  It is shown that by fitting a Markovian quantum master equation to the
numerical solution of the time-dependent Schr\"odinger equation of a system of
two spin-1/2 particles interacting with a bath of up to 34 spin-1/2 particles,
the former can describe the dynamics of the two-spin system rather well. The
fitting procedure that yields this Markovian quantum master equation accounts
for all non-Markovian effects in as much the general structure of this equation
allows and yields a description that is incompatible with the Lindblad
equation.
