On 10 October your 1500 zone time DR position is LAT 27°35.6' S, LONG 44°49.0' W. You are on course 342°T at a speed of 24 knots. Considering their magnitude, azimuth, and altitude, which group includes the three bodies best suited for a fix at star time?
• Star selection for a fix: prefer bright stars well spread in azimuth, not too low or too high in altitude • Magnitude and body type: planets, Moon, and very bright stars behave differently for star time sights • Geometry of a fix: best accuracy when azimuths differ significantly (good cut angles)
• From the DR position and date, think about which bodies will be above the horizon and not too close to the zenith or horizon around evening star time • Ask yourself which group gives you three bodies that are reasonably separated around the sky, rather than bunched in one sector • Consider which bodies (Moon, Venus, bright stars) are sometimes avoided for precise fixes due to rapid motion or size, and which are typically preferred
• Check which option gives three good, point-like stars versus extended or rapidly moving bodies • Verify that the chosen group offers good azimuth spread (ideally 60°–120° between LOPs) rather than similar bearings • Ensure the likely altitudes are in a moderate range (roughly 15°–75°), not extremely low or nearly overhead
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