The velocity-distance data for the nearest 15 galaxies are reexamined relative to the predicted deceleration curves for the idealized Local Group (LG) dynamical model of Sandage (1986). The dependence of the Kahn-Woltjer (1959) mass on the velocity of M31 and the Galaxy and on the age of the LG is discussed. Exact agreement between the present method and the previous one can be obtained if H(0) = 90 and Omega(0) = 0 and v(approach) = -90 km/s, giving a total LG mass of 3 x 10 to the 12th solar masses. However, the decleration method is sufficiently imprecise that a solution with H(0) = 55, Omega(0) = 0 is possible, giving a mass of a 1 x 10 to the 12th solar masses for the LG. It is concluded that the best mass for the LG may be the Kahn-Woltjer solution which, with t = 18 Gyr and the best-fit value of v(approach) = -115 km/s, gives an LG mass of 2.8 x 10 to the 12th solar masses.
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Allan Sandage (1987) studied this question.