L’influence de la couleur dans les mécanismes perceptuels et attentionnels a été étudiée. Quatre couleurs (le rouge, le vert, le bleu et le jaune) ont été calibrées individuellement à travers la technique heterochromatic flicker photometry. Suivant cela, les participants ont déployé leur attention à une cible (un cercle de couleur avec une ligne orientée). Les données électrophysiologiques ont été enregistrées pendant que les sujets performaient la tâche de recherche visuelle, et les analyses ont été basées sur les potentiels évoqués (PÉs). Trois composantes des PÉs ont été examinées : la posterior contralateral positivity (Ppc); la N2pc, reflétant le déploiement de l’attention visuo-spatiale et la temporal and contralateral positivity (Ptc). Des conditions dans lesquelles la cible était bleu ou rouge, lorsque comparées à des conditions avec une cible jaune ou verte suscitaient une N2pc plus précoce. Une amplitude plus élevée est aussi observée pour les cibles rouges pour les composantes Ppc et Ptc, reflétant une sélectivité pré-attentionelle. Ces résultats suggèrent de la prudence dans l’interprétation de données comparant des cibles de différentes couleurs dans des tâches de PÉs, et ce même lorsque les couleurs sont équiluminantes. / We investigated how target color affected behavioral and electrophysiological results in a visual search task. Perceptual and attentional mechanisms were tracked using the N2pc component of the event-related potential and other lateralized components. Four colors (red, green, blue, or yellow) were calibrated for each participant for luminance through heterochromatic flicker photometry and equated to the luminance of grey distractors. Each visual display contained 10 circles, 1 colored and 9 grey, each of which contained an oriented line segment. The task required deploying attention to the colored circle, which was either in the left or right visual hemifield. Three lateralized ERP components relative to the side of the lateral colored circle were examined: a posterior contralateral positivity (Ppc) prior to N2pc, the N2pc, reflecting the deployment of visual spatial attention, and a temporal and contralateral positivity (Ptc) following N2pc. Red or blue stimuli, as compared to green or yellow, had an earlier N2pc. Both the Ppc and Ptc had higher amplitudes to red stimuli, suggesting particular selectivity for red. The results suggest that attention may be deployed to red and blue more quickly than to other colors and suggests special caution when designing ERP experiments involving stimuli in different colors, even when all colors are equiluminant.

A avaliação dos efeitos dos aerossóis em relação ao balanço radiativo local e global bem como o impacto sobre a saúde humana, principalmente em grandes centros urbanos, demanda que se conheça de forma precisa a sua concentração e distribuição espaço-temporal. Neste contexto, o monitoramento acurado de longo prazo por estações instaladas ao redor do mundo tornou-se um desafio e uma necessidade para várias áreas do conhecimento. Classicamente as estações utilizam a técnica de fotometria solar para inferir a concentração e a distribuição de tamanho dos aerossóis através da profundidade óptica do aerossol (POA) e do coeficiente de Ångström . No presente trabalho é sugerida uma metodologia para estimar POA e do coeficiente de Ångström através de quatro canais espectrais de radiômetros do tipo Multi-Filter Rotating Shadowband Radiometer (MFRSR) que operam em São Paulo desde 1999. Estas estimativas foram avaliadas em relação à rede AErosol RObotic NETwork (AERONET) entre os anos de 2004 a 2006. Os resultados mostram que, em termos de variabilidade temporal da POA, há boa concordância entre os diferentes instrumentos. Entretanto, são encontradas diferenças médias sistemáticas da ordem de 0,03 na magnitude da POA em três dos quatro canais analisados, enquanto que o valor sugerido pela OMM para uma atmosfera limpa é de no máximo 0,02. Este resultado aponta que a metodologia empregada nos MFRSR fornece valores de boa qualidade. Ainda neste trabalho, foram relacionadas variáveis meteorológicas coletadas pela Estação Meteorológica do IAG-USP com a POA e o do coeficiente de Ångström estimados neste trabalho. Observou-se uma relação linear entre o coeficiente de Ångström e a umidade relativa (UR), indicando um crescimento do tamanho médio dos aerossóis que integram um grupo com 0,20<POA<=0,60 no canal 415nm com o aumento da umidade relativa. Acredita-se que este grupo tenha predominância de aerossóis de fontes locais. As medidas de longo prazo permitiram também caracterizar, em conjunto com estimativas espaciais de POA pelo sensor Moderate Resolution Imaging Spectroradiometer (MODIS) a