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## True North in One Sentence (again)

 To: True North in One Sentence (again) broz@csn.net (John Brosnahan) 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 -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: K7LXC@contesting.com Sponsored by Akorn Access, Inc & KM9P ```
 Current Thread True North in One Sentence (again), Dean Norris True North in One Sentence (again), Bill Hider True North in One Sentence (again), John Brosnahan <= True North in One Sentence (again), Bill Coleman AA4LR True North in One Sentence (again), Chad Kurszewski WE9V True North in One Sentence (again), Jay Terleski