Re: Tech Note 66: Degree of Crowding on Mark IV images

[Chris Albertson <calbertson@logicon.com>]

I don't know if I should be mad a Michael or not.  I was working
on the same kind of simulation.  I couldn't follow Andrew's methods
at all.  My plan was to simply add stars one at a time to a box and
count the number of times the FWHM of two stars would touch,  Micheal
did a more general study and actually saved me from having to do the
work.  Thanks.

I think the answer now is pretty clear.  Even from Tom's house
on any given night he will observe thousands (assume 100 frames
per night and two camers) of unresolved blends where both stars
are well above the detection limit had they just been farther apart.

If we talk about cases were one star in the blend is at the 2.5
sigma limit and the other is at 1 sigma then there will be *many*
more because at the 1 sigma level we will likely get >10,000 stars
per frame.  This answers Tom's direct question where he requires one
star to be brighter than the sky background (by one sigma)

It finally dawned on me that the fact that Tom couldn't see any of
these (even with 400+ examples per frame) is a tautology.  You _can't_
see blends because they are blends.  If you could then they are not
blends.

Stupendous Man wrote:
> 
>   Inspired by Tom's questions and Andrew's calculations, I wrote
> a program to place stars randomly on a CCD and calculate the
> distance to nearest neighbors.  The results are in Tech Note 66:
> 
>      http://a188-L009.rit.edu/tass/technotes/tn0066.html
> 
>   The Note shows results for cases from 1,000 to 9,000 stars
> scatted over an image.
> 
>                                           Michael Richmond

-- 
  Chris Albertson

  calbertson@logicon.com                  Voice: 626-351-0089  x17
  Logicon, Pasadena California            Fax:   626-351-0699