  A number of experiments for measuring anisotropies of the Cosmic Microwave
Background use scanning strategies in which temperature fluctuations are
measured along circular scans on the sky. It is possible, from a large number
of such intersecting circular scans, to build two-dimensional sky maps for
subsequent analysis. However, since instrumental effects --- especially the
excess low-frequency 1/f noise --- project onto such two-dimensional maps in a
non-trivial way, we discuss the analysis approach which focuses on information
contained in the individual circular scans. This natural way of looking at CMB
data from experiments scanning on the circles combines the advantages of
elegant simplicity of Fourier series for the computation of statistics useful
for constraining cosmological scenarios,and superior efficiency in analysing
and quantifying most of the crucial instrumental effects.