bordo do satélite Terra, a influência do transporte de aerossóis de queimadas da região amazônica e do Brasil central em São Paulo, na série de dados analisados. Estes eventos contribuem para o aumento significativo da POA sobre a região metropolitana e trazem partículas ligeiramente menores que as emitidas por fontes locais. / The evaluation of the aerosol effects to the local and global radiation budget, as well as the impact on human health, particularly in large urban centers, demands knowing accurately their concentration and spatial-temporal distribution. In this context, the accurate long term monitoring from ground based stations installed around the world has become a challenge and a necessity for various areas of knowledge. Classically, the stations use the technique of Sun photometry to infer the concentration and size distribution of aerosols through the aerosol optical depth (AOD) and Ångström coefficient . In this paper we suggest a methodology to estimate AOD and Ångström coefficient through four channels of Multi-Filter Rotating Shadowband Radiometers (MFRSR) operating in Sao Paulo since 1999. These estimates were compared to the results of the AErosol RObotic NETwork (AERONET) between the years of 2004 to 2006. The results showed that the MFRSR can represent well the temporal variability of the AOD, but systematic differences were found with mean values of about 0.03 in AOD, in three of the four analyzed channels. The value suggested by WMO for clean air is at most 0.02. This result indicates that the methodology employed in MFRSR provides values of quality good. Also in this study, meteorological influences on the aerosol optical properties were analyzed. The meteorological variables were monitored at the Meteorological Station of the IAG-USP There was a linear relationship between Ångström coefficient and relative humidity (RH), indicating a growth of the average size of aerosols within a group with 0.20<AOD<=0.60, in the channel 415 nm, with increasing relative humidity. It is believed that this group has predominance of aerosols from local sources. Long term measurements also helped to characterize, together with spatial estimates of AOD by the Moderate Resolution Imaging Spectroradiometer (MODIS) on board the Terra satellite, the influence of the transport of aerosol particles from biomass burning from the Amazon region to São Paulo. It was observed that these events contribute to significant increase in AOD on the metropolitan region and bring slightly smaller particles than the emitted by local sources.

Esse trabalho tem como objetivo o desenvolvimento de procedimentos analíticos automáticos, empregando o processo de multicomutação em fluxo para determinação espectrofotométrica de cobalto e cádmio em amostras de águas. O trabalho envolveu o desenvolvimento dos módulos de análises para implementar os procedimentos analíticos baseados no processo de multicomutação, o sistema de detecção fotométrica empregando LED como fonte de radiação eletromagnética, o software para controle do módulo de análise e para efetuar aquisição de dados. O módulo de análise para determinação de cobalto foi desenvolvido, utilizando mini-bombas solenóide para o bombeamento das soluções. O procedimento analítico foi baseado na catálise do cobalto na reação de oxidação do Tiron pelo peróxido de hidrogênio e com o sistema de detecção espectrofotométrica com LED com emissão em 425 nm. Após os ajustes necessários do módulo de análise o sistema apresentou bom desempenho analítico. Para a determinação de cobalto em águas foram obtidas as seguintes características analíticas: desvio padrão relativo de 0,04 % (n = 13) para uma amostra com 0,5 &micro;gL-1 de Co, faixa de resposta linear entre 0,13 a 1,5 &micro;gL-1 de Co (R = 0,998, n = 3), limite de detecção de 0,06 µgL-1, frequência analítica de 42 determinações por hora e geração de 1,5 mL de resíduo por determinação. Recuperações entre 84 e 114 % foram obtidas com adição de Co (II) nas amostras de águas. O módulo de análise para determinação cádmio foi desenvolvido e otimizado utilizando duas mini-bombas peristálticas para bombeamento das soluções e esvaziamento do percurso, uma válvula solenoide de três vias e três válvulas solenoide de duas vias, uma cela de fluxo com longo caminho óptico (100 mm) e LED com emissão em 520 nm. O procedimento analítico para a determinação do cádmio foi baseado na formação do complexo pelo Cd (II) com o reagente ditizona em meio micelar com o surfactante Triton X100. O procedimento apresentou faixa de resposta linear de 15,0 a 175,0 &micro;gL-1 de Cd (R = 0,997; n = 3), limite de detecção de 12,5 &micro;gL-1, desvio padrão relativo de 0,57 % (n = 10) para uma amostra de 30 &micro;gL-1 e frequência analítica de 43 amostras por hora. Recuperações entre 84 e 112 % foram obtidas com adição de Cd (II) nas amostras de águas. / This work deals with the development of automatic analytical procedures, based on multicommuted flow analysis process for spectrophotometric determination of cobalt and cadmium in water samples. The work involved the development of the analytical modules and the photometric detector using LEDs as electromagnetic radiation sources. The software to control the flow analysis module and to perform data acquisition, were developed using Quick BASIC4.5 as programming language. The analysis module for cobalt determination, employed solenoid mini-pumps for solutions pumping. The procedure was based on the cobalt catalytic effect on the Tiron oxidation by hydrogen peroxide and the photometric detection at 425 nm. After the necessary adjustments of the flow analysis module, the system showed good analytical performance. The following analytical characteristics for determination of cobalt in water were obtained: a relative standard deviation of 0.04% (n = 13) for a standard solution 0.5 &micro;gL-1 Co, a linear response ranging from 0.13 to 1.5 &micro;gL-1 Co (R = 0.998, n = 3), a detection limit of 0.06 &micro;gL-1, analytical frequency of 42 samples determination per hour and a waste generation of 1.5 mL per determination. Recoveries between 84 and 114% were obtained with the addition of Co (II) in water samples. The analytical module for determination of cadmium was developed, using two peristaltic mini-pumps and solenoid valves. The LED based photometer was furnished with a flow cell of long optical path (100 mm) and a LED with maximum emission at 520 nm. The flow analysis module was assembled with ability to perform a closed loop strategy, which was implemented to improve sensitivity. The analytical procedure for the determination of cadmium was based on reaction of Cd (II) with dithizone in a micelle medium with the surfactant Triton X-100. The procedure showed a linear response ranging from 15.0 to 175.0 &micro;gL-1 Cd (R = 0.997; n = 3), detection limit of 12.5 &micro;gL-1, RSD 0.57% (n = 10) for a sample of 30 &micro;gL-1 and analytical frequency of 43 samples per hour. Recoveries between 84 and 112% were obtained with addition of Cd (II) in water samples.

Submitted by Angela Maria de Oliveira (amolivei@uepg.br) on 2018-10-09T12:41:56Z No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Jessica Mayara Eidam.pdf: 7618711 bytes, checksum: 8899a404c0b09be99db22ac7f334ae5b (MD5) / Made available in DSpace on 2018-10-09T12:41:56Z (GMT). No. of bitstreams: 2 license_rdf: 811 bytes, checksum: e39d27027a6cc9cb039ad269a5db8e34 (MD5) Jessica Mayara Eidam.pdf: 7618711 bytes, checksum: 8899a404c0b09be99db22ac7f334ae5b (MD5) Previous issue date: 2018-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Buscando melhorar a estatística de parâmetros sismológicos de estrelas do tipoA,apresentamosnestetrabalhoaanálisededadosespectroscópicosefotométricos de oito estrelas observadas na direção do Pólo Galáctico durante a Campanha 8 da missão Kepler K2, proposto pelo nosso grupo de pesquisa. A observação fotométrica pelo satélite espacial Kepler ocorreu entre janeiro e março de 2016. A análise das frequências das oito curvas de luz foi feita usando o algoritmo CLEANEST e Period04. A espectroscopia de solo foi feita no OPD/LNA em outubro de 2015 com o telescópio Zeiss (0,6m) e em agosto de 2016 com o telescópio Perkin-Elmer (1,6m).Informaçõesespectroscópicascompletamosdadosdascurvasdeluzdosatélite, permitindo a caracterização da estrutura interna das estrelas. A determinação dos parâmetros estelares foi realizada por meio do Spectroscopy Made Easy (SME). Parâmetros como massa, raio e luminosidade foram obtidos usando as grades Code dÉvolution Stellaire Adaptatif et Modulaire (CESAM) e Porto Oscillations Code (POSC). Permitindo assim, gerar o modelo evolutivo para as oito estrelas. Estrelas dotipoespectralBmuitasvezessãoerroneamenteclassificadascomoestrelasdotipo espectralA,quandosomentedadosdefotometriasãoutilizadosparaaclassificação. Como exemplo, temos as estrelas: Epic220679442 e Epic220607132. Classificadas fotométricamente como tipo espectral A0, revelaram através da análise espectral, tratar-se do tipo espectral B9V. Epic220532854 é uma binária, Epic220466722 é uma δ e Epic220679442 possue variações fotométrica e, dados de espectroscopia revelam linha de Silício pronunciada (SiII λ4128), característica apresentada pela classe peculiar de estrelas Bp magnética. / Searching to improve the statistics of seismological parameters of stars of type A, we this work we present the analysis of spectroscopic and photometric data