Saturday was clear and the forecast for the evening was good so I started looking at Cartes Du Ciel for possible targets for the 20″. Low in the East is generally best for this system and fitting the bill perfectly was a comet, C2009/P1 (Garradd). Brightness was shown as mag 8.8 which is fairly bright as well.
The plan was to take multiple LRGB sequences with the Atik 383, each exposure being 60 seconds. Then stack on the comet and remove the stars from the image, stack on the stars and remove the comet and finally combine the images. Due to the comet’s motion across the sky, this complex procedure is required to avoid trailing of either the comet or stars.
There were some problems with the altitude drive which resulted in a fair few frames being rejected but, after a couple of runs through Photoshop trying different techniques, here is the result.
