The comet was discovered by the Japanese amateur astronomer
Kaoru Ikeya on 2 January 1963. At that time Kaoru Ikeya was 19 years old and used a self-made 8-inch telescope. The comet was then located three degrees southwest of
π Hydrae, had an estimated magnitude of 12 and was diffuse. He confirmed his finding the next day and telegraphed his discovery to the
Tokyo Astronomical Observatory, and the new comet was photographed with the Brashear Astrograph. The comet at discovery was moving rapidly southwards and after 25 January could not be observed from the northern hemisphere. The comet became circumpolar in the southern sky and between February 11 and February 13 was in the constellation of
Octans, near the south celestial pole, and then moved northwards. The comet was brightening during February and 15 February was the day of the
closest approach of the comet to Earth, at a distance of . The comet grew a tail that photographically was estimated to be 8 degrees long on 18 February, while it reached third magnitude and was visible with
naked eye. The tail originally had a simple straight form but its structure became more complex by the end of the month. By March 1963 the comet again became visible in the northern hemisphere. By 10 March, the apparent magnitude of the comet was estimated to be 4.5. The length of the tail was reported to be as long as nearly 20 degrees on 21 March, the date of the perihelion. After perihelion the comet was in
conjunction with the Sun and could not be observed. It reached its minimum
elongation of 4° on 12 April. The comet was recovered in mid-May in the morning sky and was brighter than expected, as the comet faded at a slower rate than it brightened, having a magnitude of 7 to 8. The brighter than expected comet led to some reports that this was a new comet, but photographic observations revealed that there was only one comet in the region, comet Ikeya. In long exposure photographs in mid-June the tail was more than half a degree long. The comet faded rapidly in September and October and was last observed on 12 October. == Scientific results ==