of eight stars observed in the direction of the Galactic Pole during the Kepler mission Campaign 8, proposed by our research group. The photometric observation occurred between January and March 2016. Frequency analysis of the eight light curves was made using the CLEANEST and Period04 algorithm. In addition to the photometric data, ground-based spectroscopy was done at the OPD/LNA in October 2015 with the Zeiss Telescope (0.6m) and in August 2016 with the Perkin-Elmer Telescope (1.6m). Spectroscopic information enhances the data from thesatellite’slightcurves,allowingthecharacterizationoftheinternalstellarstructure. Spectral characterization was done using Spectroscopy Made Easy (SME). Parameters such as mass, radius and luminosity were obtained using the Code d Évolution Stellaire Adaptatif et Modulaire (CESAM) and Porto Oscillations Code (POSC) grids, allowing to generate evolutionary models for the eight stars. Stars of spectral type B are often erroneously classified as stars of spectral type A, when only photometry data is used for classification. As an example, we have the stars: Epic220679442 and Epic220607132. Photometrically classified as spectral type A0, revealed through spectral analysis, to be spectral type B9V. Epic220532854 is a binary, Epic220466722 is a δ Scuti and Epic220679442 has photometric variations and spectroscopy data reveals pronounced silicon line (SiII λ4128), characteristic presented by the class peculiar stars Ap magnetic.

Esse trabalho tem como objetivo o desenvolvimento de procedimentos analíticos automáticos, empregando o processo de multicomutação em fluxo para determinação espectrofotométrica de cobalto e cádmio em amostras de águas. O trabalho envolveu o desenvolvimento dos módulos de análises para implementar os procedimentos analíticos baseados no processo de multicomutação, o sistema de detecção fotométrica empregando LED como fonte de radiação eletromagnética, o software para controle do módulo de análise e para efetuar aquisição de dados. O módulo de análise para determinação de cobalto foi desenvolvido, utilizando mini-bombas solenóide para o bombeamento das soluções. O procedimento analítico foi baseado na catálise do cobalto na reação de oxidação do Tiron pelo peróxido de hidrogênio e com o sistema de detecção espectrofotométrica com LED com emissão em 425 nm. Após os ajustes necessários do módulo de análise o sistema apresentou bom desempenho analítico. Para a determinação de cobalto em águas foram obtidas as seguintes características analíticas: desvio padrão relativo de 0,04 % (n = 13) para uma amostra com 0,5 &micro;gL-1 de Co, faixa de resposta linear entre 0,13 a 1,5 &micro;gL-1 de Co (R = 0,998, n = 3), limite de detecção de 0,06 µgL-1, frequência analítica de 42 determinações por hora e geração de 1,5 mL de resíduo por determinação. Recuperações entre 84 e 114 % foram obtidas com adição de Co (II) nas amostras de águas. O módulo de análise para determinação cádmio foi desenvolvido e otimizado utilizando duas mini-bombas peristálticas para bombeamento das soluções e esvaziamento do percurso, uma válvula solenoide de três vias e três válvulas solenoide de duas vias, uma cela de fluxo com longo caminho óptico (100 mm) e LED com emissão em 520 nm. O procedimento analítico para a determinação do cádmio foi baseado na formação do complexo pelo Cd (II) com o reagente ditizona em meio micelar com o surfactante Triton X100. O procedimento apresentou faixa de resposta linear de 15,0 a 175,0 &micro;gL-1 de Cd (R = 0,997; n = 3), limite de detecção de 12,5 &micro;gL-1, desvio padrão relativo de 0,57 % (n = 10) para uma amostra de 30 &micro;gL-1 e frequência analítica de 43 amostras por hora. Recuperações entre 84 e 112 % foram obtidas com adição de Cd (II) nas amostras de águas. / This work deals with the development of automatic analytical procedures, based on multicommuted flow analysis process for spectrophotometric determination of cobalt and cadmium in water samples. The work involved the development of the analytical modules and the photometric detector using LEDs as electromagnetic radiation sources. The software to control the flow analysis module and to perform data acquisition, were developed using Quick BASIC4.5 as programming language. The analysis module for cobalt determination, employed solenoid mini-pumps for solutions pumping. The procedure was based on the cobalt catalytic effect on the Tiron oxidation by hydrogen peroxide and the photometric detection at 425 nm. After the necessary adjustments of the flow analysis module, the system showed good analytical performance. The following analytical characteristics for determination of cobalt in water were obtained: a relative standard deviation of 