Find the observer’s location and the exact date and time
Locate the altitude scale, which measures how high an object is above the horizon
Locate the azimuth scale, which measures direction along the horizon from north
Read altitude as the angle upward from the horizon to the object
Read azimuth as the compass direction of the object, usually in degrees from 0° to 360°
Use north as 0° or 360°, east as 90°, south as 180°, and west as 270° unless the chart states otherwise
Match the object’s position on the chart to both its altitude and azimuth values
Check whether the chart uses true north or magnetic north
Confirm whether altitude is measured in degrees above the horizon or in another unit
Confirm whether azimuth is measured clockwise from north or from another reference point
If the chart is a sky map, align it with the correct date, time, and direction you are facing
If the chart is a polar or circular chart, read azimuth around the outer edge and altitude from the center outward or inward as labeled
Use the chart legend or labels to verify the scale and orientation
Compare the object’s plotted position with the nearest grid lines to estimate values accurately