C/1964 N1 (Ikeya)
Long-period comet discovered by Kaoru Ikeya in July 1964.
C/1964 N1 (Ikeya), also called Comet 1964f, is a long-period comet. Japanese amateur astronomer Kaoru Ikeya spotted it on 3 July 1964. It was his second comet discovery, following C/1963 A1. At the time, the comet was in the morning sky, within the constellation Taurus near the Hyades star cluster, with an estimated apparent magnitude of 8. It was moving southeast.
The comet brightened through July. On 19 July, Jim Young at Table Mountain Observatory saw it without a telescope. It reached perihelion on 1 August 1964, when its apparent magnitude hit 2.7. By 6 August, it remained visible to the naked eye as it passed within 1–2° of the star Rigel. After that, observation became difficult because the comet was low in the morning twilight. Its closest approach to Earth came on 12 August, at about 0.2 AU (30 million km), with a solar elongation of 31°. On 15 August, S. Archer in Australia reported a magnitude of 2.8 and a tail stretching 4.5 degrees. The comet became visible from the northern hemisphere in the evening sky in late August, but it sat low near the horizon and had faded noticeably.
By 2 September, its magnitude was estimated at 6.5, and by 12 September it had dimmed to 8.5. The final detection came on 7 October 1964, when the comet had a magnitude of 10.4.
Spectra obtained on 29 and 30 July at Mount Wilson Observatory, along with photoelectric measurements, allowed scientists to gauge relative abundances. The spectrum showed C2, C3, CH, and CN. In the coma near the nucleus, the ratios N(CH)/N(CN) and N(C3)/N(CN) were both about 0.3.
The comet is considered the parent body of several meteor showers. Modeling indicates it created four streams that intersect Earth’s orbit. The first shower linked to C/1964 N1 (Ikeya) is the July ξ Arietids. It is also thought to be the parent of the ϵ-Geminids, and possibly the ξ-Geminids. All these showers are diffuse and produce few meteors.
Quick Facts
- Discoverer
- Kaoru Ikeya
- Discovery Date
- 3 July 1964
- Designations
- 1964f
- Epoch
- 1964-Jul-28.0
- Observation Arc
- 56 days
- Obs
- 36
- Aphelion
- 110.97 AU
- Perihelion
- 0.822 AU
- Semimajor
- 55.90 AU
- Eccentricity
- 0.9853
- Period
- 418 years
- Inclination
- 171.92°
Facts from the source article.
Lore & Background
The comet was discovered by Japanese amateur astronomer Kaoru Ikeya on 3 July 1964, his second comet discovery after C/1963 A1. At discovery, it was in the morning sky in the constellation Taurus, near the Hyades star cluster, with an estimated magnitude of 8 and moving southeast. It brightened through July and was first observed with the naked eye on 19 July by Jim Young at Table Mountain Observatory. The comet reached perihelion on 1 August 1964, and by 6 August it was visible to the naked eye as it passed 1–2° from Rigel. After that, it became difficult to observe in morning twilight. Its closest approach to Earth was on 12 August at about 0.2 AU and a solar elongation of 31°. On 15 August, S. Archer in Australia reported a magnitude of 2.8 and a tail 4.5 degrees long. The comet became visible from the northern hemisphere in the evening sky in late August, low near the horizon and faded noticeably. By 2 September its magnitude was estimated at 6.5, by 12 September at 8.5, and it was last detected on 7 October 1964 at magnitude 10.4.
Reader's Guide
The comet's scientific significance stems from spectral observations on 29 and 30 July 1964 by Mount Wilson Observatory, which revealed the presence of C2, C3, CH, and CN. Photoelectric measurements allowed relative abundances to be determined: the N(CH)/N(CN) and N(C3)/N(CN) ratios were both about 0.3 in the coma near the nucleus. These measurements contribute to understanding the chemical composition of long-period comets. Additionally, C/1964 N1 (Ikeya) is considered the parent body of several meteor showers. Modeling has shown it creates four streams intersecting Earth's orbit. The first associated shower is the July ξ Arietids. The comet is also considered the parent of the ϵ-Geminids and possibly the ξ-Geminids. All these showers are diffuse and have few meteors, indicating the comet's debris is sparsely distributed. The comet's legacy includes its role in linking a specific long-period comet to multiple meteor showers, a relatively rare attribution.
Did You Know?
- C/1964 N1 (Ikeya) was the second comet discovered by Kaoru Ikeya, after C/1963 A1.
- The comet's spectrum showed the presence of C2, C3, CH, and CN.
- It is considered the parent body of the July ξ Arietids meteor shower.
- The comet's closest approach to Earth was on 12 August 1964 at about 0.2 AU.
More in Named Comets, Part 3 1-24
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