What is the major advantage of high altitude...

🔍 Key Concepts

• High altitude observations in celestial navigation and how they affect the geometry of lines of position (LOPs) • How sextant altitude corrections (index error, dip, semidiameter, parallax, refraction) depend on altitude • How the azimuth of a celestial body changes with time at different altitudes

💭 Think About

• Think about what actually changes when the observed altitude of a body is high rather than low: does it change the corrections you apply, or the usefulness of repeated sights? • Consider how quickly the bearing (azimuth) of a star or the Sun changes when it is high in the sky compared to when it is near the horizon—how does that affect your ability to get a good crossing angle between LOPs? • For each option, ask yourself: is this something that depends mainly on the body’s altitude, or is it something that is basically the same at all altitudes?

✅ Before You Answer

• Check which corrections (like semidiameter and parallax) are applied because of the body’s nature and distance, not mainly its observed altitude. • Verify which choice directly relates to getting more useful position lines from sights taken at different times. • Eliminate any option suggesting that you no longer need standard almanac data (like GHA and declination) just because the altitude is high.

What is the major advantage of high altitude observations?

The semidiameter correction of the sextant altitude is eliminated.

Errors due to unusual parallax are eliminated.

The same body can be used for a fix from observations separated by several minutes.

The declination is the only information needed from the almanac.

🔍 Key Concepts

💭 Think About

✅ Before You Answer