EXERCISE 28 — AZIMUTH SUN (Numerical Solution)

4. On 30^th April 2008, in DR 00˚ 00’ 060˚ 12’W, the sun bore 080˚(C) when the GPS clock showed 11h 00m 52s. If the variation was 1˚W, find the deviation of the compass.

d      h       m      s

GMT                   30      11     00     52
LIT (W)                (-)      04     00    48
LMT                    30     07     00     04

GMT  30 April 11h 00m 52s

GHA (30d 11h)            345˚  42.5’                              Dec         N  14˚  57.8’
Incr. (00m 52s)         000˚  13.0’                              d(+0.7)              00.0’
GHA                           345˚  55.5’                                Dec         N  14˚  57.8’
Long (W)                (-)060˚  12.0’
LHA                           285˚  43.5’                                   Lat            00˚  00’

We know that :

P = (360˚ – LHA)
= (360˚ – 285˚  43.5’)
= 74˚  16.5’

Azimuth = N 74.5˚E
T Az          = 074.5˚ (T)
C Az          = 080.0˚ (C)
Error         = 5.5˚ W
Variation  = 01˚ W
Deviation = 4.5˚ W