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Keywords:

  • techniques: high angular resolution;
  • astrometry;
  • binaries: general;
  • binaries: visual

ABSTRACT

We present relative positions of visual binaries observed in 2009 with the FastCam ‘lucky-imaging’ camera mounted on the 1.5-m Carlos Sánchez Telescope at the Observatorio del Teide. We obtained 424 CCD observations (averaged in 198 mean relative positions) of 157 binaries with angular separations in the range 0.14–15.40 arcsec, with a median separation of 0.51 arcsec. For a given system, each CCD image represents the sum of the best 10–25 per cent images from 1000–5000 short-exposure frames. Derived internal errors were 7 mas in ρ and 1bsl000642 (9 mas) in θ. When comparing to systems with very well known orbits, we find that the rms deviation in ρ residuals is 23 mas, while the rms deviation in θ residuals is 0bsl0006473/ρ. We confirmed 18 Hipparcos binaries and we report new companions to BVD 36 A and J 621 B. For binaries with preliminary orbital parameters, the relative radial velocity was estimated as well. We also present four new revised orbits computed for LDS 873, BU 627 A-BC, BU 628 and HO 197 AB. This work discusses the first results on visual binaries using the FastCam lucky-imaging camera.