Resumen
We present the general guidelines and first results of an astrometric project for the characterization, in terms of proper motions, of the low-mass star and substellar populations in 180 square degrees of the Orion star forming region. The first results of the astrometric reductions show coordinate uncertainties of ~ 0.004'' which, with the 10 year span of our observations, will allow for the detection of proper motions down to ~ 0.001''/year.
