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We present absolute trigonometric parallaxes and relative proper motions forthree members of the Pleiades star cluster, obtained with HST's Fine GuidanceSensor 1r, a white-light interferometer. We estimate spectral types andluminosity classes of the stars comprising the astrometric reference frame fromR \approx 2,000 spectra, VJHK photometry, and reduced proper motions. Fromthese we derive estimates of absolute parallaxes and introduce them into ourmodel as observations with error. We constrain the three cluster members tohave a 1 sigma dispersion in distance less than 6.4 pc, and find an averagepi_{abs}=7.43+-0.17+-0.20 milliseconds of arc, where the second error issystematic due to member placement within the cluster. This parallaxcorresponds to a distance of 134.6+-3.1 pc or a distance modulus of(m-M)=5.65+-0.05 for these three Pleiads, presuming a central location. Thisresult agrees with three other independent determinations of the Pleiadesdistance. Presuming that the cluster depth systematic error can besignificantly reduced because of the random placement of these many memberswithin the cluster, these four independent measures yield a best-estimatePleiades distance of pi_{abs}=7.49+-0.07 milliseconds of arc, corresponding toa distance of 133.5+-1.2 pc or a distance modulus of (m-M)=5.63+-0.02. Thisresolves the dispute between the main sequence fitting and the Hipparcosdistance moduli in favor of main sequence fitting.Comment: 9 pages, 10 tables, 6 figures; AJ in press (March 2005 issue

Confirmation of Errors inHipparcosParallaxes fromHubble Space TelescopeFine Guidance Sensor Astrometry of the Pleiades