FOUR FIRST AND TWO RECALCULATED ORBITS FOR BINARIES

In this paper, we analyze new orbital elements, and quantities that can be derived from them, for six binaries. For four of them, WDS 00251+4803 = HDS 56, WDS 01071-0036 = HDS 144 AB, WDS 06426+3955 = HDS 930, and WDS 21014+4037 = HDS 2995, the orbital elements are calculated for the first time. For the other two, WDS 04195+3800 = HDS 552 and WDS 23209+1643 = HEI 88, the orbital elements are recalculated. Five binaries, denoted as HDS, were discovered during the Hipparcos mission while the remaining binary was discovered somewhat earlier. HEI 88 was measured for the first time in 1978. All studied pairs are close, with almost all measured separations less than 0.3 arcsec. For these binaries the observations were usually performed using the speckle-interferometric technique with the exception of HEI 88, which was observed visually on eight occasions. The resulting orbital periods fall within 13 and 69 years. In addition to the orbital elements, we also give (O-C) residuals in theta and rho, masses, dynamical parallaxes, absolute magnitudes, spectral types, and ephemerides for the next five years.