898 resultados para Sergio Ramírez


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We present the results of the analysis of satellite imagery to study light pollution in Spain. Both calibrated and non-calibrated DMSP-OLS images were used. We describe the method to scale the non-calibrated DMSP-OLS images which allows us to use differential photometry techniques in order to study the evolution of the light pollution. Population data and DMSP-OLS satellite calibrated images for the year 2006 were compared to test the reliability of official statistics in public lighting consumption. We found a relationship between the population and the energy consumption which is valid for several regions. Finally the true evolution of the electricity consumption for street lighting in Spain from 1992 to 2010 was derived; it has been doubled in the last 18 years in most of the provinces. (C) 2013 Elsevier Ltd. All rights reserved,

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In these proceedings we summarize the characteristics and current status of MEGARA, the future optical IFU and MOS for the 10.4 m GTC. MEGARA is being built by a Consortium led by the UCM (Spain) that also includes the INAOE (Mexico), the IAA-CSIC (Spain) and the UPM (Spain). The MEGARA IFU offers two different bundles, one called LCB with a field-of-view of 14 x 12 arcsec^2 and a spaxel size of 0.685 arcsec yielding spectral resolutions between R=6000-19000 and another one called SCB covering 10 x 8 arcsec^2 with 0.48 arcsec spaxels and resolutions R=8000-25000. The MOS component allows observing up to 100 targets in 3.5x3.5 arcmin^2. In September 2010 MEGARA was selected as the next optical spectrograph for GTC. Its PDR is scheduled for March 2012 with First Light on 2015.

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The UCM Instrumentation Group (GUAIX) is developing currently Data Reduction Pipelines (DRP) for four instruments of the GTC: EMIR, FRIDA, MEGARA and MIRADAS. The purpose of the DRPs is to provide astronomers scientific quality data, removing instrumental biases, calibrating the images in physical units and providing a estimation of the associated uncertainties.

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MEGARA (Multi-Espectrografo en GTC de Alta Resolucion para Astronomia) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4 m telescope in La Palma. The MEGARA Control System will provide the capabilities to move the different mechanisms of the instrument, to readout the data from the detector controller and the necessary routines for the Inspector Panels, the MEGARA Observing Preparation Software Suite, the Data Factory and the Sequencer strategies.

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MEGARA (Multi-Espectrografo en GTC de Alta Resolucion para Astronomia) is an optical Integral-Field Unit (IFU) and Multi-Object Spectrograph (MOS) designed for the GTC 10.4 m telescope in La Palma. Its relatively complex layout makes necessary a set of tools to facilitate the observation preparation to the user. The MEGARA Observing Preparation Software Suite (MOPSS) consists on three software components designed to assist observers to optimally plan their observations with GTC/MEGARA: the Exposure Time Calculator, the Image Simulator, and the Fiber MOS Positioning tool. We describe these software tools and the status of their prototypes up to the date.

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LICA-UCM is the brand new laboratory for scientific advanced instrumentation (Laboratorio de Investigacion Cientifica Avanzada) at Universidad Complutense de Madrid where MEGARA integration will take place.

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Context. Although many studies have been performed so far, there are still dozens of low-mass stars and brown dwarfs in the young σ Orionis open cluster without detailed spectroscopic characterisation. Aims. We look for unknown strong accretors and disc hosts that were undetected in previous surveys. Methods. We collected low-resolution spectroscopy (R ~ 700) of ten low-mass stars and brown dwarfs in σ Orionis with OSIRIS at the Gran Telescopio Canarias under very poor weather conditions. These objects display variability in the optical, infrared, Hα, and/or X-rays on time scales of hours to years. We complemented our spectra with optical and near-/mid-infrared photometry. Results. For seven targets, we detected lithium in absorption, identified Hα, the calcium doublet, and forbidden lines in emission, and/or determined spectral types for the first time. We characterise in detail a faint, T Tauri-like brown dwarf with an 18 h-period variability in the optical and a large Hα equivalent width of –125  ±  15 Å, as well as two M1-type, X-ray-flaring, low-mass stars, one with a warm disc and forbidden emission lines, the other with a previously unknown cold disc with a large inner hole. Conclusions. New unrevealed strong accretors and disc hosts, even below the substellar limit, await discovery among the list of known σ Orionis stars and brown dwarfs that are variable in the optical and have no detailed spectroscopic characterisation yet.

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EMIR (Balcells et al. 2000) is a near-infrared wide-field camera and multi-object spectrograph being built for the GTC. The Data Reduction Pipeline (DRP) will be optimized for handling and reducing near-infrared data acquired with EMIR.

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Emission line galaxies are the most easily detected and studied objects in the high redshift Universe. They are being used to trace the evolution of critical observables of the Universe such as Star Formation Rate densities, starburst properties and abundances. Most of the research is being done using [OII]3727 and UV lines, but Hα is still one the best tracers for Star Formation Rate and physical properties of current star-forming galaxies. As a complementary contribution to studies of galaxy evolution, our team has focused into a long-term project to study the population of Hα-selected star-forming galaxies of the Universe at different redshifts. In 1995 we first determined the local Hα luminosity function, and from it the Star Formation Rate density (SFRd) of the local Universe. We then, using narrow-band imaging in the optical, extended this measurement to z ≃ 0.24 and z ≃ 0.4. Working in the near-infrared, GTC will be a very powerful tool to study the evolution of the Hα emission-line galaxy populations at different redshifts. We will both quantify the SFRd evolution and characterize the star-forming galaxy populations by directly comparing the same observables at all redshifts up to z ≃ 2.5.

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We present NH_3(1,1) and (2,2) observations of MBM 12, the closest known molecular cloud (65-pc distance), aimed at finding evidence for on-going star formation processes, No local temperature (with a T_rot upper limit of 12 K) or linewidth enhancement is found, which suggests that the area of the cloud that we have mapped (∼ 15-arcmin size) is not currently forming stars. Therefore this nearby 'starless' molecular gas region is an ideal laboratory to study the physical conditions preceding new star formation. A radio continuum source has been found in Very Large Array archive data, close to but outside the NH_3 emission. This source is likely to be a background object.

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Terrestrial mammals are good dispersers of the fruits and seeds of seasonal rainforest in the Gulf of Mexico. Their importance lies in the huge quantity of fruit and seeds they consume, and their daily and seasonal movement through natural and secondary vegetation and agricultural fields. Their importance is even more noteworthy in the face of increasing deforestation and forest fragmentation, which limits the dispersal of propagules across the landscape and affects, among other things, the potential for forest regeneration. To evaluate fruit and seed consumption and dispersal over 12 months, the droppings of rainforest mammals were analyzed for the rainforest and an abandoned pasture (8,400 m2 respectively) on the coast of central Veracruz, Mexico. In the rainforest 158 droppings were collected and 47 in the pasture from a total of eight mammal species, six of which are known dispersers. The droppings contained 150 seeds belonging to 36 species and 19 families. The deposition of different species and quantities of seeds in the forest and pasture indicates that mammals disperse more rainforest species to the pasture than vice versa.

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Fil: Chicote, Gloria. Universidad Nacional de La Plata. Facultad de Humanidades y Ciencias de la Educación. Instituto de Investigaciones en Humanidades y Ciencias Sociales (UNLP-CONICET); Argentina.