Talk:Limiting magnitude
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For background limited observations, the limiting magnitude can be predicted from the derived zeropoints according to the formula (see McLean 1997):
mlim = zp-2.5log(S/N(nB/t)^1/2)
where: zp is the zeropoint magnitude (for 1 electron/sec), S/N is the requested signal-to-noise ratio, B is the background level (in electrons per second per pixel), t is the total on-source integration time and n is the number of pixels:
for point source: n = 3.1415 * (FWHM/pixel_size)^2 for extended source: n = (1/pixel_size)^2
