Jump to content

Novice Challenge

Zeta Cancri with ED80?

Recommended Posts

Has anyone successfully split Zeta Cancri (Tegmine) into 3 components with an ED80 or similar?  Easy enough to see 2 components but tonight with Cancer well placed and a reasonably steady sky the tighter pair at times looked elongated but not split. I was using 240x which is very high power indeed with an 80mm but I’ve always found that doubles take much higher powers than most other objects.

My favourite triple Beta Mon was a treat at 240x with my ED80 and LV 2.5mm

with my 6”:and 10” Dobs Tegmine splits into 3 as long as the conditions are reasonable.

  • Like 1
Link to comment
Share on other sites

With 80mm the airy disc diameter is about 1.7 arcseconds in green light (a bit larger in red and a bit smaller in blue). So at best you can see an elongation, as this simulation suggests:


Well done for spotting it with your 80ED! My seeing was relatively poor and I couldn't use more than x120 in my 102mm ED last night. The smallest aperture I've seen the third close component of Tegmine is my 127 Mak at about x250 and it was not a clean split. By contrast my 180 Mak makes it almost easy on a good night but that is more than twice the aperture.

Edited by Nik271
  • Thanks 1
Link to comment
Share on other sites

@NGC 1502 I took this through my ED80 tonight. Lucky imaging with stacking (seeing was ok). A clear split between the AB pair and C component, but only elongation of the AB pair (which is to be expected given their separation). 


  • Like 1
Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    • No registered users viewing this page.
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. By using this site, you agree to our Terms of Use.