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True North in One Sentence (again)

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Subject: True North in One Sentence (again)
From: (John Brosnahan)
Date: Tue, 07 Jan 1997 10:12:19 -0600
>I live in a location where the takeoff angle to horizon to the east is
>virtually zero degrees, in other words, straight out.  To the west the
>horizon is blocked by tall mountains and the takeoff angle is probably 20
>degrees.  Will this make a difference to the sunrise and sunset times.?
>Don't flatlanders have it easy!

Of course it makes a difference in time if you go out and observe the
sunrise and sunset and your horizon is different in one direction than 
the other (although you could compensate for it).  But the programs 
on your DX packet cluster and other, readily available ones don't know 
your local topography and so they calculate SR/SS based on 0 deg 
horizon. Your local newspaper (and TV newscasts) SR/SS times are
also based on 0 deg horizon calculations as well.  Of course, the 
accuracy of true north determination when using newspaper or TV 
SR/SS times is a function of your distance (and bearing) from the 
place for where they do the calculations

The North Shadow program in the 97 Handbook calculates the local 
time for the sun to cast a true north (or south) shadow without reference
to your local topography, as well.

73 John  W0UN

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