Hi Roger,

I am looking forward to hearing your presentation and meeting you at the NASS
meeting.  I think Fer has pointed out the need for the negative 1 in your first
equation.  I have not seen before the sunrise angle psi of:

>> Sunrise Path:     Cos psi = Sin l / Cos D

I assume l is L for latitude and psi is the angle with the horizon.  
Interesting.

I have been pondering some thoughts this summer about planes and some way to 
show
on a dial map WHERE the sun is setting by a shadow.  I like the opening screen 
of
the NASS home page that shows the area of daylight on the planet  -- but that is
the computer screen -- I like "real" maps.   Has this been done on a dial?  Fred
Sawyer showed in the Compendium the method Foster used to map TIME around the
world.    Any ideas on this from anyone?

Happy dialing,

Warren Thom  (Lat=41.649N   Long=88.096W) - Chicago

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