🔍 Key Concepts
• Local time vs. UTC (GMT) conversion using zone description (ZD) to get correct GHA and declination from the Nautical Almanac
• How to compute true altitude (Ho) from sextant altitude (Hs), including index correction, height of eye (dip), and other corrections
• Using the assumed position (AP) with calculated altitude (Hc) and local hour angle (LHA) to determine the Sun’s azimuth (Zn) from the sight reduction tables or formulas
💭 Think About
• What is the correct GMT of the sight after applying the chronometer error, and how does that compare to the ZT of the sight using the zone description from your longitude?
• Once you have the Sun’s GHA and declination for the correct time, how do you form LHA and then use Lat, Dec, and LHA to determine whether the Sun is in the NE, SE, SW, or NW quadrant?
• Given your latitude and the Sun’s declination, should you expect an azimuth closer to east, southeast, or south, and how would that help you eliminate some answer choices that don’t fit the geometry of the problem?
✅ Before You Answer
• Be sure you apply index error with the correct sign ("off the arc" vs. "on the arc") when correcting Hs to get Ho.
• Verify you have the correct zone description (ZD) sign for 146° E longitude so that your conversion between ZT and GMT is in the correct direction.
• Double‑check that your final Zn is expressed as a true bearing from 000° to 359°, and that the quadrant (NE/SE/SW/NW) matches the relative position of the Sun based on your AP, declination, and time of day.