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[TowerTalk] beam headings

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Subject: [TowerTalk] beam headings
From: (Earl W Cunningham)
Date: Wed, 09 Jul 1997 01:37:31 EDT
Gerald's (K5GW) comments about rapid azimuth changes of the sun during
solar noon are well-taken.  I used to experience this phenomenon in the
old "spy-in-the-sky" days when I operated a satellite tracking station in
the Aleutians (does anyone remember me as KL7FRY in 1966-67?).  We
tracked the satellites with a manually-controlled (joystick) antenna.  On
near-overhead passes, it was nigh impossible to follow the bird using the
azimuth and elevation indicators, due to the extremely rapid changes in
azimuth.  This was not because the bird was moving across the sky any
faster, but rather due to the apparent mechanical restrictions on the
az-el operation of the antenna.

   When an object passes directly overhead in an east-to-west direction,
its azimuth very abruptly goes from 90 to 270 degrees.  Non-overhead, but
high-elevation passes exhibit this same phenomenon to a lesser extent.

   In summary, old Sol is not "moving" any faster at solar noon than at
any other time.  His position in the sky still changes by about 1/4
degree/minute, regardless of his azimuth change!!

   For those who still feel they need split-second accuracy, I have
available a program which computes solar noon for any QTH with printouts
in HH:MM:SS.

   73, de Earl, K6SE

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