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3 results on '"Julio Camargo"'

1. The five largest satellites of Uranus: Astrometric observations spread over 29 years at the Pico dos Dias Observatory

Author

Marcelo Assafin, R. Vieira-Martins, C.H. Veiga, Agnes Fienga, and Julio Camargo

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), Physics, Solar System, Uranus, FOS: Physical sciences, Astronomy, Astronomy and Astrophysics, Astrometry, Ephemeris, Stars, Space and Planetary Science, Observatory, Orbit (dynamics), Astrophysics - Instrumentation and Methods for Astrophysics, Instrumentation and Methods for Astrophysics (astro-ph.IM), Data release, Astrophysics - Earth and Planetary Astrophysics
Abstract

We present the astrometry of the five largest satellites of Uranus from observations spread over almost three decades with photographic plates and CCDs (mainly), taken at the Pico dos Dias Observatory - Brazil. All positions presented here are obtained from the reanalysis of measurements and images used in previous publications. Reference stars are those from the Gaia Early Data Release 3 (Gaia EDR3) allowing, in addition to a higher accuracy, a larger number of positions of the largest satellites as compared to our previous works. From 1982 to 1987, positions were obtained from photographic plates. From 1989 to 2011, CCDs were used. On average, we obtained $\Delta\alpha{\rm cos}\delta=-11~(\pm52)$ milli-arcseconds and $\Delta\delta=-14~(\pm43)$ milli-arcseconds for the differences in the sense observation minus ephemerides (DE435$+$ura111). Comparisons with different ephemerides (DE440, INPOP21a, INPOP19a and NOE-7-2013-MAIN) and results from stellar occultations indicate a possible offset in the (Solar System) barycentric position of the Uranian system barycenter. Overall, our results are useful to improve dynamical models of the Uranian largest satellites as well as the orbit of Uranus., Comment: 16 pages, 13 figues, 9 tables

Published
2022

2. New insights on the binary Asteroid 121 Hermione

Author

Mikko Kaasalainen, P. Baudouin, Pascal Descamps, Franck Marchis, Raoul Behrend, Marcelo Assafin, Melissa C. Nysewander, J. B. Haislip, F. Manzini, Josh Emery, S. Sposetti, A. Peyrot, Daniel E. Reichart, Julio Camargo, Felipe Braga-Ribas, Alan W. Harris, Joe Pollock, K. M. Ivarsen, Roberto Vieira-Martins, F. Colas, Frédéric Vachier, L. Hutton, J. Greene, J. Lecacheux, L. Brunetto, Jérôme Berthier, Aaron P. LaCluyze, J. Durech, R. Roy, J. A. Crain, J.-P. Teng-Chuen-Yu, L. Bernasconi, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Centre National de la Recherche Scientifique (CNRS)-Université de Lille-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC), Department of Astronomy [Berkeley], University of California [Berkeley], University of California-University of California, SETI Institute, Astronomical Institute of Charles University, Charles University [Prague] (CU), Department of Earth and Planetary Sciences [Knoxville], The University of Tennessee [Knoxville], DLR Institute of Planetary Research, German Aerospace Center (DLR), Department of Mathematics and Statistics, Makes Observatory, Department of Physics and Astronomy [Boone], Appalachian State University, University of North Carolina System (UNC)-University of North Carolina System (UNC), Observatório do Valongo/UFRJ [Rio de Janeiro], Universidade Federal do Rio de Janeiro (UFRJ), Observatório Nacional/MCT, Observatório do Valongo, Universidade Federal do Rio de Janeiro Ladeira do Pedro Antônio, Department of Physics and Astronomy [Chapel Hill], University of North Carolina [Chapel Hill] (UNC), Geneva Observatory, University of Geneva [Switzerland], Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Les Engarouines Observatory, Blauvac Observatory, Harfleur Observatory, Chercheur indépendant, Gnosca Observatory, Stazione Astronomica di Sozzago, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), University of California [Berkeley] (UC Berkeley), University of California (UC)-University of California (UC), Université de Genève = University of Geneva (UNIGE), Institut de Mécanique Céleste et de Calcul des Ephémérides ( IMCCE ), Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université de Lille-Centre National de la Recherche Scientifique ( CNRS ), Astronomy Department [Berkeley], Charles University [Prague], German Aerospace Center ( DLR ), Department of Physics and Astronomy, Universidade Federal do Rio de Janeiro [Rio de Janeiro] ( UFRJ ), The University of North Carolina at Chapel Hill, Laboratoire d'études spatiales et d'instrumentation en astrophysique ( LESIA ), and Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Institut national des sciences de l'Univers ( INSU - CNRS ) -Observatoire de Paris-Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
Solar System, 010504 meteorology & atmospheric sciences, [PHYS.ASTR.EP]Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Eclipses, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Asteroids: rotation, Equinox, surfaces, eclipses, rotation, 01 natural sciences, law.invention, Photometry, Photometry (optics), Telescope, satellites, Spitzer Space Telescope, law, 0103 physical sciences, Adaptive optics, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Earth and Planetary Astrophysics (astro-ph.EP), Physics, Astronomy, Astronomy and Astrophysics, Light curve, [ SDU.ASTR.EP ] Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Asteroids, [ PHYS.ASTR.EP ] Physics [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], Space and Planetary Science, Asteroid, Satellites of Asteroids, Astrophysics - Earth and Planetary Astrophysics
Abstract

