Telescopes & instruments · m_lim ≈ 2.7 + 5 log₁₀(D_mm)
Limiting Magnitude
A rule-of-thumb estimate of the faintest star an aperture can show under dark skies. Approximate — real limits depend on sky brightness, magnification, and the observer — so it is offered as a guide, not a guarantee.
Limiting magnitude12.7mag
Formula: m_lim ≈ 2.7 + 5 log₁₀(D_mm)
Worked example
With the default inputs, limiting magnitude evaluates to 12.7 mag — 100 mm → ~12.7 mag. The validator recomputes this against the known value on every build, so the formula is checked, not asserted.
Highlights
- ›100 mm: ~12.7 mag (approx.)
The physics behind it
Knowledge connections
- Associated withAngular Resolution (Rayleigh)
- Associated withPhoton Shot-Noise SNR
Sources
The primary and reference sources this topic draws on.
- NASANational Aeronautics and Space Administration
Mission data, planetary science, space telescopes, and public-domain imagery.
Most NASA-produced imagery is in the public domain; individual items are checked for usage terms before publication.