Speckle Observations of Binary Stars with the Wiyn Telescope. I. Measures during 19971

Two hundred seventy-seven position angle and separation measures of 154 double stars are presented. Three of the systems were previously unknown to be double, and 16 other systems were discovered earlier this decade by the Hipparcos satellite. Measures are derived from speckle observations taken with the Wisconsin-Indiana-Yale-NOAO (WIYN) 3.5 m telescope located at Kitt Peak, Arizona. Speckle images were obtained using two di†erent imaging detectors, namely, a multianode microchannel array (MAMA) detector and a fast-readout CCD. A measurement precision study was performed on a sample of binaries with extremely well known orbits by comparing the measures obtained here to the ephemeris predictions. For the CCD, the root mean square (rms) deviation of residuals was found to be 3.5 milliarcseconds (mas) in separation and in position angle, while the residuals of the MAMA data varied 1¡.2 depending on the magniÐcation used and seeing conditions but can be comparable or superior to the CCD values. In addition, the two cameras were compared in terms of the detection limit in total magnitude and magnitude di†erence of the systems under study. The MAMA system has the ability to detect some systems with magnitude di†erences larger than 3.5, although reliable astrometry could not be obtained on these objects. Reliable astrometry was obtained on a system of magnitude di†erence of 5.3 with the CCD system.