0.04% (n = 13) for a standard solution 0.5 &micro;gL-1 Co, a linear response ranging from 0.13 to 1.5 &micro;gL-1 Co (R = 0.998, n = 3), a detection limit of 0.06 &micro;gL-1, analytical frequency of 42 samples determination per hour and a waste generation of 1.5 mL per determination. Recoveries between 84 and 114% were obtained with the addition of Co (II) in water samples. The analytical module for determination of cadmium was developed, using two peristaltic mini-pumps and solenoid valves. The LED based photometer was furnished with a flow cell of long optical path (100 mm) and a LED with maximum emission at 520 nm. The flow analysis module was assembled with ability to perform a closed loop strategy, which was implemented to improve sensitivity. The analytical procedure for the determination of cadmium was based on reaction of Cd (II) with dithizone in a micelle medium with the surfactant Triton X-100. The procedure showed a linear response ranging from 15.0 to 175.0 &micro;gL-1 Cd (R = 0.997; n = 3), detection limit of 12.5 &micro;gL-1, RSD 0.57% (n = 10) for a sample of 30 &micro;gL-1 and analytical frequency of 43 samples per hour. Recoveries between 84 and 112% were obtained with addition of Cd (II) in water samples.

<p>Quasars form one of the most energetic phenomena in the universe, and can be traced out to very large redshifts. By studying the galaxies which host the active nuclei, important insights can be gained into the processes that trigger and maintain the quasar powerhouse. The evolution rate of the quasar population is furthermore similar to that of ordinary galaxies, which implies a connection between black hole accretion and star formation in the host galaxies. While the properties of quasar host galaxies at low redshift have become better constrained in recent years, less is known about hosts at earlier cosmic epochs. In addition, though radio-quiet quasars are by far more common than their radio-loud counterparts their host galaxies have not been studied to the same extent, in particular not at higher redshifts.</p><p>An imaging campaign of a large sample of quasars at intermediate redshift (0.4 < z < 0.8) was carried out at optical wavelengths using the Nordic Optical Telescope, and is studied in this thesis together with two smaller samples. The joint material forms more than half of the total number of observed sources in this redshift interval and increases the number of resolved radio-quiet hosts at z>0.4 considerably. The morphology and mean magnitudes are found to be similar for radio-loud and radio-quiet host galaxies. Both types of host are shown to have optical colours as blue as those of present-day late-type spirals and starburst galaxies, which is likely the result of ongoing star formation.</p><p>With increasing redshift, observations of host galaxies become more difficult. High spatial resolution can be achieved with adaptive optics, but the variation of the point spread function in the near-infrared wavelength band which is most suited for detection is large and rapid. A statistical approach to the problem of characterizing the point spread function has been developed, making use of simulated objects which are matched to the different atmospheric conditions. Bright, compact host galaxies showing signs of merging and interaction were detected in this way for three quasars at z~2.2, which were observed with the ESO 3.6 m telescope. The method is not restricted to host galaxy analysis but can be utilized in other applications as well, provided that the underlying extended source can be described by an analytical model. </p>

Quasars form one of the most energetic phenomena in the universe, and can be traced out to very large redshifts. By studying the galaxies which host the active nuclei, important insights can be gained into the processes that trigger and maintain the quasar powerhouse. The evolution rate of the quasar population is furthermore similar to that of ordinary galaxies, which implies a connection between black hole accretion and star formation in the host galaxies. While the properties of quasar host galaxies at low redshift have become better constrained in recent years, less is known about hosts at earlier cosmic epochs. In addition, though radio-quiet quasars are by far more common than their radio-loud counterparts their host galaxies have not been studied to the same extent, in particular not at higher redshifts. An imaging campaign of a large sample of quasars at intermediate redshift (0.4 &lt; z &lt; 0.8) was carried out at optical wavelengths using the Nordic Optical Telescope, and is studied in this thesis together with two smaller samples. The joint material forms more than half of the total