On 22 May your 0437 DR position is LAT 25°...

Question 1 of 2707066636eea28f7522a1c51ad12

On 22 May your 0437 DR position is LAT 25° 18.5' N, LONG 51° 18.0' W. You observe an unidentified star bearing 142° T at an observed altitude (Ho) of 23° 10.2'. The chronometer reads 07h 40m 40s, and is 03m 24s fast. What star did you observe?

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Question 1 of 27070

🔍 Key Concepts

• Using the chronometer correction (fast/slow) to find the correct UTC of the sight • Relating DR position, true bearing, and observed altitude (Ho) to where the star must be on the sky (azimuth and approximate declination) • Using a star identification table or star finder (e.g., based on GHA/Dec at the sight time) to match the observed data to a specific star

💭 Think About

• First, correct the chronometer time and determine the exact UTC of the observation. How does a "+fast" chronometer affect the true time? • From the DR latitude and the observed altitude, would you expect the star to have a declination north or south of the equator? Roughly how large? • Given the true bearing (azimuth) toward the SE and the time of year (late May), which of the listed stars is most likely to be visible in that part of the sky with that altitude and declination?

✅ Before You Answer

• Be sure you apply the chronometer correction in the correct direction (fast vs slow) before using any sight reduction or star ID tables. • Check whether each candidate star’s declination (north or south, and approximate value) could produce an Ho near 23° from latitude 25° N on a SE bearing. • Confirm that the star you choose would be above the horizon at that GMT and date for a vessel near 25° N, 51° W.