Observing basics
大气质量
Air mass
Relative air path; 1 at zenith.
At 30° altitude it is about 2 air masses.
Related terms
- Apparent magnitude — Brightness as seen from Earth, not intrinsic output.
- Absolute magnitude — The magnitude an object would have at 10 parsecs.
- Altitude — Angle above the horizon: 0° at the horizon, 90° at zenith.
- Azimuth — Horizontal angle measured clockwise from north.