EXERCISE 29 — RISING/SETTING AZIMUTH -SUN (Numerical Solution)

NAMING OF AMPLITUDE: The prefix of True Amplitude is E if the body is rising and W if the body is setting. The suffix is same as that of the declination.

T Az          = 288.0˚ (T)
C Az          = 285.0˚  (C)
Error          = 03.0˚ E
Variation   = 02˚ W
Deviation  = 5.0˚E

  1. Jan 20th 2008, in DR 54˚ 20’S 046 ˚ 27’W, the sun set bearing 234˚(C). If variation was 3˚ W, find the deviation of the compass.

LMT Sunrise       = 20d   20h  21m  00s
LIT (W)                   = (+) 03h  05m  48s
GMT Sunset        = 20d   23h  26m  48s

Dec sun  20d  06h            = S 20˚  05.7’
d (-0.5)                               =       –   00.2’
Dec 2d  06h  37m  00s     = S20˚  05.5’

We know that :

e29q3p1

NOTE:

NAMING OF AMPLITUDE: The prefix of True Amplitude is E if the body is rising and W if the body is setting. The suffix is same as that of the declination.

T Az          = 234.0˚ (T)
C Az          = 234.0˚  (C)
Error         = NIL
Variation  = 03˚ W
Deviation = 3.0 W

  1. Nov 30th 2008, the sun rose bearing 110˚(C) in DR 49˚ 18’N 110˚ 12’E at 00h 10m 00schron time. If chron error was 05m 10s SLOW and variation was 10˚E, find the deviation of the compass.

LMT Sunrise   = 30d   07h  35m  00s
LIT (E)                  = (-) 07h  20m  48s
GMT Sunrise      = 30d00h  14m  12s

As we know that:
LMT of Sunrise or Sunset are taken from the nautical almanac and needs only be interpolated and taken in whole minutes of time. If the time ofobservation is given in the problem, then given time should be used for calculation. It is necessary to remove the ambiquity of chron time.

Dec sun  30d  07h             = S 21˚40.0’
d(-0.4)                                 =       –   00.1’
Dec 2d  06h  37m  00s    = S21˚  39.9’

We know that :

e29q4p1

Rising Az = E 34.5˚S
T Az          = 124.5˚ (T)
C Az          = 110.0˚  (C)
Error         = 14.5˚ E
Variation  = 10˚ E
Deviation = 4.5˚E

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