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Memorable Comets

Comet Seki
C/1961 T1 (Seki)

    This comet played a pivotal role in my life. I had been using a 15cm reflector, but eventually abandoned it. When I switched to a smaller 9cm refractor, I was overwhelmed by queries from other comet hunters: "Why have you chosen a smaller telescope?" Following my example, many of them switched to the same aperture telescopes using the same magnification as my new comet seeker.

    There was a good reason for my switching to the 9cm refractor. I had been struggling in the previous 10 years with the narrow field of view of the 15cm reflector compounded by hopelessly inaccurate focusing. I was physically and psychologically exhausted. To make a fresh start, I started to look for a comet seeker, small but with better focusing and more efficient wider field of view.

    This new comet seeker was equipped with one of the few superb mirrors ground and hand-figured by the renowned mirror maker Mr. Takao Namura. I used to observe at a factory site in front of my house, but I set up a new observing site at the courtyard of my home, about 80 meters south. With the use of a 33mm Erfle eyepiece I obtained a true field width of 3.5 degrees. As a result, my observation became so efficient that I was able to sweep most of the eastern sky within an hour. Later I discovered Comet Ikeya-Seki with this telescope. Prior to the discovery I unsuccessfully searched the northeastern sky. Only 10 minutes remaining, I swept across the southeastern sky and discovered this comet. If I had been using the less efficient 15cm reflector, I definitely would not have discovered this comet. A sharply focused field of view helps the observer's concentration. Fuzzy objects drifting near the edge of the eyepiece field can be clearly differentiated from the stars. Thus I was able to capture this 7th- to 8th-magnitude comet in the low altitude sky (10 degrees above the horizon) already paled by morning twilight. It was a fresh start in my life which until then had been overwhelmed by successive failures.

    Comet Seki was the first comet discovered in Japan in 6 years since the discovery of Comet Honda in 1955. This diminutive 9cm (88mm to be exact) lens started Japan's comet hunting boom.

    Comet Seki hurtled toward the earth as if plunging into it. About a month later, mid November, 1961, it got as close as 0.1 AU to the earth. It moved as much as 35 degrees a day in the sky. On the morning of November 14 the comet shined at 3rd magnitude and its coma was as large as 40 minutes in diameter. Although I did not have much experience with astrophotography, I attached a 200mm telephoto lens to my Pentax and shot the comet, believe it or not, on an altazimuth mounting! It was an early morning event and not reported in newspapers. Very few people in Japan must have seen this event and probably I would have been the only person in Kochi City watching this mid-night spectacle. Seeing Comet Seki moving southward through Centaurus, I relished the success I achieved as a result of my continuous efforts.

Comet Seki (C/1961 T1) moving southward in Centaurus
At 4 am November 14 , 1961, J.S.T.
5-minute exposure with 200mm f/3.5 telephoto lens

Copyright © 2006 Tsutomu Seki.