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A method for determining percent cloud cover by taking two consecutive images using different color contrast filters, specifically a red filter and a blue filter, is described. This method (RF/BF estimate) involves dividing the "red" image by the "blue" image, pixel by pixel, and determining the percentage of pixels in the resultant image with intensity values of one. This is the percent cloud cover. The RF/BF estimate is based on the different effects of molecule and particle scattering of electromagnetic waves in the visible portion of the spectrum. These two types of scattering, Rayleigh and Mie scattering respectively, are described as they relate to this methodology. The RF/BF estimates are compared to visual estimates of percent cloud cover using the northern portion of 100 Central Florida skies collected during the period from January 28, 1988 to February 25, 1988. A strong correlation r=0.94 was found between the RF/BF and visual estimates. Advantages of the method are discussed along with implications and suggestions for follow-up studies.

The following conclusions may be drawn from this investigation: (1) The photometer is an accurate and dependable device for measuring light absorption by turbid soil and water solutions when the soil particles are of nearly constant size. The tests made with the soil that had passed through a 100-mess sieve proved this fact, also, the tests made with the composite soil gave vary accurate results. (2) the composite runoff soil samples from the three slopes must have contained particles of approximately the same size. This is shown by the accuracy of the results obtained with this soil. / Master of Science

The objectives of this research were to evaluate non-invasive measures of bone mineral content (BMC) and bone mineral density (BMD) as rapid, on-farm tools to assess phosphorus (P) status in dairy cows. In addition, the effects of parity and stage of lactation on measures of BMC of the fused 3rd and 4th metacarpal bone and of caudal vertebrae 14 and 15 were assessed. The caudal vertebrae and right front metacarpal (sample pairs) were excised from 107 Holstein cull cows following slaughter. Parity, age, and days in milk (DIM) of the donor animal were obtained for 43 pairs of samples. Samples were grouped by parity (1, 2, 3, and >4) and stage of lactation (Stage 1 = < 90 DIM, Stage 2 = > 90 and < 150 DIM, Stage 3 = >150 and < 250 DIM and Stage 4 = > 250 DIM). Samples were analyzed for BMC and BMD with dual energy X-ray absorptiometry (DXA), BMC with radiographic photometry (RP), breaking strength with mechanical methods, and mineral content with chemical procedures. Estimates of BMC obtained with RP and DXA were poorly related to chemical measures of actual BMC and to measures of breaking strength. In caudal vertebrae 14 and 15, increasing stage of lactation decreased energy to peak load with the lowest values observed in late lactation. Stage of lactation had no effect on BMC measured chemically in the caudal vertebrae or metacarpal. Parity did not affect breaking strength of the metacarpal or caudal vertebrae or total ash or P content of any bone. Results indicated that imaging techniques are not useful measures of BMC in mature dairy cattle. / Master of Science

Over recent years there has been an increase of the number of secure supermassive black hole (SMBH) detections. These SMBH measurements have lead astronomers to establish well defined empirical relationships between the SMBH mass and some of the properties of the host galaxy. The number of galaxies with SMBH mass measurements is currently limited to about 100. One approach of expanding the study of the SMBH is to use the empirical relations for estimating M[subscript(bh)] for larger samples of galaxies. The investigation of the SMBH population (or SMBH mass function) for large sample of galaxies in the nearby universe has helped to constrain the SMBH and the galaxy evolution. Previous estimates of the SMBH mass function at low redshift were produced mainly by combining the measurements of the galaxy luminosity or velocity function with one of the SMBH scaling relations. In the first part of the thesis I will present an independent construction of the nearby supermassive black hole mass function by applying the optical M[subscript(bh)]–L relation onto the Millennium Galaxy Catalogue (MGC). Additionally, in the second part I will provide photometric analysis of all UKIDSS galaxies for which SMBH masses have been measured. I will derive composite profiles of brightness, ellipticity and position angles of each galaxy. I will show that the Sérsic function fits the brightness profile of the majority of the elliptical galaxies and the bulge of disk galaxies and I will provide alternative multi-component fits when necessary. Then these photometric parameters will be used for constructing the M[subscript(bh)]–L relation in the near-IR and to investigate the M[subscript(bh)]–n relation. In the third part I will construct the near-IR SMBH mass function for the Galaxy and Mass Assembly (GAMA) survey. For this purpose I will apply the newly derived M[subscript(bh)]–L relation onto an elliptical subsample of K-band images. The advantage of this SMBH mass function is that during the M[subscript(bh)]–L construction I used the same quality images and techniques used on the GAMA survey. Apart from the M[subscript(bh)]–L relation, the M[subscript(bh)]–sigma relation was used as an alternative approach for a subsample of galaxies for which the velocity dispersions were available. Furthermore, I employed both local SMBH mass functions (MGC & GAMA) for estimating the SMBH mass density at redshift zero and accounted for the dependence of the total SMBH density on the look-back time by comparing with semi-analytic SMBH mass functions. Finally, from the SMBH mass density I estimated the baryon fraction that is locked into SMBHs.

