Altitude is the height of the star, in degrees above the horizon. The drawback to this system is that as a star rises and sets, it's position in the sky relative to the due north and its height change. This means that the azimuth and altitude change throughout the night and that observers at two different locations could see the same star at different azimuth altitude coordinates. Right Ascension and Declination Right ascension and declination are similar to longitude and latitude. The lines similar to the longitude lines on a globe are called Right Ascension.
Right ascension is measured around the celestial equator towards the east.
This angle is measured in hours, minutes, and seconds. An object with a right ascension of 0 hours lies on the Vernal Equinoctal. Declination is similar to latitude and measures how far above or below the celestial equator an object is. Since the Right Ascension and Declination are relative to fixed stars, these coordinates do not change over time or with the position of the observer.