It has been shown recently that relativistic distortions generate a dipolar modulation in the two-point correlation function of galaxies .
To measure this relativistic dipole it is necessary to cross-correlate different populations of galaxies with for example different luminosities or colours .
In this paper , we construct an optimal estimator to measure the dipole with multiple populations .
We show that this estimator increases the signal-to-noise of the dipole by up to 35 percent .
Using 6 populations of galaxies , in a survey with halos and number densities similar to those of the millennium simulation , we forecast a cumulative signal-to-noise of 4.4 .
For the main galaxy sample of SDSS at low redshift z \leq 0.2 our optimal estimator predicts a cumulative signal-to-noise of 2.4 .
Finally we forecast a cumulative signal-to-noise of 7.4 in the upcoming DESI survey .
These forecasts indicate that with the appropriate choice of estimator the relativistic dipole should be detectable in current and future surveys .