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

Abstract

International audienceWe 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\farcs1-4\arcsec, and with an average accuracy of 0\farcs01. 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\fdg8. We have found a possible new triple system: ADS 11077. ?kip0.15cm 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

Preliminary orbital elements of six visual binary stars

“…Since the installation of PISCO on the 102-cm Zeiss telescope in 2004, this raises to fourteen the total number of the published orbits, that we have computed with measurements obtained in Merate (Scardia et al 2005(Scardia et al , 2006(Scardia et al , 2007a(Scardia et al ,b, 2008.…”

“…Since 2004 it has been mounted and operated at the Cassegrain focus of the INAF-OAB, 102-cm Zeiss telescope in Merate. Details about the data reduction procedure and the PISCO measurements used for this work can be found in Scardia et al (2005Scardia et al ( , 2007a. The purpose of our long-term program is to provide good-quality measurements of close visual binaries in order to improve the quality of the orbits and derive estimates of the stellar masses.…”

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

“…It is the fourteenth of a series whose purpose is to contribute to the determination of binary orbits (Scardia et al 2005(Scardia et al , 2006(Scardia et al , 2007(Scardia et al , 2008aPrieur et al 2008;Scardia et al 2009;Prieur et al 2009;Scardia et al 2010;Prieur et al 2010;Scardia et al 2011;Prieur et al 2012;Scardia et al 2013;Prieur et al 2014, herein Papers I to XIII). The focal instrument PISCO was developed at Observatoire Midi-Pyrénées (France) and first used at Pic du Midi from 1993 to 1998.…”

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

“…It is the tenth of a series (Scardia et al 2005(Scardia et al , 2006(Scardia et al , 2007(Scardia et al , 2008aPrieur et al 2008;Scardia et al 2009;Prieur et al 2009;Scardia et al 2010;Prieur et al 2010, herein: Papers I to IX), whose purpose is to contribute to the determination of binary orbits. PISCO was developed at Observatoire Midi-Pyrénées (France) and first used at Pic du Midi from 1993 to 1998.…”