Next message: Marc Bernstein: "Re: Nautical Almanac Usage"
Bill,
The table I posted yesterday lists some values of the equation in
question from which you could construct a graph; those values span the
relevant portions of the parameter space in question, although more
points could be added between altitudes of 75 and 90 degrees.
Additional values could be computed using any standard sight reduction
software or using HO 229 to fill in some of the gaps.
Fred
On Oct 22, 2004, at 7:31 PM, Bill wrote:
>> Similar phenomenon occurs when the Sun passes the meridian
>> close to zenith. The graph is now smooth but has a big hump
>> in the middle. Closer to zenith, sharper the hump.
>
> Hence my follow up question about the shape(s) (which would not have
> reached
> you before this posting) of the arc the sun scribes at different times
> of
> the year from a fixed position. The next question would be, what is
> that
> shape(s) from the observers point of view?
>
> If it is a circle, then the "humps" will happen at any point on its arc
> where lines are connected from 3 Hc's 2 minutes apart and be identical
> in
> error. If the shape scribed is a similar to a parabola or ellipse,
> and LAN
> occurs at the the intersection of the long axis and the arc, then I
> indeed
> can indeed visualize how it would be most pronounced at LAN.
>
> As usually, I may be getting one step nailed down, only to miss the
> next
> step that will give me a working visual model.
>
