We propose a photometric technique for future space missions that overcomes
the problem of Nyquist aliases. These aliases result from typically long
cadences of observation imposed by telemetry constraints. The proposed method
is to introduce a periodic modulation to the sampling rate. Suitable
combinations of the frequency and the amplitude of this modulation allow the
true peaks to be distinguished from the aliases. We provide an analytical proof
of the validity of this method and some demonstrations with simulated data. We
also propose to divide a long cadence into two unequal parts, aiming at
reproducing the intrinsic amplitude spectrum of stars without a severe smearing
effect due to long exposures. The two exposures can be summed to recover the
photon statistics if the user is interested in doing so. Based on these
proposals, a specific recommendation for the PLATO mission is made to maximise
its capability of photometry for asteroseismology, without serious interference
with its other scientific missions.Comment: 13 pages, fig11a was replaced with the correct one. Proceedings of
the PHOST "Physics of Oscillating Stars" conference (2-7 Sept. 2018,
Banyuls-sur-mer, France), Edited by J. Ballot, S. Vauclair, & G. Vauclai
