Hipparcos trigonometric parallaxes and the distance scale for open star clusters

Hipparcos trigonometric parallaxes are used to estimate the distances to th e maximum possible number of open star clusters (OSC); distance moduli are estimated for 45 clusters with maximum heliocentric distances of about 1000 pc. The latter value can serve as an estimate of the limit to which it sti ll makes sense to use Hipparcos trigonometric parallaxes to determine the d istances to small groups composed of 6-10 sufficiently bright stars. A syst ematic correction to the distance moduli of clusters from the homogeneous c atalog of OSC parameters (Loktin et al. 1997, 2000) is estimated, which tur ns out to be independent of the cluster age. (C) 2001 MAIK "Nauka/Interperi odica".