Now showing items 1-20 of 42

    • Analysis of the Bayesian Cramer-Rao lower bound in astrometry Studying the impact of prior information in the location of an object 

      Echeverría Solis, Alex; Silva Sánchez, Jorge; Méndez Bussard, René Alejandro; Orchard Concha, Marcos (EDP Sciences, 2016)
      Context. The best precision that can be achieved to estimate the location of a stellar-like object is a topic of permanent interest in the astrometric community. Aims. We analyze bounds for the best position estimation ...
    • Analysis of the Cramér-Rao Bound in the Joint Estimation of Astrometry and Photometry 

      Méndez Bussard, René Alejandro; Silva Sánchez, Jorge; Oróstica, Rodrigo; Lobos, Rodrigo (The Astronomical Society of the Pacific, 2014)
      In this paper, we use the Cramér-Rao lower uncertainty bound to estimate the maximum precision that could be achieved on the joint simultaneous (or two-dimensional) estimation of photometry and astrometry of a point source ...
    • Basic parameters of three star clusters in the Small Magellanic Cloud: Kron 11, Kron 63 and NGC 121 

      Baume, Gustavo; Noel, Noelia E. D.; Costa Hechenleitner, Edgardo; Carraro, Giovanni; Méndez Bussard, René Alejandro; Pedreros, M. H. (BLACKWELL, 2008-11-11)
      We present observations for three star clusters, Kron 11, Kron 63 and NGC 121, in the Small Magellanic Cloud. We have studied their structure and derived their fundamental parameters by means of their luminosity functions, ...
    • Characterizing the astrometric precision limit for moving targets observed with digital-array detectors 

      Bouquillon, S.; Méndez Bussard, René Alejandro; Altmann, M.; Carlucci, T.; Barache, C.; Taris, F.; Andrei, A. H.; Smart, R. (EDP Sciences, 2017)
      Aims. We investigate the maximum astrometric precision that can be reached on moving targets observed with digital-sensor arrays, and provide an estimate for its ultimate lower limit based on the Cramer-Rao bound. Methods. ...
    • The chemical enrichment history of the small magellanic cloud and its gradients 

      Carrera, Ricardo; Gallart, Carme; Aparicio, Antonio; Costa Hechenleitner, Edgardo; Méndez Bussard, René Alejandro; Noel, Noelia E. D. (IOP PUBLISHING, 2008-09)
      We present stellar metallicities derived from Ca II triplet spectroscopy in over 350 red giant branch stars in 13 fields distributed in different positions in the Small Magellanic Cloud, ranging from similar to 1 degrees ...
    • A comprehensive view of the Virgo stellar stream 

      Duffau, Sonia; Vivas, A. Katherina.; Zinn, Robert; Méndez Bussard, René Alejandro; Ruiz González, María Teresa (2014)
      To explore the complex halo substructure that has been reported in the direction of the Virgo constellation, radial velocities and metallicities have been measured for 82 RR Lyrae stars (RRLS) that were identified by the ...
    • Extended star formation history of the star cluster NGC 2154 in the Large Magellanic Cloud 

      Baume, Gustavo; Carraro, Giovanni; Costa Hechenleitner, Edgardo; Méndez Bussard, René Alejandro; Girardi, L. (2007)
      The colour–magnitude diagram (CMD) of the intermediate-age Large Magellanic Cloud star cluster NGC 2154 and its adjacent field has been analysed using Padova stellar models to determine the cluster’s fundamental parameters ...
    • In-situ star formation in the outskirts of the large magellanic cloud: Gaia DR2 confirmation 

      Casetti-Dinescu, Dana I.; Girard, Terrence M.; Moni Bidin, Christian; Zhang, Lan; Méndez Bussard, René Alejandro; Vieira, Katherine; Korchagin, Vladimir I.; Van Altena, William F. (IOP Publishing, 2018-07-20)
      We explore the Gaia data release 2 (DR2) proper motions of six young, main-sequence stars, members of the Large Magellanic Cloud (LMC) reported by Moni Bidin et al. These stars are located in the outskirts of the disk, ...
    • KINEMATICAL AND CHEMICAL VERTICAL STRUCTURE OF THE GALACTIC THICK DISK. II. A LACK OF DARK MATTER IN THE SOLAR NEIGHBORHOOD 

      Moni Bidin, Christian; Carraro, Giovanni; Méndez Bussard, René Alejandro; Smith, R. (IOP PUBLISHING LTD, 2012-05-20)
      We estimated the dynamical surface mass density Sigma at the solar position between Z = 1.5 and 4 kpc from the Galactic plane, as inferred from the kinematics of thick disk stars. The formulation is exact within the limit ...
    • The multiwavelength survey by Yale-Chile (MUSYC): Survey design and deep public UBVRIZ ' images and catalogs of the extended Hubble Deep Field-South 

