Got up at 3:30 this morning to image Comet Catalina passing close to M101 (the Pinwheel Galaxy). First light for my kit in a while due to the terrible run of whether we've been having, and first legs for my astronomical longjohns, which did their job of keeping my legs warm. The above image was taken using a vintage 135mm lens and modded Canon 1100D camera, it's 14 minutes exposure time in total.
The comet is displaying two distinct tails, a wide dust trail pointing up and a fainter, narrower ion tail to the left. The dust is left behind in the wake of the comet's orbit, while the ion tail points away from the Sun as it more strongly affected by the solar wind. M101 is a spiral galaxy similar in size to our own Milky Way. Above and to its right a faint smudge is visible. This is another galaxy, a satellite of the Pinwheel that has been disrupted by its gravity, NGC 5474.
Comet Catalina C/2013 US10 makes its closest approach to Earth tomorrow, the 17th January. By coincidence it also makes its closest pass to M101 on the same date. Hopefully the weather will be kind and some astrophotographers will be able to capture it at higher magnification than I could manage with my mid-telephoto lens. There will never be another opportunity to image this particular comet. After making its closest approach to the Sun on the 15th November it is heading back out of the solar system and will escape into interstellar space.