Jump to content


(Deep) Limiting Magnitude Charts?

Recommended Posts

The eternal question: "How DEEP can EEVA get [you]"? ?

Only found one CHART example so far. M67 is moving towards setting. But
useful to have stars to (optimistically) Mag +20! Do you know of others? ? 


Edited by Macavity
  • Like 2
Link to post
Share on other sites
52 minutes ago, Martin Meredith said:

BTW any idea of FOV or which part of the cluster this is? Im struggling to match it up.

Hmmm... Took me quite a while too! My typical frames (8" f/4 Newt + 1/2 inch chip) are
about 30' x 20' without clipping  -- Naturally my original had to be inverted left to right! ?


From then it's a "ruler job"... and I reckon about 10 arc minutes square?
I cropped / enlarged (inverted) my image above to give the chart size:


I suspect I wasn't pushing the Watec 120N+ particulary HARD for an
Open Cluster? Maybe 4 min total exposure? So MAG +17 maybe? ?

Edited by Macavity
Corrected 5 to 10 arc minutes!
  • Thanks 1
Link to post
Share on other sites

Hi Chris, For what it is worth. As we know law of diminishing returns kicks in. So 18" scope might get to approx mag 17, 24" scope about 17.6, 32" scope about 18.2 and to get to mag 22 need a 200" scope. I always feel that my C9/ultrastar operates at about 3x its aperture, equivalent to a 27" scope, so I could expect to get mag 18 stars. This seems to be the case. My various programs do not give me magnitudes beyond mag 17 and I regularly see stars fainter than this which I suspect are mag 18 (maybe fainter) but then there maybe background galaxies being picked up. The technical guys may have more knowledge. Mike

Link to post
Share on other sites

I've dug out an old one. In colour I'm getting the V star = 18.04 in 18 x 10s and in Mono the a = 19.42 in 19 x 10s. I've got a longer stack (not shown) of around 60 x 10s which gets to the b = 20.10. As you say though, without pushing them hard for the purposes of detection its difficult to know.

BTW I think the chart above is the wrong way round, not our shots!







Link to post
Share on other sites

If you Google north polar sequence you should find info on another standard field. 

Regards Andrew 

PS If you Google "AAVSO standard fields" you will get a link to a set of modern accurate field. Note there are no decimal points in the magnitudes as the could be confused with stars.

Edited by andrew s
PS added
Link to post
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.