The effects of low temporal frequency modes on minimum variance maps from PLANCK

Abstract

We estimate the effects of low temporal frequency modes in the time stream on sky maps such as expected from the PLANCK experiment -- a satellite mission designed to image the sky in the microwave band. We perform the computations in a semi-analytic way based on a simple model of PLANCK observations, which permits an insight into the structure of noise correlations of PLANCK-like maps, without doing exact, computationally intensive numerical calculations. We show that, for a set of plausible scanning strategies, marginalization over temporal frequency modes with frequencies lower than the spin frequency of the satellite (= 1/60 Hz) causes a nearly negligible deterioration of a quality of the resulting sky maps. We point out that this observation implies that it should be possible to successfully remove effects of long-term time domain parasitic signals from the PLANCK maps during the data analysis stage.