Observing basics
消光
Extinction
Atmosphere dimming starlight.
Roughly 0.2 magnitudes per air mass.
Related terms
- 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.
- Zenith — The point straight overhead, altitude 90°.