C/1967 Y1 (Ikeya–Seki)
Non-periodic comet
From Wikipedia, the free encyclopedia
Comet Ikeya-Seki, formally designated as C/1967 Y1, is a retrograde non-periodic comet discovered by Kaoru Ikeya and Tsutomu Seki on 1967. It is the second comet discovered by the two Japanese astronomers after C/1965 S1.[1]
| Discovery[1] | |
|---|---|
| Discovered by | Kaoru Ikeya Tsutomu Seki |
| Discovery site | Japan |
| Discovery date | 28 December 1967 |
| Designations | |
| 1968 I, 1967n[2] | |
| Orbital characteristics[3] | |
| Epoch | 18 March 1968 (JD 2439933.5) |
| Observation arc | 676 days (1.85 years) |
| Number of observations | 300[4] |
| Aphelion | 4,020 AU |
| Perihelion | 1.697 AU |
| Semi-major axis | 2,011 AU |
| Eccentricity | 0.99916 |
| Orbital period | 90,185 years |
| Inclination | 129.315° |
| 255.321° | |
| Argument of periapsis | 70.864° |
| Last perihelion | 25 February 1968 |
| TJupiter | –1.02 |
| Earth MOID | 1.0675 AU |
| Jupiter MOID | 0.0276 AU |
| Physical characteristics[4][5] | |
| Comet total magnitude (M1) | 4.0 |
| 6.3 (1968 apparition) | |
Discovery and observations
C/1967 Y1 was the 14th comet discovered in 1967 when both Kaoru Ikeya and Tsutomu Seki spotted on the evening of 28 December.[6] At the time, it was a 9th-magnitude object within the constellation Ophiuchus.[a] The comet's position remained circumpolar throughout its last perihelion, thus giving astronomers a rare opportunity to observe it all night long.[6]
It reached its peak brightness of 6.3 on 4 February.[4] By 25 February 1968, the comet faded to an apparent magnitude of 7.1 and developed a very faint tail.[7] Photometric spectroscopy of the comet's tail together with comets C/1968 L1 and C/1968 N1 has shown its forward scattering to be gray in the 3500–6300 Å spectrum, in contrast to the reddening of the dust tail seen in other comets.[8] The comet was last observed from the Kitt Peak Observatory on 4 November 1969.[5]
