2048. 

=====================================================================

Irregular Satellites of Jupiter

EMBARGOED UNTIL Tuesday JUNE 3, 2003, 1:00 AM Pacific time.

So far this year, Jupiter has gained 21 new distant satellites, with
the most recent announcement of satellite S/2003 J 21 (discovery
announcement from Minor Planet center here) on June 3rd at the annual
Canadian Astronomical Society meeting. This puts Jupiter far ahead of
the all other planets, with 61 known moons. Astronomers from the
University of British Columbia (Professor Brett Gladman and
postdoctoral researcher Lynne Allen) and the National Research
Council (Dr. JJ Kavelaars) of the National Research Council of Canada
are the discovery team. 

The work has been made possible by the new Megaprime mosaic of CCD
cameras at the 3.6m Canada-France-Hawaii telescope.

Information on the discoveries, the tracking effort, and new results
are provided below.

Sifting the Sand at Jupiter

Astronomers in Canada have been busy the last few months peering
around the planet Jupiter to search for small new moons of that
planet, extending a spree of moon discoveries begun in 1997. The
current team of jovian searchers consists of UBC astronomers Brett
Gladman and Lynne Allen, and JJ Kavelaars of the National Research
Council of Canada. The international team includes Cornell University
astronomers Phil Nicholson, Joseph A. Burns, and Valerio Carruba,
Jean-Marc Petit of the Observatoire de Besancon, and Brian Marsden
and Matthew Holman of the Harvard-Smithsonian Center for
Astrophysics.

Detecting satellites around gigantic Jupiter is a difficult
undertaking because they can occupy a large patch of sky around the
planet (making searching time consuming) and the feeble amounts of
light they reflect back to us must compete against the glare of
brilliant Jupiter. New and bigger detectors have made more complete
searches possible, and twenty one new jovian satellites have been
discovered this year. 

This boosts the number of known satellites of jupiter to sixty one.
It now appears that each giant planet's irregular satellite
population is the result of ancient collisions between former moon
and passing comets or asteroids. "These collisions result in the
production of families of satellites in similar orbits," said
Gladman, "which seem to be the rule". 

NEEDLE IN A HAYSTACK

The new satellites were a challenge to detect because most are only
about 1-5 kilometers in size. Their small size and distance from the
Sun prevent the satellites from shining any brighter than 24th
magnitude, about 100 million times fainter than can be seen with the
unaided eye. To locate these new moons, the canadian team has been
using the brand new Megaprime mosaic of CCD cameras at the 3.6m
Canada-France-Hawaii telescope on Mauna Kea in Hawaii. Covering all
the sky in which satellites could be found required this new large
mosaic camera, enabling them to quickly obtain images of the entire
sky around the planet in which the moons could be living. They used
computer algorithms to search the images for the faint points of
light moving across the sky in the manner expected for Jupiter
moons. "Searching by eye through the 50 gigabytes of images each
night would be an impossible task," says UBC postdoctoral fellow
Lynne Allen, "so we must use powerful computers to sift through the
data." 

 - Continued -

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