Speckle observations with PISCO in Merate (Italy): XV. Astrometric measurements of visual binaries in 2014, and new orbits for ADS 671, 1615, 1709, 5447, 10075 and 12447.

International audienceWe present relative astrometric measurements of visual binaries, made in 2014 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 224 new measurements of 218 visual binary stars, with angular separations in the range 0 ′′ .15-10 ′′ , and an average accuracy of 0 ′′ .015. 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 complete this data with the results of a study of the multiple system ADS 6993 with PISCO during the period 2004-2014 and propose a new method to resolve part of the 180-degree ambiguity with the autocorrelations only. We then present new revised orbits for ADS 671, 1615, 1709, 5447, 10075 and 12447, partly derived from PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types