Handbook of Magnetic Compass Adjustment - Maritime Safety ...

An illustration of a curve of magnetic azimuths of the sun is shown in figure 808. This curve is for the period 0700-0900
zone time on May 31, 1975, at latitude 23°09.5'N, longitude 82°24.1'W. The variation in this area is 2°47'E. At the midtime,
the meridian angle of the sun is 66°47.23', and the declination is 21°52.3'N. Azimuths were computed at half-hour intervals,
as follows:
Zone time Meridian angle Declination Latitude Magnetic azimuth
0700 81°47.1'E (5h 27.1m E) 21.9°N 23.2°N 069°39'
0730 74°17.1'E (4h 57.1m E) 21.9°N 23.2°N 071°57'
0800 66°47.2'E (4h 27.1m E) 21.9°N 23.2°N 074°06'
0830 59°17.2'E (3h 57.1m E) 21.9°N 23.2°N 076°08'
0900 51°47.2'E (3h 27.1m E) 21.9°N 23.2°N 078°07'
This curve was constructed on the assumption that the vessel would remain in approximately the same location during the
period of adjustment and swing. If the position changes materially, this should be considered in the computation.
Figure 808 – Curve of magnetic azimuths
Extreme care must be exercised when using the sun between 1100 and 1300 LMT, since the azimuth changes very rapidly
during this time and the sun is generally at a high altitude.
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