  The integrated Sachs-Wolfe (ISW) effect in a Lambda dominated universe can be
an important factor in the evolution of cosmic microwave background
fluctuations. With the inclusion of cosmological constant we present the
complete analytic solution of the covariant linear perturbations of the
Einstein equations in the Newtonian gauge, in the case of a spatially flat
(K=0), Friedman-Robertson-Walker (FRW) universe, filled with pressureless ideal
fluid. We use the analytic time dependence of the perturbation potentials to
derive the anisotropy power spectrum of the late ISW effect. We choose the
scale invariant Harrison-Zeldovich spectrum for obtaining the C_l momenta and
show the agreement of our results with earlier, numeric calculations.
