CCD SPECKLE OBSERVATIONS OF BINARY STARS FROM THE SOUTHERN HEMISPHERE. IV. MEASURES DURING 2001

We present 549 observations of 181 primarily southern binary stars. Of these, 32 are high-quality nondetections, meaning that, if binary, the system had a separation below the diffraction limit at the time of the observation, and relative astrometry is presented for the remaining 517 observations. In addition, a magnitude difference measure is reported in 312 cases in which the observation was judged to be of sufficient quality to have little decorrelation of the speckle pattern of the secondary relative to the primary star. These data were obtained from speckle observations taken at the LowellTololo 0.6 m telescope at Cerro Tololo Inter-American Observatory using a fast-readout CCD detector during 2001 November. Results from an astrometric measurement precision study indicate that the measures have typical uncertainties of 12.2(plus-minus)1.4 mas in separation and 1°.28(plus-minus)0°.21 in position angle with little systematic error. The magnitude differences presented show good agreement with values in the Hipparcos catalog where comparisons can be made. Their uncertainties are also characterized; they show a typical value of 0.18 mag per 2 minute observation. Four systems of particular interest are discussed.