A preliminary visual orbit of BY Draconis

We report on the preliminary determination of the visual orbit of the double-lined spectroscopic binary system BY Draconis with data obtained by the Palomar Testbed Interferometer in 1999. BY Dra is a nearly equal-mass double-lined binary system whose spectroscopic orbit is well known. We have estimated the visual orbit of BY Dra from our interferometric visibility data fit both separately and in conjunction with archival radial velocity data. Our BY Dra orbit is in good agreement with the spectroscopic results. Due to the orbit's face-on orientation, the physical parameters implied by a combined fit to our visibility data and radial velocity data do not yet result in precise component masses and a system distance, but with continued interferometric monitoring we hope to improve the mass estimates to better than 10% determinations.