Re: [ATM] The best time to Foucault?

["Dave Tabor" <david@tabor.com>]

Hi,
Good call Richard.  I typo'd that one.  So much for using the windows 
calculator & my mouse.
So, there is really only about .1 magnitudes difference.
Thanks for catching that one.
- Dave


----- Original Message ----- 
From: "Richard F.L.R. Snashall" <rflrs@rcn.com>
To: "Dave Tabor" <david@tabor.com>
Sent: Monday, October 16, 2006 10:46 AM
Subject: Re: [ATM] The best time to Foucault?


> Dave Tabor wrote:
>>
>> MASKED (and still ignoring the beveled edge loss):
>> If I masked 5%, just less than 1/4 inch all the way around, I would now 
>> have a 7.6" mirror and the mirror would be 181 square inches. 
>> Subtracting the same secondary, it's now 174 square inches of light 
>> gathering.
>> Limiting magnitude 7.5 + 5 LOG (19.30 cm aperture) = 11.90
> I cannot confirm this.  I get 13.93. 

_______________________________________________
ATM mailing list http://www.atmlist.net/