Celestial Exercise for Part 14: A complete Twilight Planning and Shooting
15 November 2021 · 1h 17m · 1K views · Madeira to Canary Islands
What this video covers
Celestial navigation planning and execution for a morning twilight shot requires calculating the timing of nautical and civil twilight based on the vessel's latitude and longitude. For a position at 30° 14' N, 14° 15' W on October 15, the navigator determines the time difference between the meridian and the vessel's position to establish the UTC window for observations.1:43 Using the Nautical Almanac, the navigator identifies Venus as the primary planet for the morning shot, noting its rise time and approximate azimuth.8:46 The process involves using planning templates to estimate the local hour angle (LHA) of Aries and selected stars like Regulus and Aldebaran, allowing for simultaneous observation planning.3:05 The navigator accounts for a 2-minute index error and a 3-meter height of eye, then performs the final reduction for the planet and stars using the LHA and declination.33:08 Plotting the resulting lines of position on a chart provides the final fix.1:15:54 Calculating twilight times and LHA in parallel streamlines the workflow for multiple celestial bodies.
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