DAVIS Mark 3 Sextant - Manual (Page 12)

Page 10
Presentations shown here are commonly used by navigators to help insure the
accuracy of their calculations:
Figure 13 Figure 14
Longitude Diagram
(view of earth looking at
the South Pole)
Latitude Diagram
(view of earth looking at
the Equator)
Figure 14
Position plot
on a chart.
SYSTEMS OF CELESTIAL NAVIGATION
The method described above for calculating your position is the oldest method
used since the introductions of the chronometer. Please note the following:
1. Latitude may be determined at noon if you know the corrected altitude of the
sun and its declination. You need not know the time. The accuracy of your cal-
culation is limited only by the accuracy of measurement of the sun’s altitude
and by the accuracy of the declination tables.
2. To determine longitude, you must know both the time of observation and the
equation of time. While your sextant gives highly accurate measurements, prac-
tical difficulties inherent in this method normally preclude accuracy of more
than 10' of longitude.