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» Online Classroom   » Tech Support   » Celestial Navigation Course   » Page 11-61, bottom Choosing a-Lon

Author Topic: Page 11-61, bottom Choosing a-Lon
David Burch

 - posted July 24, 2008 02:43 PM      Profile for David Burch           Edit/Delete Post 
The rule for figuring out the degrees part of the a-lon is missing a phrase. Compare to the paragraph following. The first case is for GHA minutes less than 30 and the second paragraph is for GHA minutes greater than 30.

Here is a way to write the Rule given there:

Here is the procedure, given DR-lon° and DR-Lon' as well as GHA° and GHA'.

For example if DR-Lon = 122° 45.6' then DR-Lon° = 122 and DR-Lon' = 45.6

Step 1. Choose a-Lon° = DR-Lon° and choose a-Lon' = GHA'

Step 2. Now look at the difference between DR-Lon and a-Lon. Call this Delta

Step 3. If Delta is less than or equal to 30' you are done. The AP = a-Lon° a-Lon' = DR-Lon° GHA'

Step 4. If Delta is greater than 30', then we need to change a-Lon° by 1°, either up or down according to Step 5.

Step 5. If GHA' is greater than 30, then decrease a-Lon° by 1°, but if GHA' is less than 30, increase a-Lon° by 1°.

From: Starpath, Seattle, WA

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