Speckle observations with PISCO in Calern (France): I. Astrometric measurements of visual binaries in 2015–2016

Scardia, M.; Rivet, J. P.; Prieur, Jean‐Louis; Pansecchi, Luigi; Argyle, R. W.; Ling, J. F.; Aristidi, Éric; Zanutta, Alessio; Vernet, David; Abe, Lyu; Bendjoya, Philippe; Dimur, Cécile; Suárez, Olga

doi:10.1002/asna.201913642

Cited by 8 publications

(6 citation statements)

References 26 publications

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“…Most of the high angular resolution observations presented here have been obtained with the “speckle interferometry” technique that was derived from the pioneering work of Labeyrie (1970). More precisely, we have used the method described in Worden et al (1977) which works with a “flattened” autocorrelation and is routinely used for PISCO (see Scardia et al 2019, for instance). The whole processing was done in two steps: real‐time processing with the BuildSpeck1 program and post‐processing with programs like Gdpisco (see Paper III for more details).…”

Section: Data Reduction Proceduresmentioning

confidence: 99%

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014

et al. 2022

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We present relative astrometric and photometric measurements of visual double stars made in 2013-2014 with PISCO2 installed at the 76-cm refractor of the Côte d'Azur Observatory in Nice (France). Our observation list contains orbital couples as well as double stars whose motion is still uncertain. Three different techniques were used for obtaining measurements: Lucky Imaging, Speckle Interferometry, and the Direct Vector Autocorrelation method. From our observations of 4,864 multiple stars, we obtained 4,952 new measurements with angular separations in the range 0 ′′ .1-14 ′′ and an average accuracy of 0 ′′ .015. The mean error on the position angles is 1 • .0. 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 differences (up to Δm V ≈ 5). We have thus been able to measure 49 systems containing red dwarf stars that had been poorly monitored since their discovery, from which we estimated the stellar masses thanks to Gaia measurements. We also measured the magnitude difference of the two components of 318 double stars with an estimated error of 0.2 mag. Except for a few objects that have been discussed, our measurements are in good agreement with the ephemerides computed with published orbital elements, even for the double stars whose separation is smaller 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 455 measurements with an angular separation smaller than the diffraction limit of our instrumentation, and consistent with those obtained with larger telescopes. Finally, we report 378 measurements of the 296 new double stars that we found in the files obtained during the observations.

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Section: Data Reduction Proceduresmentioning

confidence: 99%

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014

et al. 2022

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“…Indeed, PSE belongs to the LI family where STF compensation is generally not made (see for example Garrel et al 2012). STF compensation could however be considered with PSE in the future, using either a modeling such as in Tokovinin (2010), or by subtracting the cross-spectrum of images separated by a temporal lag greater than the coherence time, as proposed by Worden et al (1977) and used routinely for speckle observations with the PISCO speckle camera Scardia et al (2019).…”

Section: The Methodsmentioning

confidence: 99%

Short-exposure Image Reconstruction with The Power Spectrum Extended (PSE) Method

Cottalorda¹,

Aristidi²,

Carbillet³

et al. 2022

PASP

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We analyze, in the framework of high angular resolution imaging, a novel image reconstruction method denoted as PSE (which stands for power spectrum extended). It works in the Fourier space, combining the information from both the average power spectrum of the images and a phase estimation from an ad-hoc shift-and-add process. PSE allows to perform image reconstruction up to the diffraction limit of the telescope from a series of short-exposure frames, with a refined lucky-imaging selection process. The method is well adapted to partially corrected adaptive-optics images, in particular in case of low Strehl corrections, and/or small diameter telescopes. In this paper we analyze the PSE technique by means of Monte-Carlo simulations and compare it with the ISFAS lucky-imaging method. Comparative performances were investigated using three metrics: Strehl ratio for reconstructed point-like sources, intensity ratio for binary stars, and least-square distance between images for a simulated artificial satellite. We found that PSE provides an improvement of a factor ∼2 over ISFAS on the Strehl ratio in the case of faint point sources. It seems also to give better images reconstruction on some kinds of extended objects (planets or binary stars with small magnitude difference). PSE has also the advantage to be very fast and well adapted to real-time image reconstruction.

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“…We also observed Kalliope in December 2021 with the Pupil Interferometry Speckle camera and COronagraph (PISCO, Scardia et al 2019) at the 1 m C2PU telescope in Calern, Observatoire de la Cote d'Azur (OCA) (Bendjoya et al 2012). Observations were carried out during the nights of December 30 and 31, 2021.…”

Section: Speckle Measurementsmentioning

confidence: 99%

M-type (22) Kalliope: A tiny Mercury

Ferrais

Jordá

Vernazza

et al. 2022

A&A

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Context. Asteroid (22) Kalliope is the second largest M-type asteroid in the main belt and is orbited by a satellite, Linus. Whereas the mass of Kalliope is already well constrained thanks to the presence of a moon, its volume is still poorly known, leading to uncertainties on its bulk density and internal structure. Aims. We aim to refine the shape of (22) Kalliope and thus its diameter and bulk density, as well as the orbit of its moon to better constrain its mass, hence density and internal structure. Methods. We acquired disk-resolved observations of (22) Kalliope using the VLT/SPHERE/ZIMPOL instrument to reconstruct its three-dimensional (3D) shape using three different modeling techniques. These images were also used together with new speckle observations at the C2PU/PISCO instrument as well as archival images from other large ground-based telescopes to refine the orbit of Linus. Results. The volume of (22) Kalliope given by the shape models, corresponding to D = 150 ± 5 km, and the mass constrained by its satellite’s orbit yield a density of ρ = 4.40 ± 0.46 g cm−3. This high density potentially makes (22) Kalliope the densest known small body in the Solar System. A macroporosity in the 10–25% range (as expected for this mass and size), implies a grain density in the 4.8–5.9 g cm−3 range. Kalliope’s high bulk density, along with its silicate-rich surface implied by its low radar albedo, implies a differentiated interior with metal contributing to most of the mass of the body. Conclusions. Kalliope’s high metal content (40–60%) along with its metal-poor mantle makes it the smallest known Mercury-like body. A large impact at the origin of the formation of the moon Linus is likely the cause of its high metal content and density.

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Speckle observations with PISCO in Calern (France): I. Astrometric measurements of visual binaries in 2015–2016

Cited by 8 publications

References 26 publications

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014

Measurements of visual double stars with PISCO2 at the Nice 76‐cm refractor in 2013–2014

Short-exposure Image Reconstruction with The Power Spectrum Extended (PSE) Method

M-type (22) Kalliope: A tiny Mercury

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