Following the treatment of Hoyng(1989), the photometer measures the flux of a star every seconds, during an entire stretch of T seconds, hence we have contiguous, independent (with respect to the noise) measurements. The photon noise in the power spectrum of the data in units of Hz-1 is given by
| (1) |
where F is the detected electron rate generated in the detector by the light of the star. For , decreases rapidly to zero. The photometric precision due to photon statistics in one single measurement of seconds is found by integrating (3.1) over all frequencies:
| (2) |
The total photometric precision due to photon statistics in T seconds by adding independent measurements of seconds is equal to
| (3) |
is the total number of electrons collected during the entire observation of T seconds. Note that is also equal to the integrated photon noise power in the smallest frequency bin , since .