sample as it is the most complete and it is distributed more or less uniformly across the complex. RA,DEC positions were fed into the code as a sample of bivariate observations. We chose to use circular Gaussians to minimize the number of parameters required for the estimation. Given the complicated layout of the clusters in W3, we opted to run the GMM analysis including noise modeling and rejection of outliers[^8]. For our dataset, a model of five clusters provided the best fit for the sample. This is shown in Figure \[fig:GMM\]. While this finite mixture model shows less detail than –for instance– the nearest neighbor analysis, we see that it succeeds at identifying the three well known clusters in the region (W3-Main, W3(OH), IC 1795). It also adds two more principal clusters, one coinciding with NGC 896, the compact HII region located at the Western edge of the complex, and one more located at the Eastern edge. We labelled this group IC 1795-N. In Table \[tab:principal\_clusters\] we list the result of the GMM analysis, with the centers and radii of the five principal clusters identified (columns 1 to 4).

We emphasize that the purpose of this exercise is to define 