LE2-C5S11T4pg Azimuths

Purpose The purpose of this lesson is to teach you how to determine azimuths.

1. Describe grid north, magnetic north, and true north. 2. Describe when grid north, magnetic north, and true north are used in land navigation. 3. Determine the grid azimuth between two points to within 3 degrees, using a protractor.

4. Plot a grid azimuth using a protractor. 5. Plot a known distance onto a plotted azimuth. 6. Determine the back azimuth between two points. 7. Determine the G-M angle, given a declination diagram.

8. Convert a grid azimuth to a magnetic azimuth, using the declination diagram. 9. Convert a magnetic azimuth to a grid azimuth, using the declination diagram. 10. Use the acronym LARS to convert grid azimuths and magnetic azimuths using a declination diagram, when a conversion note is unavailiable.

CPS Key Word Questions (1-4)

 Azimuth  True north  _______ - an angle measured in a clockwise direction from a predetermined baseline.  _________ - a line from any point on the earth’s surface to the North Pole.

 Magnetic north  Grid north  _____________ - a magnetic field that is close to the North Pole. The direction to this north magnetic pole is indicated by the north- seeking arrow of your lensatic compass. _________ - this base line is established by using the vertical grid lines on the map. Grid north may be symbolized on the declination diagram by the letters GN.

CPS Lesson Questions (1-2)

How much do you already know about calculating an azimuth? A.Expert – I could teach this class! B.Advanced – I have done this a few times. C.Basic – I know only the basic tools and rules. D.Novice – What is an azimuth?!

True or False: An azimuth is an angle, but is not part of a circle. A.True B.False

List 2-3 ways you already know how to navigate on land. (Use CPS “Pick a Student” for this question)

An azimuth is an angle, which means that it is part of a circle.

 True north can be found at night by locating the North Star.  Magnetic North is indicated by the north-seeking arrow on a lensatic compass.  Grid north is established by using the vertical grid lines on the map.

 There are two methods of measuring grid azimuths from one point to another on the map: 1. Protractor and string method. 2. Protractor and pencil method.  A grid azimuth CAN NOT be followed with a compass.

Step 1: Place the protractor on the map with the index mark at the center mass of the known point. Step 2: Ensure protractor’s vertical base line is parallel with the closest north-south grid line and horizontal base line is parallel with an east- west grid line.

Step 3: Make a mark on the map at the desired azimuth. Step 4: Draw a line connecting the known point and the mark on the map. Step 5: Use a piece of paper to transfer the distance from the scale to the plotted azimuth.

CPS Lesson Question (3-4)

True North can be found by finding what? A.Magnetic North B.Moss on a tree C.The North Star D.North on a map

Which of the following is NOT one of the two methods of measuring grid azimuths? A.Protractor and pencil method B.Protractor and ruler method C.Protractor and string method

 A back azimuth is the opposite of an azimuth.  It is the same as doing an “about face.”  Add 180° if the azimuth is 180° or less or subtract 180° if the azimuth is 180° or more.

 Because there is an angular difference between grid north and magnetic north, a conversion from magnetic to grid or vice versa is needed.  You cannot follow a grid azimuth with a compass, nor can you plot a magnetic azimuth with a protractor because of the angular difference between grid north and magnetic north.

CPS Lesson Question (5)

A back azimuth is the opposite of what? A.Azimuth B.North C.Circle D.South

Who might need to determine azimuths on a regular basis? (Use CPS “Pick a Student” for this question)

Images in this lesson were taken from:  Microsoft © Clip Art Gallery  Marine Corps Combat Camera