How Comet Hyakutake B2 Was Discovered

Gekkan Tenmon (Monthly Astronomy)
Yuji Hyakutake
April 1996
(Translated to English by Masaki Okamoto)

I searched for a comet for only 4 hours in two nights in January , because we had a long spell of disagreeable weather here since my discovery of 1995Y1 a month ago.

On January 30, as it was likely to clear up at dawn, I left home for my observation place. I wanted to reach there at 3:30 AM ,when the Moon would set in the west. The sky was in a nice condition when I left home, but I found low clouds flowing from the west at the observation place.

The zenith of the sky began to clear around 4:00 AM. I tried to turn my bino culars to see Comet 1995Y1. When the binoculars were pointing almost straight up, I ma naged to catch three objects together, M101, NGC5474 and then 1995Y1 a lit tle smaller than M101. My comet was about 9th magnitude, 8' in diameter. As I made a sketch sitting in a awkward posture, I got a pain in the neck. After sketching I began comet searching freely as usual.

It was about 20 minutes later when I unexpectedly came across an object like a comet. At first I didn't know where it was because of the clouds. Judging from the constellations sometimes glimpsed between floating clouds, the object seemed to be in the southeast of Crow Constellation. I had moved my binoculars to the southern part of the sky without being aware of it.

I was surprised when I mentally connected the stars. Unbelievable! I had thought I already knew the pattern of these stars well!

I was very familiar with the star map of this area because I had often confi rmed 1995Y1 there! I had completely memorized the arrangement of stars around there. The memory was still fresh to me. Too new to forget!

I said to myself, 'I must be dreaming.'

I left my binoculars for a while to calm myself down , and then I started drawing the comet-like object. It was much more condensed than 1995Y1. It was still dark but easy to see. 11th magnitude, 2.5' in diameter.

It was at 4:50 AM when I looked at my watch after marking its position. What I had to confirm first was whether it was moving or not. At 5:40 AM the morning twilight began. I again went back to the binoculars. I couldn't confirm the motion of the object by comparing it with the stars around it. At last I gave up trying to confirm. I concluded to myself that the 'possible comet' should be coming directly toward the Earth. I quit searching when I heard the siren for 6:00 AM at the foot of the hill.

I came back home and checked comets which had already been discovered but I couldn't find reports referring to the comet-like object in question. So I began to draw up a report. I copied the position of this morning's comet-like object on page 332 on Uranometria 2000 from the previous sketch. I had already marked the position of 1995Y1 on the star atlas.

I was stunned by the curious coincidence. The new object was in a very similiar location to where 1995Y1 was found. A few minutes different in R.A and 3 degrees to the east in Dec.

I sent the report to the New Astronomical Findings Infomation Department at the National Observatory. I also sent a fax to Syuichi Nakano (the Calculation Center of O.A.A) and moreover left a message in his answering machine.

At midnight the condition of the sky was poorer than the previous night, and what was worse, a drizzle began to fall at 0:00 AM. Just as I had decided to give up trying to confirm the object that morning, a fax came to me saying that my find was confirmed.

The fax was sent from Ikari in Otu to Nakano at 2:58 AM. And it was sent to me from Nakano again at 3:03AM. I was so glad to be given such a quick response because all I could do at the time was wait. I felt relaxed when I read the fax.

This is the second comet for me, but I can't feel pride in it. I feel terriblly relieved that it was not a mistake. I may feel the same way even if I find more comets.