Then I saw it, now I don't
Posted 03 November 2013 - 08:10 PM
In a recent thread, I related how I had split Delta Cygni with relative ease.
Imagine my surprise when last night I tried to split Delta Cygni again -- same scope, same eyepieces -- and could not detect the companion! A cold front moved through the area two nights ago so the seeing is much, much worse.
Moreover, the star was moving around in the field of view! I'm not used to using such high magnifications, so this affect of bad seeing was fascinating to view.
While this may seem obvious to many, this past night gave me a wonderful introduction to how seeing really matters on close pairs!
Posted 03 November 2013 - 09:04 PM
I have seen that rapidly jumping star image, it's pretty prevalent in modest apertures due to some larger scale atmospheric tilt component during modest seeing - rapidly changing the apparent position of the image. Otherwise, the images stays pretty much intact depending on aperture and the severity of smaller scale seeing. It just bounces around a lot. If I understand it, that's the same property that begins to make larger instruments break into a speckle pattern while smaller apertures still enjoy some semblance of better seeing.
Posted 03 November 2013 - 09:46 PM
Posted 04 November 2013 - 04:22 PM
Posted 04 November 2013 - 08:36 PM
The one time I tried with my 70mm I didn't have a chance in spit - the seeing was 4 Pickering and it just wouldn't allow even a passing mirage to pop through. I would like to bag it with that scope though.
Posted 05 November 2013 - 05:10 PM
I really enjoy using minimum aperture to obtain results on double stars. Why? Because the star images are so pure and less affected by seeing conditions. Additionally small telescopes are easy to setup and takedown. I'm sure your Ranger can split Delta Cyg if conditions are right. Bill