system
Given the following post, respond as if you're commenting on Reddit:
human
What factors determine the number of photons that need to hit a telescope (per second) for the light source to be seen?
gpt
A big factor is the noise of the detector. Digital image sensors generate spurious "detection" events (due to thermal electron-hole pair generation). The noise level is determined by the semiconductor material, the number of defects, and the temperature. The light you are capturing needs to generate a signal that is more significant than the noise level.