NavList:

Here is  the promised revised form.

gl

Gary LaPook wrote:

I have attached a revised form that carries the azimuth rules used with 
my version of the Bygrave. These are slightly different than the 
original rules with the original Bygrave due to my simplification of the 
scales. I omitted the second set of numbering on both scales, those 
running from 90 to 180, to keep the scales uncluttered. The results are 
the same as a value exceeding 90  will be found at exactly the same 
point on the scales using my method or using Bygrave's. For example, LHA 
150, Hour Angle (H) 150 west on the original Bygrave will be found at 30 
on my version, the same point that is also marked with "150" on the 
original Bygrave. The same thing happens for values on the cosine scale.

The original Bygrave produced azimuths in the range of 0 to 180 and are 
always laid off from the opposite pole while with mine the azimuth is 
determined in the range of 0 to 90 and are laid off from either pole as 
determined by the rules on the form.

Here is a link to my original post:

 http://www.fer3.com/arc/m2.aspx?i=107414&y=200902

(Note I made an error in the explanation of the sample problem, the 
declination is 20 north not 14 north. I also used a form for the 
illustration using Byrave's "y" instead of my "W".)

Due to my simplified scales I introduced on additional intermediate 
value "X" and, for clarity's sake, I replaced Bygrave's lower case "y" 
with "W". Then using "W" with "X" I derive a "Y" in restricted to the 
range of 0 to 90. Using my method computes the same values as when using 
the original Bygrave.

Notice that "X" determines the final Zn. If "X" exceeds 90 then Zn is 
laid off from the nearer pole and from the far pole when "X" is less 
than 90.

Here is a link to the Bygrave manual:

http://www.fer3.com/arc/img/107419.bygrave-manual.pdf

gl




Paul Hirose wrote:
  

Regarding the Bygrave simulation, it can be done if I know the rules. 
For instance, azimuth is obtained by taking an arctangent, but that 
function yields a result between -90 and +90. There must be some rule to 
convert that to the range 0 to 360.

  
    

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