Comet 46P / Wirtanen has been an exciting comet this year, making the holiday season a little brighter for amateur astronomers.
I was able to finally image this comet on December 11th, and produced a very interesting timelapse movie, showing its rapid progress against the stars. The combination of all the frames of this data produced this image.
A fast moving comet provides quite a challenge for the astrophotographer. You have a choice to align the subrames on the stars (in which the comet smears into a long hazy line), or to align on the comet head (this allows the comet to be images larger and as a focussed point of light, but the stars trail in the image.
The solution is to do both and combine them afterwards in a layered manner. That is the process that produced the image above: a large cometary coma against a background of pinpoint stars.
Canon 60D with an Astronomik CLS filter, at the prime focus of the KPO 18″ Reflector. Star field: 11 x 60s subframes. Comet coma: 76 x 60s subframes, all taken at ISO 1600. Layered in Photoshop.
Click on the image to see a larger version.