Observing basics
极限星等
Limiting magnitude
The faintest magnitude visible under current conditions.
About 4 in a city, up to 6.5 under a dark sky.
Related terms
- Air mass — Relative air path; 1 at zenith.
- Extinction — Atmosphere dimming starlight.
- Dark adaptation — Eyes adjusting to darkness over 20–40 minutes.
- Averted vision — Looking slightly off-target to use rod-rich retina.