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- The purpose of determining the Magnetic Declination is to identify the True North for the site. Note that a positive declination is east, while a negative declination is west.
- Run Google Earth
- Typie Type Lake Okeechobee in the search box then select "Enter" key on keyboard.
- On the toolbar of Google Earth, left mouse click on Tools/Options/Apply/OK. Geo-reference Map Generation in EE and CVLGrid and Geo-reference Map Generation in EE and CVLGrid show this process.
- Add a temporary placemark ( see Geo-reference Map Generation in EE and CVLGrid) to get coordinate of the placemark
- Open USGS Web Calculator: http://ngdc.noaa.gov/geomag-web/ ( see Geo-reference Map Generation in EE and CVLGrid).
- Copy and paste coordinates of the placemark into the USGS web calculator. Note that select S/N and W/E accurately (see Geo-reference Map Generation in EE and CVLGrid ) then left mouse click on Calculate button.
- Result of Magnetic Declination is displayed in Geo-reference Map Generation in EE and CVLGrid.
- Go back the Google Earth, enter the Magnetic Declination 6.26oW (W mean that the Declination here is negative) on the heading of the placemark. (see Geo-reference Map Generation in EE and CVLGrid) then left mouse click the OK button. We will see that the background image on Google Earth will rotate from the west to the east with an angle 6.26o.
- After the background image points the true north correctly. Now we can delete the temporary placemark by right mouse click on placemark then select Delete option.
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