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Coordinate system · alt, az

The Horizontal Coordinate System

The observer-centred system that describes where a body appears in the local sky: altitude above the horizon and azimuth around it. Simple and intuitive for pointing a telescope, horizontal coordinates change continuously as the Earth turns and depend on the observer's location and the moment of observation.

Highlights

  • Altitude and azimuth in the observer's local sky

Across the reference systems

Knowledge connections

Sources

The primary and reference sources this topic draws on.

  • IAUInternational Astronomical Union

    Official naming, definitions, constellation boundaries, and astronomical nomenclature.