Measurements of visual binaries with PISCO2 at the Nice 76-cm refractor in 2011-2012
Résumé
We present relative astrometric and photometric measurements of visual binaries made in 2011-2012, with
PISCO2 installed at the 76-cm refractor of Côte d’Azur Observatory in Nice (France). Our observing list
contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques have
been used for obtaining those measurements: Lucky Imaging, Speckle Interferometry and the Direct Vector
Autocorrelation method. From our observations of 3136 multiple stars, we obtained 3568 new measurements
with angular separations in the range 0 ′′ .1 — 10 ′′ and an average accuracy of 0 ′′ .016. The mean error on the
position angles is 1 ◦ .7. 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 Lucky images or the
long integration files. We managed to routinely monitor faint systems (m V ≈ 9 − 11) with large magnitude
difference (up to ∆m V ≈ 5). We have thus been able to measure many systems containing red dwarf stars
that had been poorly monitored since their discovery. We also measured the magnitude difference of the two
components of 326 binaries with an estimated error of 0.2 mag. Except for a few objects that have been
discussed, our measurements are in a good agreement with the ephemerides computed with published orbital
elements, even for the binaries closer than the diffraction limit. Thanks to good seeing images and with the
use of high-contrast numerical filters, we have also been able to obtain 196 measurements with an angular
separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with
larger telescopes. We also obtained new measurements of the 15th magnitude multiple system CON37, and
discovered a faint new double star in its vicinity. Finally, we report 47 measurements of 28 new binaries found
during our observations.
Origine : Fichiers produits par l'(les) auteur(s)