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» Online Classroom   »   » Public Discussion of Cel Nav   » LHA

   
Author Topic: LHA
rpadams


 - posted August 14, 2007 07:20 AM      Profile for rpadams           Edit/Delete Post 
For a GP longitude East of an observer's AP, following the rule LHA = GHA + a-Lon, I find the calculated angle differs from the plotted angle (as measured westward from the AP). Am I doing something wrong?
David Burch


 - posted August 15, 2007 06:55 AM      Profile for David Burch           Edit/Delete Post 
We used to have some pictures that help with this, but they have wandered off somewhere. We will make them again and post them here. i think that will help.

As i understand, the question is why does adding the GHA to Lon give you the right distance west of you for the LHA.... back shortly.

From: Starpath, Seattle, WA
David Burch


 - posted August 15, 2007 11:46 AM      Profile for David Burch           Edit/Delete Post 
Here are a couple sketches to consider while we take the time to make nice pictures of them... note that the very crude sketch top right is just the trick we use to remember which way is west when looking down at the pole—just imagine the map of the US showing partly on the side and we then know east from west easily by remembering where California is.

Example 1 is for west longitude, which is fairly easy to picture. The rest are for east longitude, where, as you point out, it becomes harder to picture.

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From: Starpath, Seattle, WA


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