Speckle observations with PISCO in Merate (Italy): XIII. Astrometric measurements of visual binaries in 2012, and new orbits for ADS 10786 BC, 12144, 1215, 16314 and 16539

International audienceWe present relative astrometric measurements of visual binaries, made in 2012 with the speckle cameraPISCO at the 102-cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing listcontains orbital couples as well as binaries whose motion is still uncertain. We obtained 355 new measurementsof 344 visual binary stars, with angular separations in the range 0 ′′ .14 — 6 ′′ .9, and an average accuracy of0 ′′ .02. The mean error on the position angles is 0 ◦ .5. Most of the position angles were determined withoutthe usual 180 ◦ ambiguity with the application of triple-correlation techniques and/or by inspection of thelong integration files. We also present new revised orbits for ADS 10786 BC, 12144, 12515, 16314 and 16539,partly derived from PISCO observations. The corresponding estimated values for the masses of those systemsare compatible with the spectral types