🔍 Key Concepts

• Chronometer correction and converting chronometer time to Greenwich Mean Time (GMT/UT1) • Using DR position, time, and altitude (Ho) to select the most likely star from a list using a Nautical Almanac/star tables • Checking that the true bearing and altitude make sense for that star from the given latitude/longitude and date

💭 Think About

• First, apply the chronometer error (fast/slow) to find the correct GMT of the sight. How does this time compare to evening/morning twilight at your DR position on 22 April? • From your DR latitude 23°54.5'N and the star’s observed bearing 248°T (about west-southwest), what approximate declination (north/south of the equator) would you expect the star to have? • Compare which of the listed stars would be visible at about 25° altitude in that direction at that time and date for this latitude. Which stars are even above the horizon there?

✅ Before You Answer

• Be sure you applied the chronometer correction in the correct direction (fast vs. slow). • Verify whether each star choice is north or south of the celestial equator, and whether that matches the expected sky area from 24°N latitude on that bearing. • Check if the Local Hour Angle (LHA) and declination for each candidate on 22 April at the computed GMT would place the star near 25° altitude and bearing 248°T from the DR position.