Speckle Observations With PISCO in Calern (France): III . Astrometric Measurements of Visual Double Stars in 2019 and New or Revised Orbits for

ABSTRACT

We present relative astrometric measurements of visual double stars, made in 2019 with the speckle camera PISCO at the 1‐m Epsilon telescope of the C2PU facility (Observatoire de la Côte d'Azur, Calern site). Our observing list contains orbital couples as well as double stars whose motion is still uncertain. From our observations of 698 multiple stars, we obtained 679 new measurements with angular separations in the range 0″.1–7″.5, and an average accuracy of 0″.007. 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 the direct vector method, the restricted correlation technique, and/or by inspection of the long integration files. We present new and revised orbits for STT531 AB, STT77 AB, STF1338 AB, COU1746, STT260, A1109 AB, HU1291, and A632 AB, partly derived from our PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types.