The Demystified Astro Navigation Course Unit 2 Self Test

Unit 2 Self Test

Question 1. 

Position: 38^o 15’N. 30^o 38’.3 W,

GHA Sirius: 150^o 15’.4.

What is the LHA?

Question 2. 

Position:  33^o 12’.8S.  70^o 54’.5E,

GHA Sun: 45^o 23’.4

What is the LHA?

Question 3. 

Position:  52^o 42’.45N.  65^o 19’.67E

GHA Moon:  345^o 15’.0

What is the LHA?

Question 4. 

Position:  34^o 28’.45S.   172^o 25’.8W.

GHA Mars:  15^o 30’.0

What is the LHA?

 Solutions

 Q.1. 

Long West,   LHA = GHA – LONG

GHA   = 150^o 15’.4

LONG =  30^o 38’.3W     (-)

LHA   =  119^o 37’.1

Q.2.

Long East, LHA = GHA + LONG

GHA    =  45^o  23’.4

LONG  =  70^o  54’.5E    (+)

LHA    = 116^o   17’.9

 Q.3.

Long East, LHA = GHA + LONG (-360^o ?)

GHA   = 345^o  15’.00

LONG =   65^o  19’.67E.  (+)

LHA   =  410^o 34’.67

360^o 00’.00    (-)

50^o 34’.67

Q.4.

Long West, LHA = GHA – LONG (+360^o ?)

GHA   =      15^o  30’.0

LONG =   –172^o 25’.8W.  (-)

LHA    =  -156^o  55’.8

+360^o  00’.0      (+)

           203^o   04’.2

 Note.  The calculations can be made simpler by converting minutes to fractions of a degree as follows:

To convert minutes to fractions of a degree, divide by 60.

To convert fractions of a degree to minutes, multiply by 60.

The solution to Q.4 now becomes:

GHA   =        15^o.5

LONG =     –172^o.43 W.  (-)

LHA    =     -156^o.93

+360^o. 00       (+)

             203^o. 07

LHA  =     203^o  04’.2

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