Reports from Geisei Observatory <August 20, 2006>
Comet Taylor (69P/Taylor)
Comet Taylor appears regularly these days, but it had been
lost for 61 years after its discovery in 1916. As regards the orbit of
this comet, its perturbation was calculated by Mr. Shigeru Kanda (Japan
Astronomical Study Association) and Mr. Toshikazu Higami (Kyoto University
Kwasan Astronomical Observatory) in Japan. The predicted positions of the
comet were frequently announced at the time of each close approach. In
those days, however, unlike today, calculations were made manually using
calculating machines and logarithms, which was not only inefficient, but
major errors such as the use of incorrect quadrants occurred. In spite
of these problems on the ground, the comet must have orbited the sun many
times maintaining a certain level of brightness. I recall that in the 1950's
I searched with a 15cm comet seeker the area of the sky around Gemini in
autumn following the predictions announced by Mr. Kanda. My observing site
was at my home in Kochi. In those days the sky over Kochi was excellent
and generally 11th-magnitude comets were visible. (Comet Taylor's predicted
magnitude was 9 to 10.)
Things changed after Dr. Marsden began to play a major role.
The predicted positions were announced in BAA's Handbook around 1976, which
turned out to be considerably different from Mr. Kanda's predictions. In
those days it was not possible to calculate perturbation on the daily basis.
I searched for the comet using the 40cm "comet"
telescope just installed at Geisei following BAA's predictions and found
a faint glow not far from the predicted position. This was Comet Taylor
itself which had been seen for the first time in 61 years since its discovery.
While I was waiting for a period of 24 hours in order to confirm its motion,
I received a telegram of the detection of the comet by Palomar's 122cm
Schmidt camera. I thought the comet was 15th magnitude at that time, but
my remeasurement put it at 13th magnitude using GSC comparison stars. It
was indeed big news and Mr. Hiroki Kosai's excited voice at the other end
of the line is still ringing in my ears
In the following year, too, my comet telescope caught a big
"fish" and established its reputation. This was achieved in spite
of the sloppy focusing and motor drive systems of the telescope, the worst
kind in the world.
1977UT RA (2000.0) Decl. m1
Jan.14.62257 06 32 14.46 +21 08 28.9 13.1 372
15-minute exposure from 23:49, January 14, 1977 J.S.T.
40cm f/5 reflector, FLO-II photographic plate