Comet C/2009 P1 Garradd was a visible target last year in the constellation Saggita when I first caught a glimpse of it. It made it's way into the constellation Hercules, and since then has been traveling northward in our skies. It has made it from Hercules, to Draco into the border of Ursa Major where it will continue it's path through the big dipper. Garradd is at a magnitude of 7.5, a distance of 1.35AU (astronomical units which equals the distance from the sun to Earth), and is moving quite fast across the sky. The following image was made using the astronomy freeware Cartes Du Ciel.
On March 17th I was out with my telescope and decided to give imaging Garradd a try after having no success with imaging Mars. The astronomical seeing was quite poor that night, so the magnifications needed for planetary viewing were quite unfavorable. Two days before I was out I had taken notice of where Garradd was, and I aimed my telescope in the exact location it was. After I noticed it wasn't where it was two days ago I decided to check it's location for that night when I realized it had moved quite a bit further than I had expected. It was also quite a bit dimmer than I had expected for it being a magnitude of 7.5, but I knew I had it in my sights. After locking on and tracking I attached the Canon 350D to the telescope for some prime focus shots.
Plotted path of Garradd from March 19 to April 16 of 2012. Click to enlarge.
On March 17th I was out with my telescope and decided to give imaging Garradd a try after having no success with imaging Mars. The astronomical seeing was quite poor that night, so the magnifications needed for planetary viewing were quite unfavorable. Two days before I was out I had taken notice of where Garradd was, and I aimed my telescope in the exact location it was. After I noticed it wasn't where it was two days ago I decided to check it's location for that night when I realized it had moved quite a bit further than I had expected. It was also quite a bit dimmer than I had expected for it being a magnitude of 7.5, but I knew I had it in my sights. After locking on and tracking I attached the Canon 350D to the telescope for some prime focus shots.
C/2009 P1 Garradd. Click to enlarge.
This image is made of 16 30second exposures at ISO 1600, and my telescope is an F5. Also with these images I gathered 10 flat frames, 10 dark frames, and 20 bias frames. I brought all these images into Deep Sky Stacker (a free image stacking program) and stacked them using a comet stacking method. I tried 2 different methods, one resulted in the stars trailing and the comet to be clear due to the comets movement making the stars trail. The second method resulted in the image posted above. Basically what it did was stack the 16 images along with the flats, darks, and bias with the comet as the central point. Then after that it automatically stacked another set with the stars as the central point, which DSS then combined the two together to remove trailing of the comet or the stars.
I spent quite a bit of my time figuring this all out as I'm still new to image stacking, and on top of it all comet stacking is a whole other beast that I unleashed. After stacking and adjusting some of the setting in DSS I did my final post processing work in Gimp including duplicating layers, and layer masks which is also all new to me. All-in-all I'm very pleased with my first comet image.
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