The Story of a Comet Hunter's Life

    In the previous episode, I wrote over a number of pages about the Martian Army by Juza Unno. I did so because the book was one of my fortunate encounters that had helped me develop interest in science in my youth. I think that, if "Comet Moro" created by Unno hadn't appeared, Comet Seki of 1961 might have not come about. This shows that such encounters in one's childhood are very important and they can determine the course of one's entire life. I sometimes think that discovering new astronomical objects or publishing books on related subjects may inspire and help the development of young people.

    Around the time when the Martian Army was being serialized in Sho-kokumin Shinbun (the Young Citizens Newspaper), I was in the 3rd or 4th year of elementary school. Although World War II was not far from people's mind, life at school was peaceful and relaxing. Children were gathering here and there and busily talking about the future development in the Martian Army. In the schoolyard the sound of kendama or cup-and-ball was echoing and in the sky airplanes were flying.

    Our homeroom teacher was Mr. Kei Okamoto. He was a young teacher of small physical stature wearing glasses. He excelled in physical education, Japanese calligraphy, and painting and has personal traits that made him the admiration of children. In particular, he was very knowledgeable about insects and plants. In his science class, he often told us about his experiences going deep into the Shikoku Mountains to explore nature and tried hard to find new species even taking risks at times. By nature I wasn't good at schoolwork, but in Mr. Okamoto's science class I found myself completely lost in his stories. To be honest, I forget anything written in the textbooks, but surprisingly I remember his stories very clearly. These stories, which might appear to be a digression from teaching, often turn out to be valuable in life after leaving school. It is important for the teachers to follow the textbooks closely at elementary school, but it will be much more valuable for children that the teachers teach the subjects they really love and tell their experiences with passion.

    My childhood before meeting Mr. Okamoto was miserable. My first two years at school were wasted due to illness. I shudder at the thought that, if I hadn't met Mr. Okamoto in my third year, I would have been a hopeless failure. His stories were refreshing. Everything he told us was surprising and drew us into the mysterious world of nature teaching us the joy and excitement of learning science through experience. Until then, I had been often reprimanded by teachers and frequently absent from school, but in my third year, I suddenly found myself enjoying school. My parents were very thankful to Mr. Okamoto. My mother often visited him at home and thanked for his influence on me. Forty years later, he visited us without notice. He announced his visit at the unlit doorway saying "Excuse me" with a slightly rising intonation. My mother said she immediately knew that it was Mr. Okamoto. Teachers at elementary school are an unforgettable presence both for children and their parents.

    Around this time, a great naked-eye comet appeared. It was Comet Cunningham. Until relatively recent years, I had thought that Comet Cunningham was the comet which appeared in “the Martian Army”. It is probably because the Sho-kokumin Shinbun often reported on the naked-eye comet Cunningham around the time when the Martian Army was being serialized in the same paper.

    Comet Cunningham was discovered on September 5, 1940 by Leland E. Cunningham at Oak Ridge Observatory in the U.S. Cunningham was a graduate student at Harvard College Observatory at that time. The comet seems to have displayed a magnificent sight in the evening sky later becoming visible to the naked-eye. I have no clear recollection of seeing this comet, but the appearance of a mirage-like fuzzy comet hanging in the darkening western evening sky over the city comes and goes in my mind like a dream or illusion. Cunningham was very productive in recovering of periodic comets and orbital calculations of newly discovered comets. It was Cunningham that made initial calculations of the orbit and gained an orbital period of 880 years for Comet Seki (1961f), my first comet discovery made in October 1961, 21 years after my encounter with Comet Cunningham. The name of the renowned Brian Marsden was not seen yet in the frontline of the then cometary field.

    Because Comet Seki (1961f) is the first comet I discovered, I attempted to calculate its orbit using very limited observation data and reported the prediction of its positions. I obtained an orbital period of about 900 years, but Cunningham’s calculations were closer to the actual positions. Under Dr. Ichiro Hasegawa’s guidance, I made calculations to establish the comet’s definitive orbit, but it turned out to be not precise enough. In those days, it involved a huge amount of work using a seven-digit log table and trigonometric function table in order to work out O-C values for each of many observations. Besides, it would probably have taken several years if you had tried to determine the orbit taking account of perturbation by the 9 planets. In the meantime, the use of electronic calculators accelerated making calculations by hand obsolete.

