Re: Nav Light Graphic

"Stealth Pilot" <notransponder@[EMAIL PROTECTED]
> wrote in message 
news:nf8534p4rfqr82kr2k08i6gang0qv7rt4v@[EMAIL PROTECTED]
>
> what is a steradian ??????
>

From Dictionary.com

      steradian  (sti-ra'de-?n)
      A unitless measure of solid angles. A solid angle projecting from
the 
center of a sphere and cutting its surface has a measure of s/r2
steradians, 
where s is the surface area of the sphere cut out by the solid angle, and
r 
is the radius of the sphere. See also radian.


      The American Heritage® Science Dictionary
      Copyright © 2002 by Houghton Mifflin Company.
      Published by Houghton Mifflin Company. All rights reserved.


"steradian." The American Heritage® Science Dictionary. Houghton Mifflin 
Company. 20 May. 2008. <Dictionary.com 
http://dictionary.reference.com/browse/steradian>.


Note that the value is dimensionless.  It is the ratio of the sphere
surface 
to the radius squared.  By using this measure the light output can be 
measured at any distance. It doesn't matter what the shape of the measured

"surface" is - only it's area and the distance from the source.

Gerry