Section 1. Preparation and Siting

Geographic

Alt.

CGM

IGRF Magnetic Field

Dipole

Lat.

Long.

(km)

Lat.

Long.

H(nT)

D(deg)

Z(nt)

Lat.

Long.

42.03

248.15

0.

49.80

311.06

20608.

14.417

50505.

49.68

312.14

Magnetic declination is bold in this example to show its location in the table. A positive declination is east, while a negative declination is west. The declination in this example is 14.417 degrees. As shown in Figure 1.4-1, the declination for Logan, UT is east, so True North for this site is 360 - 14.417, or 345.5 degrees.

FIGURE 1.4-2. Declination Angles East of True North Are

Subtracted From 0 to Get True North

FIGURE 1.4-3. Declination Angles West of True North Are

Added to 0 to Get True North

1-9