Sky and Telescope - December 2016 - 84

Focal Point

John Church & William Murray

Three Centuries, One Scope
May 9th dawned clear in central New
Jersey. The venerable 6¼-inch HastingsByrne refractor of the Amateur Astronomers Association of Princeton stood
ready for its third transit of Mercury.
At age 137, the original objective, cell,
and tube (S&T: Mar. 1979, p. 294) were in
good condition. The nearly 8-foot-long,
f/14.6 scope, transferred to a fully computerized Paramount ME mount in 2015,
now oﬀered its eye end at a more convenient height. And recently we'd added a
full-aperture solar ﬁlter to the telescope.
The refractor witnessed its ﬁrst Mercury transit from Honolulu on November
7, 1881, when it was about two years old.
Amateur astronomer Charles Rockwell,
its original owner, had brought it there
from his observatory in Tarrytown, New
York, knowing that the Hawai'ian Islands
were the northernmost land from which
the complete transit would be observable.
Rockwell timed all four contacts and
reported them in The Sidereal Messenger
(the S&T of its day) for April/May 1882.
A year later he took the scope to remote
Caroline Island in the mid-Paciﬁc for the
May 1883 total solar eclipse expedition
(S&T: Mar. 1978, p. 211).
On November 10, 1973, several of our
club members used the telescope, now
in New Jersey, to observe the third and
fourth contacts of that year's Mercury
transit. Despite poor seeing, with the Sun
only about 15°° above the horizon, our timings were closer to the location-corrected
predicted times than the averages of the
total reported observations for those two
contacts (S&T: Jan. 1974, p. 4).
Thus we had high hopes for the 2016
transit of our solar system's smallest
classical planet. A group of us observed
second contact and watched tiny Mercury
84

December 2016 sky & telescope

REX PARKER

A single refractor witnesses the 1881, 1973, and 2016 transits of Mercury.

The Princeton group, with Church at eyepiece and Murray in striped shirt below the historic scope.

march slowly across the Sun's face until
early afternoon. But then clouds, those
implacable foes of astronomers, drifted in
from the west, and we were foiled in our
attempts to see third and fourth contacts.
We still counted the day a major
success. Many club members came out,
several using their own equipment, and
we had about 25 visitors as well.
The Hastings-Byrne refractor has
also observed two consecutive transits of
Venus, separated by 122 years. In 1882,
Rockwell timed the ﬁrst on December
6th from his Tarrytown observatory, as
he related in The Sidereal Messenger for
January 1883. For the transit of June 8,
2004, six of us observed and timed the
third and fourth contacts using eyepiece
projection onto a screen.

We hope to extend our noble telescope's
string of Mercury-transit observations on
November 11, 2019. But it won't be until
December 8, 2125, that another transit of
Venus will be visible locally. Hopefully the
refractor will make it through another 109
years for future amateur astronomers to
enjoy this spectacular sight. ✦
John Church, a retired research scientist,
has been a member of the Amateur Astronomers Association of Princeton since 1971.
Bill Murray works at the New Jersey State
Planetarium in Trenton and has been an
amateur astronomer for more than 40 years.
The authors would like to dedicate this
article to observatory co-chair Gene Ramsey
(in white shirt at right in photo above), who
passed away on September 9th.

Sky and Telescope - December 2016

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