Comet Hartley Dives for the Southern Horizon Bright comet in Canis Minor

Uploaded 11/7/10

Select an image size for a larger view: 1290 x 960 1600 x 1200
Select an image size for a larger view: 800 x 600 1290 x 960

 There is no easy way to shoot a speeding bright comet, as it moves up to several degrees per day across the night sky. Here are two representations of the same mornings data, in which the comet moved nearly a third the way across my 3/4 degree wide field during the 45 minutes I was exposing it. The comet is currently a very diffuse extended object, about half a degree in size and beaming softly at 6th magnitude. The strong green coloration is actually a cyan color, from the ionized gas of cyanogen in the comets coma. You can also see a bit of tail here, extending off to the right from the core.

The image on the left panel is the full field of view of the telescope onto the ST10 chip. The comet was exposed for 45 minutes and the data was combined using "Minimum" directly onto the nucleus of the comet in the very first image. Thus this is the position of the comet on the first frame, with extended exposures merged onto its core. This shows a non moving comet on a stationary star field.

The second image is the same data, but by summing the comets nucleus of all the frames to make a time exposure like image. This shows the stars streaked as the comet whizzes by the star field. Unfortunately, the stars colors are not retained well because the color data was taken sequentially and leaves multi color beads in the stars. A one shot color camera would remedy this! Also, the field is half the size. Why? Because the comet moved nearly off the frame during the exposures, so the amount of field around the registered comets head diminished with exposure. So the comet appears twice the size of the image on the left.

Lens: 12.5" f/5 Newtonian Platform: Astrophysics AP1200 Exposure: RGB = 15:15:15 Location: Payson, Arizona Elevation: 5150 ft. Sky: Seeing 8/10, Transparency 8/10 Outside Temperature: 45F Processing Tools: Maxim DL, Photoshop CS2 HOME GALAXIES EMISSION NEBS REFLECTION NEBS COMETS GLOBULARS OPEN CLUST PLANETARIES LINKS