Copeland’s septet (Hickson 57)
Contained in about 6 arc-minute area are seven galaxies to challenge those with large aperature scopes and dark skies (or Stellacams from light polluted backyards). I didn’t have the gamma set correctly set on the Stellacam when I took these. I’m learning that the gamma setting needs to be on medium for faint objects — if it is off there is not much to stack. There should be more detail, I’m going to visit this object again soon. Image taken last evening, April 20 just after midnignt with Nexstar11 telescope, Meade F3.3 focal reducer, and Stellacam2 video camera, gain 9/14, gamma off (unfortuantely), and integrate at 256.
April 21st, 2006 at 11:25 am
I’ll see if I can image this with a DSLR…Probably not but,it is worth a try!!!.
April 21st, 2006 at 2:02 pm
I get dark sky envy when I see all these images of galaxies. Great grabs.
I am not familiar with how the stellacam works. Do these shots require a motorized equatorial mount and long exposure times? Could one use a Stellacam on non-motorized and then stack images?
peter
April 21st, 2006 at 3:35 pm
The longest time the Stellacam2 can expose is about 8.5 seconds. The 8.5 second exposures can be stacked to decrease noise. I typically image an object for about 20 minutes, so I take about 150 images in that time. With Registax3 I then use the “rotation” button to align the images and eliminate any rotation which might result from having the equatorial mount not exactly north.
As I recall, there was a very slight amount of rotation evident with a motor driven alta-azimuth mount with 8.5 second exposures. However, you can get just about as deep with only 4 second exposures. I often switch to 4 second exposure (occasionally 2 second) if its a bit breezy. I think you should be able to get very good images on an alti-azimuth mount if it was solidly built.
The Stellacam2 is an amazing device — with my 11 inch Nexstar I can get to nearly 17th magnitude here in a light polluted Denver suburb. That is as visually deep as a 30 inch can go at a dark sky site! Not as much resolution, a 30 inch is still preferred — looking at a notebook screen is not the same as looking though an eyepiece.