Speckle observations with PISCO in Calern (France): I. Astrometric measurements of visual binaries in 2015–2016

We present relative astrometric measurements of visual binaries, made in 2015-2016 with the speckle camera PISCO at the 1-m Epsilon telescope of the C2PU facility (Observatoire de la Cote d'Azur, Calern site). Our observing list contains orbital couples as well as binaries whose motion is still uncertain. From our 1233 observations of 1173 multiple stars, we obtained 1170 new measurements with angular separations in the range 0 ′′ .1-8 ′′ .2, and an average accuracy of 0 ′′ .0078. The mean error on the position angles is 0 • .54. Most of the position angles were determined without the usual 180 • ambiguity with the application of the direct vector autocorrelation technique and/or by inspection of the long integration files.