Comet C/2013 R1 (Lovejoy)

Lately, comet ISON has been getting a lot of attention in the press and among astronomers, but at present it is difficult to see because it is close to the horizon just before dawn. Comet C/2013 R1 (Lovejoy), however, is considerably higher up in the early morning sky at my latitude.  It reached naked eye visibility in early November.

Comets are named using a convention that indicates the type of comet, and the year, half-month and order in which it was discovered. The discoverer's name is often included, and is sometimes used as the familiar name for the comet. This comet was discovered in September 2013 by famous amateur astronomer Terry Lovejoy. It is a long-period comet, with an estimated orbital period of over 10,000 years.

I made these images early in the morning on November 13. The first is a stack made in RegiStax 5 of 16 two-minute exposures centered on the comet core. The comet was moving rather quickly, so over time it moved a significant distance within my camera's field of view. As a result, aligning the images on the comet core caused the stars to trail.

Comet C2013 R1 (Lovejoy); ST80 on Vixen SP; EOS Rebel T3; 16x120 at ISO-1600

The second image is a combined stack of four images using the comet stacking settings in Deep Sky Stacker. The program attempts to stack the comet and stars separately, then combine them.

It did a fair job of producing the image, but it washed out the color of the comet and left "holes" in the brighter stars. After a bit of work I got most of the color back and fixed the stars.

Although it does not have the detail of the first image, it looks better than a single frame.

4x120 at ISO-1600, stacked in DSS using the "Comet and stars" stacking mode.