The Story of a Comet Hunter's Life

    It was December 28 in 1970. Just a few days before the end of the year, an urgent phone call came at night from Mr. Nobuhisa Kojima living in Isshikicho, Aichi prefecture. According to him, while searching for Comet Neujmin 2 in the early morning of the day. he spotted a 14th-magnitude object which was suspected to be Neujmin 2. Neujmin 2 was a periodic comet discovered in Russia in 1916, but had been lost for a long time. Orbit calculators around the world had been searching for this comet and published predicted positions of the comet at every expected apparition.
    Once the predictions were published in the BAA Handbook, Mr. Kojima and I decided to jointly search for the comet. Although the orbital period is about 6 years, the prediction of the timing of its perihelion passing must be grossly inaccurate after having been lost for so long. We started our search competitively as early as in the autumn of that year by dividing the area of search: Mr. Kojima was given the eastern side of the predicted positions and the western side was given to me. Was Neujmin 2 really in our search area?
    In those days Mr. Kojima was using a 31cm-aperture f/5 mirror figured by himself, while I was using Mr. Kojima's 21cm f/5 mirror. The film used was very popular Tri-X. We had good results either by sensitizing with Pandol or developing normally with Kodak D-19.
    Comets often show non-gravitational effects after a long period of a "wandering life" in space and tend to shift the date of perihelion passage forward, though we cannot generalize it. Therefore, Mr. Kojima concluded that searching the area of negative ΔT or the eastern side of the perihelion position would be more promising. His prediction turned out to be perfect and he spotted a 14th-magnitude cometary image at the predicted position and expected brightness. Just at a glance, everybody would think it was the return of Neujmin 2.
    When the first report of the discovery reached Tokyo Astronomical Observatory at Mitaka, Tokyo, Mr. Koichiro Tomita in the astronomical object search section told me that there was no doubt that this was Neujmin2. Mr. Tomita himself was actually searching for this comet at Dodaira using a 91cm telescope. Just looking at the approximate orbital period, Mr. Shigeru Kanda of Kanagawa prefecture said at the first Comet Conference, "There is no no need for complicated calculations. This is definitely Neujmin 2." He even reported the discovery of Comet "Neujmin-Kojima" in the Yamamoto Circular. I measured the position of the comet from Mr. Kojima's photographic images. I calculated the initial provisional positions including my observations made at my residence. Mr. Kanda looked at my provisional orbital elements and came to his conclusion of Comet "Neujmin-Kojima".
    However, Dr. Ichiro Hasegawa and Dr. Brian Marsden were a little more cautious. In Yamamoto Circular, they wrote that it would be necessary to see the results of further observations to identify it to be Neujmin 2. The orbits of Neujmin 2 and the newly discovered comet are remarkably similar. Although there was a slight difference in the time of the perihelion passage T and perihelion distance q, all the other elements were very close. This comet passed very close to Jupiter in the past, as a result of which a force beyond conventional perturbation calculations might have worked on the comet. I asked Dr. Marsden this question straightforward. As if he were thinking along the same line, he replied through Dr. Hasegawa that even by varying the mass of Jupiter, it did not come to agree with the calculated orbit of Neujmin 2. After all these developments, the discovery of Comet Kojima was confirmed and remains sound and well. However, Neujmin 2 has been lost in space and not reappeared even once.

    More than 30 years have passed since. Here is an incident I have to tell you now. In 1976, the year of Neujmin 2's apparition, Belyaev of BAA published the precise predictions of the comet including the expected maximum magnitude of 13. By then I had shifted my observing site from Kamimachi (my residence) to Geisei village. I began using a 40cm f/5 reflector, a scope twice as big as the one I previously used. I was able to build it thanks to Mr. Kojima's generosity.
    We caught a comet-like image at the predicted position of Comet Neujmin 2 in mid-March, 1976. The Pleiades was shining nearby. This was reported to Mr. Kojima in Aichi prefecture. The following day, he photographically searched that particular area and captured this mysterious object. However, we didn't have any more chance to observe it again due to poor weather and its low position in the evening sky. Would Neujmin 2 be lost into the darkness forever?
    Seven years had passed since then. Mr. Kojima and I were inside the famous Ryugado cave at Tosayamada in Kochi prefecture. This limestone cave is 1.5 kilometers long and was discovered in the early 1930s. It is a relatively new cave. It was dark inside the cave and people used to explore it holding a torch. So many bats were hanging from the limestone ceilings that the ceilings appeared as if painted black. Deep inside the mysterious cave, eerie cries of strange beasts were echoing. The sound of water falls was always heard from deep under the ground. They say what has been explored so far is a tiny part of the whole cave system.
    Walking carefully watching our insecure footing, our conversation naturally drifted to Comet Neujmin 2.

    "Kojima-san, you are lucky to find a periodic comet for your first discovery, " I started.
    Modest Mr. Kojima replied, "Thank you. Thanks to people who observed to confirm it, I was able to make my first discovery."
    "It's great the name of Comet Kojima returns every 7 years. I wish I could find a periodic comet too."
    "But how did Mr. Tomita and Dr. Kanda decide that the object was Neujmin 2 so soon after the discovery?" said Mr. Kojima with his glasses reflecting faint light inside the cave.
    "It is probably what is called the sixth sense of people who had done orbital calculations and observations for a long time. To be honest, I still cannot completely deny the possibility of the two comets being identical. Since that time, I have searched hard for Neujmin 2 at every apparition, but haven't been able to find it. "
    "Was it very faint initially when it was discovered in 1916?" Mr. Kojima asked.
    "No, it was extraordinarily bright. Neujmin probably found it using a small comet seeker. It was found in February 1916 at 9th to 10th magnitude. The comet had been followed for the next 3 months. The last observation made on May 7 showed it was 10th to 11th magnitude with a 2.5'-daimater coma. The standard brightness of this comet based on that year's observations is 11.0 magnitude. This means it will become visually observable."
    Mr. Kojima said, "As Dr. Whipple said some time ago, it is true that short periodic comets become considerably faint in 100 years, isn't it?"
    "But there is a possibility it becomes very bright suddenly. Isn't it possible that at the time of discovery it happened to be very bright?" I replied.
    "It is wandering in dark space with its whereabouts not known to anybody, but let's hope it brightens and reappears someday." Mr. Kojima said calmly.

    While walking in a dark narrow maze, we saw faint light in the distance which looked like the exit of the cave, as if it were symbolizing Mr. Kojima's hopeful word.