# How to Calculate Azimuth

Yes, it's spherical trigonometry – but it's not rocket science! Azimuth is simply the angle of an object in the sky along the horizon.

### Instructions

• Step 1: Determine latitude and longitude Determine the latitude and longitude of the starting point, or observation point, from which you'll calculate the angle. Use L to represent the starting point latitude.
• TIP: Find latitude and longitude by going to the location with a GPS device.
• Step 2: Find object's coordinates Find the latitude and longitude of the celestial object. Use D to represent the latitude of the point on the earth where the desired object is straight overhead.
• Step 3: Find t Find the meridian angle, represented by t, also known as the local hour angle – or LHA. It is the difference between the observer's longitude and the longitude of the celestial object.
• Step 4: Calculate the altitude Calculate the altitude of the object, called H. Multiply the sine of L by the sine of D. Then multiply the cosine of L by the cosine of D, by the cosine of t. Add these two products and determine the arcsine of the sum.
• Step 5: Compute azimuth Find the azimuth angle, Z, by multiplying the cosine of D by the sine of t, and dividing the product by the cosine of H. Then determine the arcsine of the result, which will give you the azimuth angle.
• FACT: The distance between Earth and our moon is, on average, 238,900 miles.

### You Will Need

• The latitude and longitude of starting point
• The latitude and longitude of the celestial object
• A calculator with sine
• cosine
• and arcsine functions
• A chart or map (optional)
• A GPS device (optional)