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- The purpose of determining the Magnetic Declination is to identify the True North true north for the site. Note that a positive declination is east, while a negative declination is a west.
- Run Google Earth
- Type Lake Okeechobee in the search box then selects select the "Enter" key on the keyboard.
- On the toolbar of Google Earth, left mouse click on Tools > Options > Apply > OK. Figure 1 and Figure 2 show this process.
- Add a temporary place-mark (see Figure 3) to so we can get the coordinate of the place-mark
- Open USGS Web Calculator: http://ngdc.noaa.gov/geomag-web/ ( see Figure 4).
- Copy and paste coordinates of the place-mark into the USGS web calculator. Note that select S/N and W/E accurately (see Figure 5 ) then left mouse click on Calculate button.
- The result of Magnetic Declination is displayed in Figure 6.
- Go back the Google Earth, enter the Magnetic Declination 6.26oW (W means that the declination here is negative) on the heading of the place-mark. (see Figure 7) then LMC the OK button. We will see that the background image on Google Earth will rotate from the west to the east with an angle of 6.26o.
- After the background image points to the true north correctly we can delete the temporary place-mark by RMC on place-mark then select Delete option.
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