# What is agonic line in surveying?

## What is agonic line in surveying?

: an imaginary line on the earth’s surface connecting the north and south magnetic poles and passing through those points where there is no magnetic declination and where a freely suspended magnetic needle indicates true north — compare aclinic line, isogonic line.

## Where is the agonic line in Canada?

Ellesmere Island
Since its discovery in 1831, the MNP has been around (yes, it moves) Ellesmere Island in Northern Canada, about 500 miles (800 kilometers) from the GNP. However, there are points on the surface of the earth where the compass needle lines up with both MNP and, beyond it, GNP.

What does the agonic line represent?

an imaginary line on the surface of the earth connecting all points at which the declination of the magnetic field of the earth is zero.

What is Isogonic and Agonic lines?

Isogonic lines are lines on the Earth’s surface along which the declination has the same constant value, and lines along which the declination is zero are called agonic lines. The lowercase Greek letter δ (delta) is frequently used as the symbol for magnetic declination.

### Where does the magnetic needle point east of the agonic line?

At points east of the agonic line, a magnetic needle will point west of true north (negative declination). There is a pattern, but it does not follow meridians or parallels. Isogonic lines are like magnetic contour lines – they trace a path of constant magnetic declination.

### When do you use An agonic line on a chart?

These lines are called “isogonic lines” unless it is indicating a zero variation, then it is called an ” agonic line .” A pilot uses these lines to correct the true course he drew on a chart for variation. Mag course mismatches: how many direct magnetic courses can there be between two points? Sometimes the answer is three.

When is An agonic line called an isogonic line?

There’s always someone who doesn ‘t get the word These lines are called “isogonic lines” unless it is indicating a zero variation, then it is called an ” agonic line .” A pilot uses these lines to correct the true course he drew on a chart for variation.