number of observed sources in this redshift interval and increases the number of resolved radio-quiet hosts at z&gt;0.4 considerably. The morphology and mean magnitudes are found to be similar for radio-loud and radio-quiet host galaxies. Both types of host are shown to have optical colours as blue as those of present-day late-type spirals and starburst galaxies, which is likely the result of ongoing star formation. With increasing redshift, observations of host galaxies become more difficult. High spatial resolution can be achieved with adaptive optics, but the variation of the point spread function in the near-infrared wavelength band which is most suited for detection is large and rapid. A statistical approach to the problem of characterizing the point spread function has been developed, making use of simulated objects which are matched to the different atmospheric conditions. Bright, compact host galaxies showing signs of merging and interaction were detected in this way for three quasars at z~2.2, which were observed with the ESO 3.6 m telescope. The method is not restricted to host galaxy analysis but can be utilized in other applications as well, provided that the underlying extended source can be described by an analytical model.

El trabajo que presentamos en esta tesis tiene como finalidad la operación, calibración y análisis de datos ópticos del instrumento OMC (Optical Monitoring Camera) a bordo del satélite INTEGRAL (INTErnational Gamma-Ray Astrophysics Laboratory). La cámara OMC ofrece, por primera vez, la oportunidad de realizar observaciones fotométricas de larga duración en el rango óptico, simultáneamente con las de rayos X y rayos gamma. En la primera parte de la tesis describimos el proyecto INTEGRAL/OMC y sus operaciones científicas, detallando el proceso que hemos seguido para la construcción del catálogo de entrada de la OMC. Definimos la estrategia y requisitos que debe satisfacer el software de apuntado encargado de generar los telecomandos que controlan el funcionamiento de la cámara. La combinación del catálogo y el software de apuntado, junto con el buen funcionamiento del algoritmo de centrado de a bordo, han permitido la determinación del apuntado de la OMC, a bordo y en tiempo real, con una precisión mejor que 1 píxel desde el inicio mismo de las operaciones. La segunda parte se centra en el procedimiento que hemos elaborado para el análisis de los datos. Describimos el flujo de datos desde que llegan a tierra, pasando por los distintos sistemas de procesamiento, hasta que, finalmente, se convierten en datos científicos listos para ser utilizados por la comunidad astrofísica. Detallamos todos los aspectos relacionados con la calibración del instrumento. Explicamos los distintos algoritmos desarrollados para el análisis científico de los datos OMC, haciendo especial énfasis en las soluciones adoptadas para mejorar los resultados fotométricos y astrométricos del instrumento. En la última parte presentamos los archivos y catálogos resultantes de las observaciones realizadas con la cámara OMC. Describimos los archivos de datos procesados en tiempo real y de datos consolidados, así como el portal Web de acceso a los datos OMC. Avanzamos lo que será el catálogo final de la OMC, que contendrá todas las fuentes observadas y detectadas por este instrumento, una vez finalizada la misión INTEGRAL. Presentamos también dos de los subcatálogos preliminares obtenidos tras analizar determinados grupos de fuentes: "Contrapartidas ópticas de fuentes de altas energías del 4º Catálogo IBIS/ISGRI" y "Primer catálogo de fuentes variables observadas con la OMC". / The work presented in this thesis describes the system that allows the operation, calibration and data analysis of the OMC instrument (Optical Monitoring Camera) on board the ESA's INTEGRAL spacecraft (INTErnational Gamma-Ray Astrophysics Laboratory). The OMC camera offers, for the first time, the opportunity to perform long photometric observations in the optical range simultaneously to those in the X-ray and gamma-ray bands. In the first part of the thesis we describe the INTEGRAL/OMC project and its scientific operations, giving some details about the building process of the OMC Input Catalogue. We define the strategy and requirements of the OMC Pointing Software which generates the telecommands to control the camera operations. The combination of both the Input Catalogue and the Pointing Software, as well as the excellent behaviour of the on-board centring algorithm, allow us the on-board determination in real time of the OMC pointing direction with an accuracy better than 1 pixel from the beginning of the mission operations. The second part is focused on the development involved