Old Caltech Telescope Yields New Titan Science

Caltech News Release
For Immediate Release
September 22, 2003

Old Caltech Telescope Yields New Science

Contact: Mark Wheeler
(626) 395-8733


PASADENA, Calif. - Meet Sarah Horst, throwback. The planetary science
major, a senior at the California Institute of Technology, spent six
months engaged in a bit of old-time telescope observing. The work led
to some breakthrough research about Saturn's moon Titan, and
indirectly led to funding for a new telescope at Caltech's Palomar
Observatory.

Horst, 21, was looking for a part-time job in the summer of her
sophomore year, and was hired by Mike Brown, an associate professor
of planetary astronomy. Brown and graduate student Antonin Bouchez
knew there had been previous evidence of "weather" on Titan in the
form of clouds. But that evidence was elusive. "Someone would look
one year and think they saw a cloud, then look the next year and not
see a cloud," explains Brown. "What we were after was a way to look
at Titan, night after night after night."

The problem, of course, is that all of the large telescopes like Keck
are incredibly busy, booked by astronomers from around the world who
use the precious time for their own line of research. So Brown and
Bouchez knew that obtaining large amounts of time for a single
project like this was not going to happen.

The solution: Use an old teaching telescope--the hoary 14-inch
Celestron telescope located on top of Caltech's Robinson Lab--to do
cutting edge science that couldn't be done at the largest telescopes
in the world, in Hawaii.

Though the power of the Robinson telescope is weak, and light
pollution from Pasadena strong, which prevents imaging the actual
clouds, the light reflecting from clouds could be imaged (the more
clouds, the more light that's reflected). All that was needed was
someone who could come night after night and take multiple images.

Enter Horst, the self-described "lowly undergraduate." For months,
Horst spent her evenings in Robinson. "I did the setup, which
involved a wheel that contained four light filters," she explains.
Each filter would capture a different wavelength of light. Software
switched the filters; all she had to do, says Horst, was to orientate
and focus the telescope.

Now, modern-day astronomers have it relatively easy when using their
telescope time. Sure they're up all night, but they sit on a
comfortable chair in a warm room, hot coffee close at hand, and do
their observing through a computer monitor that's connected to a
telescope.

Not Horst. She did it the old way, in discomfort. "A lot of times in
December or January I'd go in late at night, and it would be
freezing," says Horst, who runs the 800-meter for the Caltech track
team. "I'd wrap myself up in blankets." Horst spent hours in the
dark, since the old dome itself had to be dark. "I couldn't even
study," she says, "although sometimes I tried to read by the light of
the moon."

A software program written by Bouchez plotted the light intensity
from each image on a graph. When a particular image looked promising,
Bouchez contacted Brown. As a frequent user of the Keck Observatory,
which is powerful enough to take an image of the actual clouds, Brown
was able to call colleagues who were using the Keck that night and
quickly convince them that something exciting was going on. "It only
took about ten minutes to get a quick image of Titan," says Brown.
"The funny part was having to explain to them that we knew there were
clouds because we had seen the evidence in our 14-inch telescope in
the middle of the L.A. basin."

The result was "Direct Detection of Variable Tropospheric Clouds Near
Titan's South Pole," which appeared in the December 19 journal
Nature. It included this acknowledgement: "We thank . . . S. Horst
for many nights of monitoring Titan in the cold."

The paper has helped Brown obtain the funding to build a new 24-inch
custom-built telescope. It will be placed in its own building atop
Palomar Mountain, on the grounds of Caltech's existing observatory.
It's also roboticized; Brown will control the scope from Pasadena via
a computer program he has written.

He'll use it for further observation of Titan and for other imaging,
as well, such as fast-moving comets. "Most astronomy is big," notes
Brown; "big scopes looking at big, unchanging things, like galaxies.
I like to look at changing things, which led to this telescope."

What really made this project unique, though, according to Brown, is
the Robinson scope. "Sarah was able to do something with this little
telescope in Pasadena that no one in the world, on any of their
larger professional telescopes on high, dark mountaintops, had been
able to do," he says. "Sometimes a good idea and stubbornness are
better than the largest telescope in town."

For Horst, while the work wasn't intellectually challenging--"a
trained monkey could have done it," she says with a laugh--it was,
nonetheless, "a cool project. Everything here is so theoretical and
tedious, and so classroom orientated. So in that way it was a nice
experience and reminded me what real science was about."