2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/143614The most recent cosmological observations indicate that the present universe is flat and vacuum dominated. In such a universe, the distance measurements are always difficult and involve numerical computations. In this paper, it is shown that the most fundamental distance measurement of cosmology, the luminosity distance, for such a universe can be obtained in an approximate analytical way with very small errors of less than 0.02% up to %z = 5$ for any value of vacuum energy. The analytical calculation is shown to be exceedingly efficient, as compared to the traditional numerical methods.Astrophysicstext