in the data analysis procedures. We describe the data flow starting when the telemetry data are received at Earth, followed by the different data processing stages present in the systems, until they are finally converted into scientific data which can be used by the astrophysics community. We explain all aspects related to the instrument calibration and the algorithms developed for the OMC scientific analysis, making special emphasis in the adopted solutions that allowed us to improve the photometric and astrometric results. In the last part we present the archives and catalogues compiled with the OMC data obtained during INTEGRAL observations. We describe the consolidated and near real time data archives as well as the OMC Archive Web Portal. We summarize the contents of the final OMC Catalogue which will be published at the end of the INTEGRAL mission including all sources observed and detected by OMC. In addition we present two preliminary sub-catalogues obtained by analysing some specific objects groups: "OMC optical monitoring of sources in the 4th IBIS/ISGRI catalogue" and "The first INTEGRAL/OMC Catalogue of optically variable sources".

The study of white dwarfs (WDs) provides insight into understanding WD formation rates, evolution, and space density. Individually, nearby WDs are excellent candidates for astrometric planetary searches because the astrometric signature is greater than for an identical, more distant WD system. As a population, a complete volume-limited sample is necessary to provide unbiased statistics; however, their intrinsic faintness has allowed some to escape detection. The aim of this dissertation is to identify nearby WDs, accurately characterize them, and target a subset of potentially interesting WDs for follow-up analyses. The most unambiguous method of identifying new WDs is by their proper motions. After evaluating all previous southern hemisphere proper motion catalogs and selecting viable candidates, we embarked on our own southern hemisphere proper motion survey, the SuperCOSMOS-RECONS (SCR) survey. A number of interesting objects were discovered during the survey, including the 24th nearest star system -- an M dwarf with a brown dwarf companion. After a series of spectroscopic observations, a total of 56 new WD systems was identified (18 from the SCR survey and 38 from other proper motion surveys). CCD photometry was obtained for most of the 56 new systems in an effort to model the physical parameters and obtain distance estimates via spectral energy distribution fitting. An independent distance estimate was also obtained by deriving a color-MV relation for several colors based on WDs with known distances. Any object whose distance estimate was within 25 pc was targeted for a trigonometric parallax via our parallax program, CTIOPI. Currently, there are 62 WD systems on CTIOPI. A subset of 53 systems has enough data for at least a preliminary parallax (24 are definitive). Of those 53 systems, nine are previously known WDs within 10 pc that we are monitoring for perturbations from unseen companions, and an additional 29 have distances within 25 pc. Previously, there were 109 known WDs with parallaxes placing them within 25 pc; therefore, our effort has already increased the nearby sample by 27%. In addition, at least two objects show hints of perturbations from unseen companions and need follow-up analyses.

Martian clouds and dust play an important part of the radiative transfer and energy balance budget. To assist in fully understanding the impact of clouds and dust, the complete diurnal cycle needs to be characterized. One of the best methods to track diurnal variations on Mars is by measuring optical depth. The spatial and temporal trends of optical depth give insight into the dust and water cycles of the Martian atmosphere. Until now, spacecraft could only obtain optical depth during the day. In this thesis, nighttime images from the Mars Exploration Rover Spirit are used to calculate nighttime optical depth using photometric methods to capture star flux. Bright stars in well-known constellations are used in this analysis. The observed flux was compared to the expected flux to give nighttime optical depth values. The observed nighttime optical depth was consistently similar to the daytime optical depth values on both an individual image and sol-averaged basis. Recommendations are made going forward to use the Mars Science Laboratory Curiosity for conducting an optimal nighttime optical depth campaign to fully characterize the diurnal dust and water cycles of Mars. The Curiosity rover is well suited for nighttime imaging and can potentially provide valuable insight into the nighttime dust and cloud trends.