Left Image: Comet 2009 P1 Garrad on 20/9/2011. Right Image: Comet Garrad on the 22/09/11. Click to embiggen. Comet C/2009 P1 Garrad imaged using the Global-Rent-a-Scope GRAS-05 instrument.
The left image was done from 120sec luminance RGB filers at 1x binning, the right luminance 120 sec 2x binning and RGB 60 secs with 2x binning. Images stretched with FITS-Liberator, aligned and cropped in ImageJ then luminance and RGB channels assembled in the GIMP, with a little contrast enhancement.
Not as good as Rolando Ligustri's image using the same exposure and binning on the GRAS-11 instrument. I still have a lot to learn about colour image processing.