How would you tell the cardinal points ?

[Externet]

Hi all.
To setup a sun tracker positioned as exactly as possible in-line to true east-west...
A compass is not accurate enough, specially with the declination variances. How would you find the cardinal points ?
Say you are in a backyard, fences are not aligned to anything, and you want to nail a string W<-----> E to ± 1º from one fence to another.
Ahhh... it's cloudy.

Setec... Is this one for your expertise ?

Miguel

[SETEC_Astronomy]

Would any of these methods work for you? East - West Without A Compass

I slightly remember a process similar to the ones linked that was extremely accurate and proposed to be the method used by ancient Egyptians to align the pyramids. The full details escape me now though.

[CeaSaR]

Here's a couple of other ways to do so with a compass:
GeoMagnetic Maps
USGS Instructions
Follow the steps on these pages and you should be able to adjust your compass to the local magnetic deviation.

CeaSaR

[jwax]

Got Google Earth? When you go to the measuring stick function, you'll get an azimuth reading as well as distance when you stretch a line across your yard.
Then, note some landmarks like buildings to find due east/west.