•Assume
you want to take N minutes total exposure time
•How
many exposures should you take to get N minutes total integration time?
–One long exposure might be good except
for saturation and blooming or excessive dark current and maybe
aircraft/spacecraft trails or poor tracking
–More exposures that are short may
degrade the s/n due to cumulative read noise effects
•Dark
shot noise, dark fixed pattern noise, Light fixed pattern noise and sky
background are all ignored
–Dark shot and Dark fixed pattern noise
addressed via cooling
–Light fixed pattern noise addressed by
flat-fielding
–Background is suppressed by imaging in
dark skies with emission line filters
•All
that is considered is Signal Shot noise and Read Noise
•Noise
= SQRT ( signal + read_noise^2)
•S/N
= signal / noise
