Section 1. Preparation and Siting

Subtract declination from 360°

Add declination to 0°

22 E

20 W

18 W

16 W

20 E

18 E

14 W

12 W

16 E

10 W

8 W

14 E

6 W

4 W

2 W

12 E

 

0

10 E

 

2 E

 

4 E

8 E

6 E

 

FIGURE 1.4-1. Magnetic Declination for the Contiguous United States

1.4.1 NSSDC CGM Service

The NSSDC CGM (Corrected Geomagnetic) Service provides an easy way of determining magnetic declination of a specific site. Since magnetic declination fluctuates with time, it should be determined each time the wind vane orientation is adjusted. It can be accessed on the world wide web at

http://nssdc.gsfc.nasa.gov/space/cgm/cgm.html

If you know the latitude and longitude of your site, fill out Form 1as shown below for an accurate magnetic declination. If you do not know the latitude and longitude of your site, fill out Form 2 for estimate of magnetic declination. Note that longitude is expressed in 0 to 360 degrees east of the Greenwich prime meridian, and that north latitudes are positive.

Query Form 1: Latitude/Longitude

Latitude/Longitude below specified in: Geographic

Year (from 1945 to 2000): 1998

Altitude above Earth's surface (km) [from 0. to 40000.]: 0

Latitude (degrees) [from -90.00 to 90.00]: 42.03

Longitude (degrees) [from 0.00 to 360.00]: 248.15

Query Form 2: Image Map

Year (from 1945 to 2000): 1998

Altitude above Earth's surface (km) [0. - 40000.]: 0

Click on map to specify location and submit: (select area on map provided)

A table containing similar information to the following will be returned after submitting Forms 1 or 2.

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