Azimuth is the angle, typically using true north as zero degrees to an object from viewers location. An altitude (if expressed as an elevation angle from the viewer) provides a line of sight to an object in space. If you were standing at a point and facing true north and there was an airplane flying at 20,000 ft and you knew the elevation angle you could compute the range and have an (X,Y,Z) location for the object.
location of a star
The azimuthal grid is a coordinate system that stays still while the stars move across it on the sky (the celestial sphere). It measures the altitude above the horizon and the azimuth (position along the horizon) of the celestial object at a particular time, for a particular place.
The azimuthal grid is a coordinate system that stays still while the stars move across it on the sky (the celestial sphere). It measures the altitude above the horizon and the azimuth (position along the horizon) of the celestial object at a particular time, for a particular place.
You have to convert them to Polar Points or the Azimuth points and use the angle difference.
North
fu
There are a number of ways to describe locations or positions. One of these is to describe the direction toward an object in degrees; this is the "azimuth". For objects in the sky, we must also know the angular elevation above the horizon, or "altitude angle". This is usually shortened to "altitude". By specifying the azimuth angle and altitude angle, we can describe precisely the direction of any object in the sky.
The azimuth and altitude of Sagittarius depend where you are on Earth and the date and time. The altitude can be anything form 0-90, and the azimuth 0-180.
azimuth 100 degrees altitude 20 degrees
Azimuth = 315° (True) Altitude = 0
The variation of the apparent azimuth and altitude of everything we see in the sky is the result of Earth's rotation.
The variation of the apparent azimuth and altitude of everything we see in the sky is the result of Earth's rotation.
The point on the horizon that is due west has an altitude of zero and an azimuth of 270 degrees.
An object seen halfway between the horizon and the zenith has an altitude of 45 degrees.An object seen due east of the observer has an azimuth of 90 degrees.
Azimuth is the angle, typically using true north as zero degrees to an object from viewers location. An altitude (if expressed as an elevation angle from the viewer) provides a line of sight to an object in space. If you were standing at a point and facing true north and there was an airplane flying at 20,000 ft and you knew the elevation angle you could compute the range and have an (X,Y,Z) location for the object.
http://samos.martech.fsu.edu/courses/spring08/telescopeoperation.htm
The two types of sundials are altitude and azimuth sundials.
This is probably about the "horizon coordinate system". Or, it's sometimes called the horizontal coordinate system. The system uses "altitude" and "azimuth" as coordinates. The azimuth is normally measured from due North as zero. So, that's the "three reference points", probably. Altitude is the angular height of a star above the horizon. Azimuth is the angle of a star measured along the horizon, from the pole.