C/2011 KP36 (Spacewatch)

C/2011 KP36 (Spacewatch)
Discovery
Discovered bySpacewatch
Terrence H. Bressi
Discovery siteKitt Peak Observatory
Discovery date21 May 2011
Designations
CK11K36P
Orbital characteristics
Epoch22 June 2016 (JD 2457561.5)
Observation arc8.83 years
Number of
observations		3,711
Aphelion71.939 AU
Perihelion4.883 AU
Semi-major axis38.411 AU
Eccentricity0.87287
Orbital period238.07 years
Inclination18.987°
173.40°
Argument of
periapsis		180.59°
Mean anomaly0.108°
Last perihelion26 May 2016
Next perihelion5 June 2254
TJupiter2.643
Earth MOID3.879 AU
Jupiter MOID0.079 AU
Physical characteristics
Mean diameter
55.1 km (34.2 mi)
0.101
(B–R) = 1.9±0.3
Comet total
magnitude (M1)		7.5
Comet nuclear
magnitude (M2)		9.5

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), it is one of the largest comets ever discovered.

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. A series of stacked images obtained from observations taken between April and May 2012 showed signs of diffuse cometary activity, with a coma about 6 arcseconds in diameter and a faint tail about 9 arcseconds in length.

Observations in July 2015 from the Leoncito Astronomical Complex (CASLEO) in Argentina showed that the comet had a dust mass-loss rate of about 282.86 kg/s (623.6 lb/s) in average.

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.

NASA / JPL considers this comet as part of the Jupiter-family of comets, 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, 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.

References

  1. 1 2 J. V. Scotti; T. H. Bressi; R. S. McMillan; et al. (14 June 2011). "2011 KP36". Minor Planet Electronic Circular. 2011-L56. ISSN 1523-6714.
  2. 1 2 3 4 "C/2011 KP36 (Spacewatch) – JPL Small-Body Database Lookup". ssd.jpl.nasa.gov. Jet Propulsion Laboratory. Retrieved 23 May 2025.
  3. 1 2 J. K. Rigley; M. C. Wyatt (2022). "Comet fragmentation as a source of the zodiacal cloud" (PDF). Monthly Notices of the Royal Astronomical Society. 510 (1): 834–857. doi:10.1093/mnras/stab3482.
  4. 1 2 3 O. Ivanova; V. Rosenbush; I. Luk’yanyk; L. Kolokolova; et al. (2021). "Observations of distant comet C/2011 KP36 (Spacewatch): photometry, spectroscopy, and polarimetry" (PDF). Astronomy & Astrophysics. 651 (29): 1–22. Bibcode:2021A&A...651A..29I. doi:10.1051/0004-6361/202039668.
  5. ↑ L. Buzzi (20 May 2012). "Discovery of cometary appearance of 2011 KP36". G. V. Schiaparelli Astronomical Observatory. Retrieved 23 May 2025.
  6. ↑ T. H. Bressi; R. Holmes; T. Vorobjov; L. Buzzi; S. Foglia; et al. (17 May 2012). D. W. Green (ed.). "Comet C/2011 KP36 (Spacewatch)". Central Bureau Electronic Telegrams (3109). Bibcode:2012CBET.3109....1B.
  7. ↑ L. Buzzi; J. V. Scotti; A. C. Gilmore; et al. (17 May 2011). G. V. Williams (ed.). "C/2011 KP36 (Spacewatch)". Minor Planet Electronic Circular. 2012-K12. Bibcode:2012MPEC....K...12B. ISSN 1523-6714.
  8. ↑ R. S. Garcia; R. Gil-Hutton; E. Garcia-Milani (2020). "Observational results for five short-period and five long-period comets". Planetary & Space Science. 180 104779. Bibcode:2020P&SS..18004779G. doi:10.1016/j.pss.2019.104779. hdl:11336/153861.
  9. ↑ J. M. Bauer; T. Grav; E. Blauvelt; A. K. Mainzer; J. R. Masiero; et al. (2013). "Centaurs and Scattered Disk Objects in the Thermal Infrared: Analysis of WISE/NEOWISE Observations". The Astrophysical Journal. 773 (1): 1–11. arXiv:1306.1862. Bibcode:2013ApJ...773...22B. doi:10.1088/0004-637X/773/1/22.
  10. ↑ O. Ivanova; L. Kolokolova; I. Luk’yanyk; V. Kleshchonok; et al. (21 September – 9 October 2020). Scattering properties of dust in C/2011 KP36 (Spacewatch). 14th Europlanet Science Congress. Bibcode:2020EPSC...14..346I. doi:10.5194/epsc2020-346. EPSC2020-346.
  11. ↑ Y. R. Fernandez. "Long-period comets that are nearly Halley-type". Retrieved 23 May 2025.