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Question 1

What is the ideal observation period for star sights?

Answer 1

Halfway from sunrise or sunset to Civil Twilight and hallway from Civil Twilight to Nautical Twilight

Question 2

Criteria to consider for star selection

Answer 2

• Body must be visible (could be obscured by clouds)
• Horizon must be clear to measure the altitude (could be obscured by background light or weather or not attainable because of flat calm sea)
• minimum 3 stars, ideally 4 or more to obtain reliable fix
• With 3 stars, ideal angle of cut is 120°
• With 4 stars we can compensate for random errors (due to atmospherics or quality of horizon)
• 4 stars, choose pairs of opposite stars, one in each quadrant. Gives square cocked hat, we are in the middle, high level or reliability.
• Additional stars on N/S or E/W plane to cross through middle of cocked hat

Question 3

What is the correct order for taking observations?

Answer 3

• From East to West, due to visibility of stars and horizon.
• NE and SE first, NW and SW second