We report on the results of a six-month photometric study of the main-belt binary C-type asteroid 121 Hermione, performed during its 2007 opposition. We took advantage of the rare observational opportunity afforded by one of the annual equinoxes of Hermione occurring close to its opposition in June 2007. The equinox provides an edge-on aspect for an Earth-based observer, which is well suited to a thorough study of Hermione's physical characteristics. The catalog of observations carried out with small telescopes is presented in this work, together with new adaptive optics (AO) imaging obtained between 2005 and 2008 with the Yepun 8-m VLT telescope and the 10-m Keck telescope. The most striking result is confirmation that Hermione is a bifurcated and elongated body, as suggested by Marchis et al., (2005). A new effective diameter of 187 +/- 6 km was calculated from the combination of AO, photometric and thermal observations. The new diameter is some 10% smaller than the hitherto accepted radiometric diameter based on IRAS data. The reason for the discrepancy is that IRAS viewed the system almost pole-on. New thermal observations with the Spitzer Space Telescope agree with the diameter derived from AO and lightcurve observations. On the basis of the new AO astrometric observations of the small 32-km diameter satellite we have refined the orbit solution and derived a new value of the bulk density of Hermione of 1.4 +0.5/-0.2 g cm-3. We infer a macroscopic porosity of ~33 +5/-20%., Comment: 39 pages, 4 Tables, 8 figures

Published
2009

3. Instrumental and digital coronagraphy for the observation of the Uranus satellites’ upcoming mutual events

Author

A. H. Andrei, R. Vieira Martins, D. N. da Silva Neto, Julio Camargo, R.P. Campos, Marcelo Assafin, Observatório do Valongo, Universidade Federal do Rio de Janeiro, Laboratório Nacional de Astrofísica, Observatório Nacional/MCTI, Institut de Mécanique Céleste et de Calcul des Ephémérides (IMCCE), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS), Groupe Astrométrie et Planétologie (GAP), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris

Subjects
Physics, Brightness, Astrophysics::Instrumentation and Methods for Astrophysics, Uranus, Astronomy, Astronomy and Astrophysics, Astrometry, law.invention, Telescope, Photometry (optics), Space and Planetary Science, law, Planet, Physics::Space Physics, Satellite, Astrophysics::Earth and Planetary Astrophysics, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Coronagraph
Abstract

Ground-based observations of faint satellites nearby their planets with 1–2 m class telescopes usually do not allow for high quality astrometry and photometry, due to saturation by the primary or to poor S/N ratio on the satellite images, generally embedded on the scattered light of the planet. Earth-based observations of the Uranus satellites’ upcoming mutual events in 2007–2008 are no exception. In most cases, the event will take place at 4 arcs or less from the planet, with “planet minus satellite” brightness differences of 10 magnitudes. So as to make feasible the observations of these important phenomena, we have developed a prototype of a coronagraph of simple design making use of good quality commercial optical systems. Pilot tests made with this coronagraph with a telescope of D = 1.6 m show that it is possible to obtain S/N ratios of 50 or higher for 10 s exposures, for satellites as close as 2 Uranus radii from the planet center. We have also developed numerical algorithms which perform digital coronagraphy in the images, with the elimination of the influence of the planets’ scattered light. This procedure considerably improves the S/N ratio of the satellite images (with or without a coronagraph instrument) and shall be applied in the reduction of the observations of the Uranus events so as to achieve the highest possible photometric and astrometric quality.

Published
2008

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