Speckle observations with PISCO in Merate (Italy): XIV. Astrometric measurements of visual binaries in 2013, and new orbits for ADS 1097, 5871, 7203, 7775, 9378, 9578 and 11186
Résumé
We present relative astrometric measurements of visual binaries, made in 2013 with the speckle camera PISCO at the 102-cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 134 new measurements of 129 visual binary stars, with angular separations in the range 0 ′′ .23-5 ′′ , and an average accuracy of 0 ′′ .01. The mean error on the position angles is 0 • .5. Most of the position angles were determined without the usual 180 • ambiguity with the application of triple-correlation techniques and/or by inspection of the long integration files. We also present new revised orbits for ADS 1097, 5871, 7203, 7775, 9378, 9578 and 11186, partly derived from PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types.
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