Speckle observations with PISCO in Merate – II. Astrometric measurements of visual binaries in 2004

We present relative astrometric measurements of visual binaries taken during the second semester of 2004 with the Pupil Interferometry Speckle camera and Coronagraph (PISCO) at the 1-m Zeiss telescope of the Brera Astronomical Observatory, in Merate, Italy. We performed 207 new observations of 194 objects with angular separations in the range 0.1–4.0 arcsec and an accuracy better than ∼0.01 arcsec. Our sample contains orbital couples as well as binaries whose motion is still uncertain. Our purpose is to improve the accuracy of the orbits and constrain the masses of the components.
Those measurements show that the orbit of ADS 15115 needs to be revised; we propose a new orbit for this object.     

Speckle observations with PISCO in Merate – V. Astrometric measurements of visual binaries in 2006

We present relative astrometric measurements of visual binaries made during the first semester of 2006, with the Pupil Interferometry Speckle camera and COronagraph at the 102-cm Zeiss telescope of the Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 217 new measurements of 194 objects, with angular separations in the range 0.1–4.2 arcsec, and an average accuracy of 0.01 arcsec. The mean error on the position angles is 05. About half of those angles could be determined without the usual 180° ambiguity by the application of triple-correlation techniques. We also present a revised orbit for ADS 277 for which the previously published orbit resulted in a large residual from our measurements.     

Speckle observations with PISCO in Merate: VI. Astrometric measurements of visual binaries in 2006

We present relative astrometric measurements of visual binaries made during the second semester of 2006, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 175 new measurements of 169 objects, with angular separations in the range 0″.1–4″.2, and an average accuracy of 0″.01. The mean error on the position angles is 0°.6. Most of the position angles could be determined without the usual 180° ambiguity with the application of triplecorrelation techniques and/or by inspection of the long integration files.We also present the new orbits we have computed for ADS 11479, 11584 and 16538, for which our measurements lead to large residuals and/or for which the revision was justified by the significant number of observations made since the last orbit computation (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate – VII. Astrometric measurements of visual binaries in 2007

We present relative astrometric measurements of visual binaries made during the first semester of 2007, with the Pupil Interferometry Speckle camera and COronagraph (PISCO) at the 102-cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 226 new measurements of 214 objects, with angular separations in the range 0.15–4.5 arcsec, and an average accuracy of 0.013 arcsec. The mean error on the position angles is     . Most of the position angles could be determined without the usual 180° ambiguity with the application of triple-correlation techniques and/or by inspection of the long integration files. We also present the new orbits we have computed for ADS 7871, 7982 and 8128, for which our measurements lead to large residuals and/or for which the revision is justified by the significant number of observations made since the publication of the previous orbit.     

Speckle observations with PISCO in Merate: IV. Astrometric measurements of visual binaries in 2005

We present relative astrometric measurements of visual binaries made during the second semester of 2005, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. The purpose of this long term program is to improve the accuracy of the orbits and determine the masses of the components. We performed 130 new observations of 120 objects, with most of the angular separations in the range 0″.1–4″, and with an average accuracy of 0″.01. Most of the position angles could be determined without the usual 180. ambiguity with the application of triple‐correlation techniques, and their mean error is 0°8. We have found a possible new triple system: ADS 11077. The measurements of the closest binaries were made with a new data reduction procedure, based on model fitting of the background of the auto‐correlations. As this procedure proved to be very efficient, we have re‐processed the old observations of close binaries made with PISCO in Merate since 2004. We thus improved 20 measurements already published and obtained 7 new measurements for observations that were previously reported as “unresolved”. We finally present revised orbits for ADS 684, MCA 55Aac (in the Beta 1 Cyg–Albireo multiple system) and ADS 14783 for which the previously published orbits led to large residuals with our measurements and for which the new observations made since their computation allowed a significant improvement of those old orbits. The sum of the masses that we derived for those systems are consistent with the spectral type of the stars and the dynamic parallaxes are in good agreement with the parallaxes measured by Hipparcos. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: X. Astrometric measurements of visual binaries in 2009

