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Re: Compass corrections



When I set up the rotator at school (VA3SFL) I tried a compass,
but found there was too much metal in the vicinity to get a
good fix. So I went for the shadow-at-noon approach. I computed
local noon two different ways: one with a program that came
with the ARRL Handbook, and a quick and dirty approximation
from Toronto's longitude.

The centre of the time zone (North American Eastern) is 75 degrees
west. Toronto is at 79.33 degrees west. Each time zone is nominally
15 degrees wide, so 4.33 degrees is (4.33 / 15) * 60 or 17 minutes
west, making local noon 1317 (this was in the summer). The fancy
Handbook program used a more elaborate approach (modelling the
Earth's elliptical orbit) and said 1321. I sat up on the roof
with a can of bright pink spray paint at the appointed time and
noted that the difference between 1317 and 1321 was smaller than
the amount the antenna array flexed in the breeze...
-- 
Laura Halliday VA3LDH    "Laisse le vent tout emporter..."
Grid: FN03gs                - Foly/Viennet
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