# NavList:

## A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding

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Re: Doing my homework
From: John D. Howard
Date: 2016 Nov 3, 16:52 -0700

Tony,

Thanks for your reply but I think I must clear up something you said.  The form you are using is correct.  When you add GHA to a WEST Longitude you are adding a negative number ie you are subtracting.

LHA + EsLon                  3 d + (-) 66 d 30 m = 3 d - 66 30m = -63 d 30 m.

LHA is always between 0 d and 360 d so you must "normalize" the negative LHA by adding 360 to it.  ( If LHA was 425 d you would subtract 360 )

LHA = -63 d 30 m + 360  = 296 d 30 m            LHA is Greater than 180 so the second rule would be used ie   t = 360 - LHA

t = 360 - 296 d 30 m = 63 d 30 m

Rember LHA does not have a sign and is always 0 to 360.  You must normalize if outside that range.  t has a sign: negative for west or postive for east.

John H.

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