Comet Siding Spring 3, also known as (Siding Spring), is a Halley-type comet with a 21.86-year orbit around the Sun. It is one of several comets discovered by the Siding Spring Survey (SSS).
Observational history was first observed as an asteroid-like object on 20 April 2006. Later, cometary activity was observed by the European Southern Observatory by Stephen C. Lowry and Alan Fitzsimmons around July 2006, reclassifying it from asteroid to comet. Precovery observations were obtained up to 6 July 2005, though unconfirmed observations of the comet being seen as early as March 1986 were reported. Javier Licandro and other astronomers from the La Palma Observatory reportedly failed to detect the coma first seen by Lowry around the same time, suggesting that is either an extinct or dormant comet.
It was accidentally recovered by Robert Weryk as a stellar-like object on images taken by Pan-STARRS on 16 June 2026, two years ahead of its next perihelion in 2028.
Physical characteristics Infrared observations from the NEOWISE mission in 2018 revealed a nucleus about in diameter. However, data obtained from the Akari mission suggests a much larger nucleus at in diameter assuming a geometric albedo of 0.035–0.045, and a bare nucleus (i.e. without cometary activity) was observed. This makes it one of the largest cometary nuclei known. The comet appeared reddish in spectroscopic observations, comparable to those of D-type or X-type asteroids.
Notes
References
External links
at the Minor Planet Center database at Seiichi Yoshida's website