On 8 November your 1731 zone time DR position is LAT 27°16.0'N, LONG 137°25.0'W. Considering their magnitude, azimuth, and altitude, which group includes the three stars best suited for a fix at star time?
• Star selection for a three-star fix (separation in azimuth and altitude) • Using DR position, LHA Aries, and the Air Almanac to find suitable stars • Avoiding stars that are too low or too high in altitude for accurate sights
• From your DR position and date/time, roughly which part of the sky will have bright, navigational stars well spread around the horizon? • Which group seems to give you stars that are separated by at least about 30°–60° in azimuth and have mid-range altitudes (not near zenith, not near the horizon)? • Think about which stars are even likely to be visible at that latitude and local time in early November.
• Verify azimuth spread: the three stars should not be all on the same side of the sky; you want them roughly spread to improve geometry of the fix. • Check altitudes: avoid stars whose computed altitudes are very low (near 15° or lower) or very high (above ~75°), as they are less desirable for a precise fix. • Confirm brightness and identifiability: all three should be first-magnitude (or strong second-magnitude) navigational stars that are easily recognized.
No comments yet
Be the first to share your thoughts!