🔍 Key Concepts

• Azimuth of the Sun by amplitude vs. by altitude – which one applies when the Sun is just above the visible horizon? • Relationship between true bearing, variation, deviation, and compass bearing (TVMDC). • How to apply a chronometer correction to get the correct UTC for entering the Nautical Almanac.

💭 Think About

• First, decide what kind of observation this is: are you using the Sun’s rising/setting point on the horizon, or its vertical angle (altitude)? How does “two‑thirds of a diameter above the visible horizon” guide you? • Work from the observed bearing on the standard compass to find the true bearing of the Sun at that instant, using sight reduction or table methods. Then relate true bearing to compass bearing using TVMDC. • Think carefully about the sign convention: if you go from true to compass through variation and deviation, in which direction (E or W) would the deviation need to be to make the compass heading match what you observed?

✅ Before You Answer

• Verify the correct UTC by applying the chronometer error (slow/fast) with the right sign before taking data from the Nautical Almanac. • Check the local zone description (ZD) for Texas City / central Gulf of Mexico on 8 November to convert between ZT and UTC correctly. • When you apply TVMDC, confirm whether you are solving for deviation = (magnetic bearing – compass bearing) or some other relation, and keep track of the E/W signs carefully.