Which resource lists star positions and time data to guide calculations?

Which resource lists star positions and time data to guide calculations?

• A. Log tables and ephemerides
• B. Astrolabe
• C. Sextant
• D. Magnetic compass

Answer: (A)

In celestial navigation, you need to know where stars are at specific times in order to turn a sight into a meaningful calculation. Ephemerides are the authoritative tables that list those star positions for given dates and times. Log tables then help you do the math quickly and accurately as you process the sight data. Together, they provide the essential data and the calculation framework needed to determine your position. The other items are measurement tools or instruments: an astrolabe and a sextant are used to measure angles, not to supply star coordinates or time data, and a magnetic compass gives direction rather than star positions or times.

In celestial navigation, you need to know where stars are at specific times in order to turn a sight into a meaningful calculation. Ephemerides are the authoritative tables that list those star positions for given dates and times. Log tables then help you do the math quickly and accurately as you process the sight data. Together, they provide the essential data and the calculation framework needed to determine your position.

The other items are measurement tools or instruments: an astrolabe and a sextant are used to measure angles, not to supply star coordinates or time data, and a magnetic compass gives direction rather than star positions or times.