We present relative astrometric measurements of visual binaries, made in 2009 with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 345 new measurements of 259 objects, with angular separations in the range 0.″18–4.″6, and an average accuracy of 0.″011. The mean error on the position angles is 0.°6. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We have found a possible new close component for ADS 2377, which would be a new quadruple star system. We also present new revised orbits for ADS 8035, 9982, 11484, and MLR 198, partly derived from those observations, and infer estimated values for the masses of those systems that are compatible with the spectral types (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: VIII. Astrometric measurements of visual binaries in 2007 and new orbits of the multiple system Zeta Aqr

We present relative astrometric measurements of visual binaries made during the second semester of 2007, with the speckle camera PISCO at the 102 cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our sample contains orbital couples as well as binaries whose motion is still uncertain. We obtained 283 new measurements of 279 objects, with angular separations in the range 0″.17–4″.4, and an average accuracy of 0″.014. The mean error on the position angles is 0°.6. Most of the position angles were determined without the usual 180° ambiguity with the application of triple‐correlation techniques and/or by inspection of the long integration files. We also present the new orbit we have computed for Zeta Aqr AB (ADS 15971), for which our measurements lead to large residuals with the previously computed orbit. We were also able to compute the elements of the perturbation orbit Bb‐P caused by an invisible companion, whose mass is estimated at 0.7 M_⊙ (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate: XIII. Astrometric measurements of visual binaries in 2012, and new orbits for ADS 10786 BC, 12144, 12515, 16314 and 16539

We present relative astrometric measurements of visual binaries, made in 2012 with the speckle camera PISCO at the 102‐cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 355 new measurements of 344 visual binary stars, with angular separations in the range 0′.14–6′.9, and an average accuracy of 0.′02. 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 triple‐correlation techniques and/or by inspection of the long 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 systems are compatible with the spectral types. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Speckle observations with PISCO in Merate (Italy): XIV. Astrometric measurements of visual binaries in 2013 and new orbits for ADS 1097, 5871, 7203, 7775, 9378, 9578, and 11186

We present relative astrometric measurements of visual binaries made in 2013 with the speckle camera PISCO at the 102‐cm Zeiss telescope of Brera Astronomical Observatory, in Merate. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. We obtained 134 new measurements of 129 visual binary stars, with angular separations in the range 0.≈23–5 and an average accuracy of 0.≈01. 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 triple‐correlation techniques and/or by inspection of the long integration files. We also present new revised orbits for ADS 1097, 5871, 7203, 7775, 9378, 9578, and 11186, partly derived from PISCO observations. The corresponding estimated values for the masses of those systems are compatible with the spectral types. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Relative astrometric and photometric measurements of visual binaries made with the Nice 76‐cm refractor in 2008

We present relative astrometric and photometric measurements of visual binaries made in 2008, with the 76‐cm refractor of Côte d'Azur Observatory. Our observing list contains orbital couples as well as binaries whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky imaging, speckle interferometry and the Direct Vector Autocorrelation method. We obtained 2420 new measurements of the relative position of 2225 objects, with angular separations in the range 0″.07‐11″.5, and an average accuracy of 0″.02. The mean error on the position angles is 0°.6. We managed to observe faint systems (m_V ≈ 12) with large magnitude difference (up to Δm_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 difference of magnitude of the two components of 376 objects with an estimated error of 0.1 mag. Finally, we provide a list of 33 newly discovered components of multiple or binary systems, which is a significant complement to our GII catalog (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Relative astrometry and near‐infrared differential photometry of nearby southern orbital binaries with adaptive optics

We present relative astrometry and differential photometry measurements for a sample of nearby southern orbital binaries making use of the technique of Adaptive Optics. The observations were made in December 2000, with the ADONIS camera mounted at the 3.6‐m ESO telescope from La Silla Observatory, equipped with the broad‐band near‐infrared filters (J ‐, H ‐, K ‐passbands). Our sample contains stars which do not fit very well the empirical mean mass‐luminosity relation (according to our previous study), but for which accurate parallaxes (determined by the Hipparcos satellite) and high‐quality orbits were available thanks to many previous efforts. We derived accurate positions and J, H, K magnitudes of the individual components of those binaries. The individual stellar components have near‐infrared colour indices well grouped in those plots and are comparable to standard single stars. The data reduction procedure used for deriving those results is described in detail. It is based on a least‐squares fit of Moffat‐Lorentz profiles in direct imaging for well‐resolved systems and on Fourier analysis for very close pairs. (© 2013 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)