Sky & Telescope - September 2016 - 25

To solve this problem, McAlister asked his Georgia
State University colleague Laszlo Sturmann to develop
an optical system that would let the public observe from
a more accessible location. Sturmann ﬁnished the design
in early 2012, and by September of that year his relay
system had seen ﬁrst light. Meanwhile, Dave Jurasevich,
then Mount Wilson Superintendent, coordinated eﬀorts
to improve the telescope's pointing and tracking. The ﬁrst
public observing sessions commenced in 2013, and the
program in its current form started in the spring of 2015.
In Sturmann's relay system, the light from the 100inch telescope reﬂects oﬀ a 6-inch ﬂat mirror before
the Cassegrain focus. The light next goes "backward"
through a Meade 152ED f/9 apochromatic refractor,
which acts like a 1,368-mm eyepiece and recollimates the
beam. The light is then brought to new focus by a 5-inch
Explore Scientiﬁc refractor. As Sturmann says, "This is
a very simple system, and the beauty of it is that both the
Meade objective and the Explore Scientiﬁc refractor are
used as they were intended, therefore the relay system
itself has excellent image quality. It doesn't degrade the
100-inch telescope."
The relay system changed the original Cassegrain's
focal ratio from f/16 to f/11.25 and made it possible
to observe from a short ladder. The Explore Scientiﬁc
refractor accommodates standard 2-inch eyepieces.

Ever since my 2002 observing session on the 60-inch,
I've wondered what some of my favorite objects would
look like if I could view them through this grand old
reﬂector. So it was with particular good fortune that my
longtime friend Bob Young informed me that he and a
small group of ASH members were planning an observing night on the 100-inch. Bob is a retired planetarium
educator with the State Museum of Pennsylvania in Harrisburg, and he served as president of the Astronomical
League from 1978 to 1980.
Using the Mount Wilson Observatory's website
(mtwilson.edu/100in.html), Bob reserved a half night on
November 2, 2015, for a fee of $2,700 (a full night goes
for $5,000). Bob kept the invitation list small so each person could enjoy ample time at the eyepiece. Besides Bob
and me, the other ASH members who ﬂew to Southern
California (and split the cost) were Jim Davis, Tony Donnangelo, Bob Hoover, and Roxanne Kamin.
Though we'd planned to observe that Monday night,
Shelley Bonus, our contact at the Mount Wilson Institute, called on both Monday and Tuesday mornings with
bad news: a weather front in the area meant it was very
likely we'd be clouded out and so we shouldn't bother to
drive up the mountain. Fortunately, there's plenty to do
in the L.A. metro area, so we spent the daylight hours on
Monday and Tuesday touring Griﬃth Observatory, the
California Science Center, and Warner Brothers Studios.

CINDY HUNT / MOUNT WILSON INSTITUTE

The Road to Mount Wilson

BEHEMOTH Be prepared to be awed by the size of the 100-inch when
you visit it in its dome on Mount Wilson. When aimed near the zenith, the
87-ton telescope towers some 40 feet above observers' heads.

Sk yandTelescope.com September 2016

http://www.mtwilson.edu/100in.html http://www.SkyandTelescope.com

Sky & Telescope - September 2016

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