Читать книгу The Doppler Method for the Detection of Exoplanets - Professor Artie Hatzes - Страница 31

The gain can also be calculated from just a couple of flat and dark frames:

 Two frames are taken, f1 and f2, at reasonably high intensity levels (∼10,000) as well as two bias frames, b1 and b2 (zero exposure times).

 Difference frames are produced from the bias and flats: b12=b1−b2 and f12=f1−f2. The use of differences removes any underlying structure that may be present.

 One then calculates the mean values of the bias frames, mb1 and mb2, the flat frames, mf1 and mf2, as well as the standard deviations of the difference frames, σf12 and σb12.

 The gain is given byG=mf1+mf2−mb1−mb2σf122−σb122.(2.21)