We present results on parallaxes , magnitudes and proper motions for 17 optically identified massive X-ray binaries ( MXRB ) which were observed during the Hipparcos astrometry mission .
This sample includes the sources detected in the medium-energy range ( 2-10 keV ) having optical counterparts brighter than V =12 .
We compare the Hipparcos results with ground-based optical data and derive probable values for absolute magnitudes and peculiar tangential velocities ( v _ { \mathrm { t } } ) .
The 4 OB supergiant systems in our sample are high-velocity objects ( the average value of v _ { \mathrm { t } } is greater than 60 km/s ) , while the 13 Be systems have low velocities ( < v _ { \mathrm { t } } > = 11.3 \pm 6.7 km/s ) , suggesting a different formation mechanism for the two subgroups .
The unusual X-ray/radio source LSI+61 ^ { \circ } 303 lies much closer than previously believed and its low optical luminosity ( M _ { \mathrm { V } } = +2.2 ) and blue intrinsic colors now suggest it may be a peculiar type of low-mass X-ray binary .