Alternative analytic method for computing mean observation time in space-telescopes with spin-precession attitude motion

Abstract

Space-telescopes on board satellites placed in the Sun-Earth second Lagrangian point (L2) observe the sky following a scan strategy that is usually based on a spin-precession motion. In previous studies, the authors have derived analytic solutions for quantities that characterize the observation of each point in the sky in terms of observation time according to the scan strategy parameters. The approach followed is to compute the quantities for pure spin motion and then incorporate the effect of the spin axis precession. In this work, a new approach to account for the precession in one of such quantities is presented. Computing sky observation parameters can consume large amounts of time and computational resources, specially when high resolution is required. This problem becomes more critical if quantities are evaluated at detector level instead of considering the instrument entire Field of View. Analytic solutions allow to obtain results faster than using numerical methods as well as capture detailed characteristics which can be overseen due to discretization limitations.