(Spacewatch) is a distant long-period comet that completes an orbit once every 238 years around the Sun. With a nucleus diameter of , 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 in average.
Orbit Orbital calculations of the comet showed that it has a very eccentric orbit whose perihelion is around from the Sun and an aphelion of , 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 belongs to the “group of long-period comets that are nearly Halley-type” despite its Tisserand parameter being around 2.64.
References
External links
at Seiichi Yoshida's website