Convert grid azimuths to back azimuths

Plot back azimuths Determine location on a topographical map

This Web course consists of four lessons and four student activities Lesson 1 - Determine magnetic azimuths using a lensatic compass. Lesson 2 - Convert magnetic azimuths to grid azimuths. Lesson 3 - Convert grid azimuths to back azimuths. Lesson 4 - Plot back azimuths and determine location on a topographical map

You have done the first three of the four steps in locating yourself on a topographical map. You have located two distant known points. You have converted their magnetic direction to a grid (or map) direction. You know the direction to them but not to your location. Now that you have learned to convert the grid azimuths to back azimuths you are ready to finish up. This lesson helps you understand how to plot the back azimuths. The two or three back azimuths will intersect at a location on the map. Where they intersect is your location (X marks the spot). Orient the map toward the North using the compass. Identify two or three known distant locations on the ground and mark them on the map. Measure the magnetic azimuth to the first of the two or three known positions from your location using a compass (lesson 1). Convert the magnetic azimuth to a grid azimuth (lesson 2). Convert the grid azimuth to a back azimuth (lesson 3). Using a protractor, draw the back azimuth on the map from the known distant position back toward your unknown position. Repeat the steps in blue for a second and optional third known distant position. The intersection of the lines is your location.