Discovered on 1927, Nov. 15 by Arnold Schwassmann and Arno Arthur Wachmann from Hamburg Observatory, Bergedorf, Germany, this comet is well known in the astronomical comunity for its periodic (although not regular) outbursts.
When in “quiescent” state its magnitude is around 17 (see image above), but several times per year it can reach mag 14-15 or even brighter (the brightest outburst was at mag. 10).
A highly changing surface processes (associated with transition from amorphous to crystalline water ice) are the suspected reasons for its behaviour. More information can be found here.
Its orbit around the Sun is almost circular (e=0.04) and its semimajor axis (a=5.99 AU) puts it just outside the orbit of Jupiter, with a current period of 14.7 years; for all its features it is catalogued as an active Centaur, with an estimeted diameter of around 30Km.
Maybe a spacecraft towards it will be not a bad idea! 🙂
The image below shows the last outburst to date (discovered by Francois Kugel from A77 – Dauban on 2011, Jan. 24.18) in progress…

From our measures, its magnitude has changed from 16.9 on Jan. 17 to 15.2 on Jan. 25.