 In fact, almost no stars with spectral type later than F appear among his objects.On the other hand, his results were not fully conclusive because there are known regions in the sky with many stars of the same spectral type but in which it is difficult to find two stars with the same proper motions or radial velocity.A striking example of this fact is Upgren 1; initially, it was suggested that this small group of seven F stars was the remnant of an old cluster (Upgren & Rubin 1965) but later, Gatewood et al.