Telescopes & instruments · SNR = √N
Photon Shot-Noise SNR
The best signal-to-noise achievable when the only noise is the Poisson statistics of the photons themselves — the shot-noise limit. To double the signal-to-noise you must collect four times as many photons.
Signal-to-noise ratio100
Formula: SNR = √N
Worked example
With the default inputs, photon shot-noise snr evaluates to 100 — 10,000 photons → SNR 100. The validator recomputes this against the known value on every build, so the formula is checked, not asserted.
Highlights
- ›Quadruple photons to double SNR
The physics behind it
Knowledge connections
- Associated withLimiting Magnitude
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.