Ikeya–Zhang on April 1, 2002
|Discovered by||Kaoru Ikeya, Zhang Daqing|
|Discovery date||February 1, 2002|
|C/2002 C1, C/1661 C1|
|Orbital characteristics A|
|Epoch||October 13, 2002|
|Semi-major axis||51.2136 AU|
|Orbital period||366.5101 yr|
|Max. orbital speed||59 km/s (2002)|
|Min. orbital speed||0.29 km/s[a]|
|Last perihelion||March 18, 2002|
January 29, 1661
|Next perihelion||September 1, 2362|
On February 1, 2002, Chinese astronomer Zhang Daqing from Kaifeng discovered a new comet in the constellation Cetus, and reported it to the IAU. He found that Japanese astronomer Kaoru Ikeya had discovered it earlier than he had, as the time of sunset is earlier than China. According to tradition, since they discovered the new comet independently, the comet was named after both of them. The comet was initially designated as C/2002 C1 (Ikeya-Zhang).
The comet was probably observed in 1661, 341 years earlier, by Polish astronomer Johannes Hevelius. A bright comet had also been recorded by Chinese astronomers in 1661.
The permanent designation "153P" was given to the comet. It has the longest known orbital period of any periodic comet (366.51 years). Its orbital speed around the Sun varies from 59 km/s at perihelion to 0.29 km/s at aphelion.[a]
The comet passed perihelion on March 18, 2002, and with apparent magnitude 3.5, it became the brightest comet since 1997.
- v = 42.1219 √, where r is the distance from the Sun, and a is the major semi-axis.
- "JPL Small-Body Database Browser: 153P/Ikeya-Zhang". Jet Propulsion Laboratory. Retrieved 2011-04-20.
2002-10-02 last obs (arc 341.6 yr)
- "153P/Ikeya-Zhang Orbit". Minor Planet Center.
- Syuichi Nakano (2002-08-13). "153P/Ikeya-Zhang". OAA Computing and Minor Planet Sections. Retrieved 2009-10-04.
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