    People in those days did a tremendous job in orbital calculations whether it was logarithmic calculations or antilogarithm calculations by a manual calculator. For orbital calculations of periodic comets of 5-6 years, they simplified calculations incorporating the perturbation by Jupiter and Saturn only. In spite of this, they contributed to the rediscovery of comets by approximation. One memorable comet is Comet Perrine famous for its occasional explosive outbursts and ninja-like disappearance. At the time of its 1995 return, Dr. Hasegawa made simplified calculations of perturbation based on the existing orbit and announced the prediction publicly ahead of others. I was involved in part in the prediction of its positions. Comet Mrkos discovered unexpectedly in October 1955 was the long-lost Comet Perrine. It was about 6 magnitude brighter than predicted. It was Dr. Hasegawa that identified this Comet Mrkos with Comet Perrine, one of his great achievements in his study of cometary orbits.

    The then Skalnate Pleso Observatory began producing great results in comet search around 1947 with the observatory’s director Antonin Bekvar himself operating a comet-seeker with several staff members joining him. They worked hard for about 10 years and Antonin Mrkos alone discovered 10 comets including the recovery of a periodic comet . It is said that it took him over 300 hours on the average to discover one new comet. It would be the first and last time that a professional observatory devoted its time and effort to visual search for comets. It is well-known that the LINEAR in the U.S. has been very productive in comet discoveries equipped with up-to-date facilities such as a combination of one-meter-class Schmidt camera and CCDs. However, their main purpose of search is minor planets.

    The Skalnate Pleso Observatory is said to have used several pairs of new wide-angle binocular telescopes, but in those days the details were hidden behind the Iron Curtain. As a comet hunter, I was especially interested in high-quality comet seekers and wrote in English to Ms L’udmila Pajdusakova at Skalnate Pleso for information on these binocular telescopes, but did not receive any reply. However, later (around 1959) I learned that the emerging UK comet hunter George Alcock had been using binoculars of similar aperture. Dr. Ichiro Hasegawa had an opportunity to look through the comet seeker used by Mrkos when visiting Skalnate Pleso Observatory at the time when the IAU conference was being held in Czech Republic in the summer of 1998. This pair of Somet-made binoculars was designed for astronomical use with an aperture of 10cm at 25 power. They must have obtained a real field of view of probably 4 degrees. The capability of their comet seekers is undoubtedly superb, but a larger contributing factor to their achievements may be their magnificent starry skies over their observatory at an elevation of 1600 meters above sea level. Incidentally, the night Dr. Hasegawa visited the observatory was cloudy and he could not see any stars.

    Let’s return to the topic of Comet Perrine. Around the time when Mrkos discovered this comet in October 1955, I was searching in and around Cancer where the comet was discovered, following the prediction by Dr. Hasegawa. It was October 18, the day before the comet was discovered. The equipment I was using was a reflecting comet seeker of a 15cm aperture at 24 power. In those days, the night sky over the city of a population of 200,000 was really dark and the stars were bright and clear. Sadly, my comet seeker passed through the area without any hesitation where Comet Perrine (at 9th magnitude) was lurking. Mr. Shigeru Kanda concluded that the comet must have made an outburst immediately after my search. My recollection is the predicted magnitude of this comet was 14-15.

    Comets like this with a tendency of sudden outbursts made orbital calculations complicated due to non-gravitational effect (a kind of rocket-propulsion effect). Comet Schaumasse was recovered at 20th magnitude by Geisei on September 25, 1992, but James Scotti at Kitt Peak National Observatory with a powerful CCD camera missed the target. It was because of unpredictable motions of this comet due to non-gravitational effects. Our recovery of this comet owes much to Mr. Kenji Muraoka, who had been specializing in the study of this type of comets. Although the difference with or without considering non-gravitational effects was subtle, it would become significant over a long period of time. Some of the comets discovered more than 100 years ago are currently lost. This happens because the orbits are not well determined and also affected by non-gravitational effects. A number of the short period comets discovered by Barnard of U.S. and Denning of U.K. a long time ago are completely lost. Considering that they lose brightness and become fainter at each orbit, it will be a miracle if they are recovered. 　

    Next time I will take you again to the fun-filled school yard of my elementary school days. There was an incident that I must tell in order to continue this story.