C/2013 US10 (Catalina) is an Oort cloud comet discovered on Oct 31, 2013 by the Catalina Sky Survey using a 0.68-meter (27 in) Schmidt–Cassegrain telescope. By September 2015 the comet was around apparent magnitude 6.

When discovered, observations from a Sep 12, 2013 object were used in the preliminary orbit determination giving an incorrect solution of only 6 years. But by Nov 6, 2013 a longer observation arc (from Aug to Nov) made it apparent that the initial solution had the wrong object.

By early May 2015 the comet was an apparent magnitude 12 and had an elongation of 60 degrees from the Sun as it moved further into the southern hemisphere. The comet came to solar conjunction on Nov 6, 2015, around magnitude 6. The comet came to perihelion (closest approach to the Sun) on Nov 15 at a distance of 0.82 AU from the Sun. At perihelion, it had a velocity of 46.4 km/s (104,000 mph) w.r.t. the Sun which is slightly greater than the Sun's escape velocity at that distance. It crossed the celestial equator on Dec 17 becoming a northern hemisphere object. On Jan 17, 2016 the comet will have passed 0.72 AU (67,000,000 mi) from Earth and should be around magnitude 6, located in the constellation of Ursa Major.

This comet is dynamically new. It came from the Oort cloud with a loosely bound chaotic orbit that was easily perturbed by galactic tides and passing stars. Before entering the planetary region, C/2013 US10 had an orbital period of several million years. After leaving the planetary region, it will be on an ejection trajectory. [Source: Wikipedia]

The image was captured with my TMB80ss refractor, mounted on the venerable Meade 12"LX200. The imaging camera was the Canon 450DXsi, at F6.3 (native 504mm FL). Subs were taken around 0C, and 3 minutes each.

Image -- 48 subs at 180sec (2.40 hr) on Jan 10th.

Processing was done with PixInsight, following Harry's tutorial for Comet processing. North is up, and this is a medium crop due to the sizable northern motion of the comet during acquisition . As can be seen there is still some vertical smearing (rain like effect) in the background. All in all, not a bad first time on a comet.

Meanwhile, my ATIK 383L+mono is back from the U.K. after being reconditioned. So this is likely the last image I'll do with the old Canon.