A periodic comet in an unusual near-circular orbit outside that of Jupiter. It was discovered in 1927 November by the German astronomers (Friedrich Carl) Arnold Schwassmann (1870–1964) and Arthur Arno Wachmann (1902–90). Normally faint at around 16th–17th magnitude, the comet is prone to occasional outbursts in brightness of 5 magnitudes (a factor of 100) or more over a few days. A suggested cause is the crystallization of amorphous ice. Its orbit has evolved somewhat since it was first discovered, and currently has a period of 14.7 years, perihelion 5.76 au, aphelion 6.26 au, eccentricity 0.04, and inclination 9°.4. Its nucleus is estimated to be around 30 km in diameter.

http://cometography.com/pcomets/029p.html Information page at Cometography website.