      Gawiser, Eric; van Dokkum, Pieter; Herrera, David; Maza Sancho, José; Castander, Francisco; Infante, Leopoldo; Lira Teillery, Paulina; Quadri, Ryan; Toner, Ruth; Treister, Ezequiel; Urry, C. Megan; Altmann, Martin; Assef, Roberto; Christlein, Daniel; Coppi, Paolo S.; Durán, María Fernanda; Franx, Marijn; Galaz, Gaspar, 1967-; Huerta, Leonor; Liu, Charles; López Morales, Sebastián; Méndez Bussard, René Alejandro; Moore, David C.; Rubio López, Mónica; Ruiz González, María Teresa; Toft, Sune; Yi, Sukyoung K. (UNIV CHICAGO PRESS, 2006-01)
      We present UBVRIz' optical images taken with MOSAIC on the CTIO 4 m telescope of the 0.32 deg(2) Extended Hubble Deep Field-South. This is one of four fields comprising the MUSYC survey, which is optimized for the study ...
    • New radial systems of dark globules 

      Gyulbudaghian, A. L.; Méndez Bussard, René Alejandro (UNAM, Instituto de Astronomía, 2015)
      We present the results of a systematic survey of ESO/SRC plates of the Southern Hemisphere aimed at discovering new radial systems of dark globules. During this survey, we found 16 new type 1 radial systems and 6 type 2 ...
    • NGC 6404 and 6583: two neglected intermediate-age open clusters located in the Galactic Centre direction 

      Carraro, Giovanni; Méndez Bussard, René Alejandro; Costa Hechenleitner, Edgardo (2005)
      We report on VI charge-coupled device photometry of two fields centred in the region of the open clusters NGC 6404 and 6583 down to V = 22.0. So far these clusters have never been studied, and we provide for the first time ...
    • NPARSEC: NTT Parallaxes of Southern Extremely Cool objects. Goals, targets, procedures and first results 

      Smart, R. L.; Tinney, C. G.; Bucciarelli, B.; Marocco, F.; Abbas, U.; Andrei, A.; Bernardi, G.; Burningham, B.; Cardoso, C.; Costa Hechenleitner, Edgardo; Crosta, M. T.; Daprá, A.; Day Jones, A.; Goldman, B.; Jones, H. R.; Lattanzi, M. G.; Leggett, S. K.; Lucas, P.; Méndez Bussard, René Alejandro; Penna, J. L.; Pinfield, D.; Smith, L.; Sozzetti, A.; Vecchiato, A. (Oxford University Press on behalf of the Royal Astronomical Society, 2013)
      The discovery and subsequent detailed study of T dwarfs have provided many surprises and pushed the physics and modelling of cool atmospheres in unpredicted directions. Distance is a critical parameter for studies of ...
    • Old main-sequence turnoff photometry in the small magellanic cloud. I. Constraints on the star formation history in different fields 

      Noel, Noelia E. D.; Gallart, Carme; Costa Hechenleitner, Edgardo; Méndez Bussard, René Alejandro (2007)
      We present ground-based B-and R-band color-magnitude diagrams (CMDs) reaching the oldest main-sequence (MS) turnoffs with good photometric accuracy for 12 fields in the Small Magellanic Cloud (SMC). Our fields, located ...
    • On the local dark matter density 

      Moni Bidin, C.; Smith, R.; Carraro, Giovanni; Méndez Bussard, René Alejandro; Moyano, M. (EDP SCIENCES, 2015)
      Context. In 2012, we applied a three-dimensional formulation to kinematic measurements of the Galactic thick disk and derived a surprisingly low dark matter density at the solar position. This result was challenged by Bovy ...
    • On the local dark matter density 

      Méndez Bussard, René Alejandro; Bidin, Mondi; Smith, R.; Carraro, Giovanni; Moyano, M. (2015)
      Context. In 2012, we applied a three-dimensional formulation to kinematic measurements of the Galactic thick disk and derived a surprisingly low dark matter density at the solar position. This result was challenged by ...
    • Orbits for eighteen visual binaries and two double-line spectroscopic binaries observed with hrcam on the CTIO SOAR 4m telescope, using a new bayesian orbit code based on markov chain Monte Carlo 

      Méndez Bussard, René Alejandro; Claveria, Ruben M.; Orchard Concha, Marcos; Silva, Jorge F. (IOP Publishing Ltd., 2017)
      We present orbital elements and mass sums for 18 visual binary stars of spectral types B to K (five of which are new orbits) with periods ranging from 20 to more than 500 yr. For two double-line spectroscopic binaries with ...
    • Performance Analysis of the Least-Squares Estimator in Astrometry 

      Lobos, Rodrigo A.; Silva, Jorge F.; Méndez Bussard, René Alejandro; Orchard Concha, Marcos (Univ Chicago Press, 2015)
      We characterize the performance of the widely used least-squares estimator in astrometry in terms of a comparison with the Cramer-Rao lower variance bound. In this inference context the performance of the least-squares ...
    • Performance Analysis of the Least-Squares Estimator in Astrometry 

      Lobos, Rodrigo; Silva, Jorge; Méndez Bussard, René Alejandro; Orchard Concha, Marcos (The Astronomical Society of the Pacific, 2015-11)
      We characterize the performance of the widely used least-squares estimator in astrometry in terms of a comparison with the Cramér–Rao lower variance bound. In this inference context the performance of the leastsquares estimator ...
    • Photometric parallaxes of Southern high proper motion stars. I. 

      Costa Hechenleitner, Edgardo; Méndez Bussard, René Alejandro (2003)
      Photometric distances derived from VRI photometry are given for 44 high proper motion stars from the Cerro El Roble proper motion surveys of Wroblewski & Torres and Wroblewski & Costa. The observations were carried out ...