Question 1878Navigation General

The correct answer is A) 090°. To determine the longitude of a vessel, you need to observe a celestial body on a bearing of 90° (East or West) relative to the vessel's course. This is because when the celestial body is observed on a bearing of 90°, it will be at its highest or lowest point in the sky, which is known as the meridian passage. By observing the time of the meridian passage and knowing the body's celestial coordinates, you can calculate the vessel's longitude. The other options are incorrect because observing a celestial body on a bearing of 180° (South), 241° (West), or 061° (Northeast) would not provide the necessary information to determine the vessel's longitude.