C/2011 KP36 (Spacewatch)
Long-period comet
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C/2011 KP36 (Spacewatch) is a distant long-period comet that completes an orbit once every 238 years around the Sun. With a nucleus diameter of 55.1 km (34.2 mi),[3] it is one of the largest comets ever discovered.[2]
| Discovery[1] | |
|---|---|
| Discovered by | Spacewatch Terrence H. Bressi |
| Discovery site | Kitt Peak Observatory |
| Discovery date | 21 May 2011 |
| Designations | |
| CK11K36P | |
| Orbital characteristics[2] | |
| Epoch | 22 June 2016 (JD 2457561.5) |
| Observation arc | 8.83 years |
| Number of observations | 3,711 |
| Aphelion | 71.939 AU |
| Perihelion | 4.883 AU |
| Semi-major axis | 38.411 AU |
| Eccentricity | 0.87287 |
| Orbital period | 238.07 years |
| Inclination | 18.987° |
| 173.40° | |
| Argument of periapsis | 180.59° |
| Mean anomaly | 0.108° |
| Last perihelion | 26 May 2016 |
| Next perihelion | 5 June 2254 |
| TJupiter | 2.643 |
| Earth MOID | 3.879 AU |
| Jupiter MOID | 0.079 AU |
| Physical characteristics[2] | |
Mean diameter | 55.1 km (34.2 mi)[3] |
| 0.101 | |
| (B–R) = 1.9±0.3[4] | |
| Comet total magnitude (M1) | 7.5 |
| Comet nuclear magnitude (M2) | 9.5 |
Observational history
It was initially thought to be an asteroid-like object with a very eccentric orbit at the time of its discovery on 21 May 2011.[1] A series of stacked images obtained from observations taken between April and May 2012 showed signs of diffuse cometary activity,[5] with a coma about 6 arcseconds in diameter and a faint tail about 9 arcseconds in length.[6][7]
Orbit
Orbital calculations of the comet showed that it has a very eccentric orbit whose perihelion is around 4.88 AU (730 million km) from the Sun and an aphelion of 71.94 AU (10.762 billion km), almost twice that of Neptune.[4]
NASA / JPL considers this comet as part of the Jupiter-family of comets,[2] however this is highly unlikely as it takes roughly 238 years to complete one full orbit around the Sun. Some astronomers even consider this comet a scattered disc object,[8][9] however Dr. Yan R. Fernandez concluded that 2011 KP36 belongs to the “group of long-period comets that are nearly Halley-type” despite its Tisserand parameter being around 2.64.[4][10]