New Results for Three Nearby OB Associations

Abstract: We have developed a new procedure to identify moving groups, and have applied it to carry out a census of the nearby OB associations based on Hipparcos parallaxes and proper motions (see de Bruijne et al. and de Zeeuw et al. elsewhere in this volume). Here we present three illustrative cases. For list, while for Collinder 121 the Hipparcos data change the whole appearance of the association. Finally, we report the discovery of a new association in the field of Cepheus OB2.