Depuis leur formation, les surfaces des corps de notre Système Solaire montrent une diversité étonnante. Cette diversité est le reflet des processus géologiques qui ont modelé les surfaces planétaires au cours du temps. Parmi les objets du Système Solaire, Mars constitue un objet particulièrement intéressant car il présente de nombreuses similitudes avec notre planète. La minéralogie de la surface de Mars est bien documentée. Cependant, on dispose de peu d'information sur les paramètres physiques des matériaux qui sont également des traceurs des processus géologiques. Un des objectifs de cette thèse est de développer et de valider un outil permettant leur détermination à partir de techniques d'investigation spatiale depuis l'orbite et d’interpréter les résultats. Pour cela, une approche basée sur la photométrie, qui étudie les propriétés de diffusion des matériaux de surface, a été développée et validée. Ces propriétés de diffusion dépendent de la composition mais aussi des propriétés physiques des matériaux comme la taille, la forme, la structure interne, la rugosité des grains et la rugosité de la surface. Les données hyperspectrales multi-angulaires CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) à bord de la sonde Mars Reconnaissance Orbiter (11 images prises à des angles d'émergence variés) ont été utilisées, permettant de contraindre le comportement de diffusion des matériaux de surface. Tout d'abord, les données sont corrigées de la contribution atmosphérique à l'aide de l'algorithme nommée MARS-ReCO (Multi-angle Approach for Retrieval of Surface Reflectance for CRISM Observations), développé en collaboration avec Xavier Ceamanos et Sylvain Douté (IPAG) au cours de la thèse. Puis, les données de réflectance de surface à différentes géométries sont analysées en inversant à l’aide d’une approche bayésienne le modèle photométrique de Hapke qui décrit le transfert radiatif en milieu granulaire. Ce modèle dépend de six paramètres photométriques de surface (e.g., albédo de diffusion, fonction de phase, rugosité macroscopique de la surface), reliés aux propriétés physiques des matériaux comme la taille, la structure interne, la forme, la rugosité des grains, et la rugosité de la surface.Une première application a été menée au niveau des sites d'atterrissage des rovers de la mission Mars Exploration Rover, où des données orbitales et in situ sont disponibles. Ces dernières sont utilisées comme «vérité terrain» pour valider les interprétations des paramètres photométriques estimés. Dans ce travail, des cartes des paramètres photométriques ont été fournies le long et autour du trajet des rovers permettant d'avoir accès aux informations des propriétés des matériaux sur une étendue plus importante que les données in situ. Une interprétation de chacun des paramètres et un lien aux propriétés physiques et aux processus géologiques ont été fournis. Les résultats montrent des propriétés de diffusion variés au sein d'une observation CRISM (10x10km) suggérant que les surfaces sont contrôlées par des processus géologiques plus locaux (e.g., processus éoliens, fragmentation de la croûte par impact).Une dernière partie se focalise sur la détermination des propriétés de diffusion des matériaux de surface de différents terrains géologiques formés dans des contextes différents. Le but est d'identifier les variabilités des propriétés de diffusion à travers Mars / The PhD work focuses on the characterization of geological processes on planetary surfaces. Due to the lack of broad scale in situ information about the surface physical properties of the Martian materials (recording the geological processes), my work centers on the development and validation of an approach for their estimation from orbital spaceborne datasets. In addition, determining the physical properties has an implication for the spectroscopic interpretation notably for the mineral abundances. More specifically, I developed an approach for the determination and the analysis of the Martian surface scattering properties using CRISM (Compact Reconnaissance Imaging Spectrometer for Mars) observations [Murchie et al., 2007] on-board MRO (Mars Reconnaissance Orbiter). CRISM provides multi-angular (varied emission angles) hyperspectral images which allow the characterization of the surface scattering behavior at ∼200m/pixel. The scattering behavior depends on the material composition but also the physical properties such as the grain size, shape, internal structure, and the surface roughness / porosity. The main objective is to observe the spatial variations of the surface scattering properties and the photometric parameters as a function of geological units.The methodology I employ is based on the estimation of the surface photometric parameters in term of surface physical properties. After an atmospheric correction (aerosols) by the Multi-angle Approach for Retrieval of the Surface Reflectance from CRISM Observations (MARS-ReCO) [Ceamanos et al., 2013] developed in collaboration with X. Ceamanos and S. Douté (IPAG, France), I analyze the surface reflectance taken at varied geometries by inverting the Hapke photometric model [Hapke, 1993] depending on six parameters (single scattering albedo, 2-term phase function, macroscopic roughness and 2-term opposition effects parameters) in a Bayesian framework [Fernando et al., 2013]. The algorithm for the correction for the aerosols and the methodology for the estimates of surface photometric parameters have been validated by comparing the results from orbit to the in situ photometric measurements from Mars Exploration Rover (MER) rovers [Fernando et al. 2013].The MER landing sites located at Gusev Crater and Meridiani Planum provide an excellent opportunity to ground truth and validate the interpretation of derived Hapke photometric parameters as both orbital and in situ data are readily available over numerous geological terrains. Orbital results are consistent with the in situ observations. In my work, I mapped the surface scattering properties in and around the rover path, providing extended information over a wider area. Significant variations in the scattering properties are observed inside a CRISM observation (10x10km) suggesting that the surfaces are controlled by local geological and climatic processes [Fernando et al., in revision].The last part of this work focuses on the determination of the surface photometric parameters of different Martian geological terrains under different contexts in order to identify variabilities of the scattering properties

In this study we present photometric predictions for C-type Asymptotic Giant Branch Stars (AGB) stars from Eriksson et al. (2014) for the James Webb Space Telescope (JWST) and the Wide-field Infrared Survey Explorer (WISE) instruments. The photometric predictions we have done are for JWST’s general purpose wide-band filters on NIRCam and MIRI covering wavelengths of 0.7 — 21 microns. AGB stars contribute substantially to the integrated light of intermediate-age stellar popula- tions and is a substantial source of the metals (especially carbon) in galaxies. Studies of AGB stars are (among other reasons) important for the understanding of the chemical evolution and dust cycle of galaxies. Since the JWST is scheduled for launch in 2018 it should be a high priority to prepare observing strategies. With these predictions we hope it will be possible to optimize observing strategies of AGB stars and maximize the science return of JWST. By testing our method on Whitelock et al. (2006) objects from the WISE catalog and comparing them with our photometric results based on Eriksson et al. (2014) we have been able to fit 20 objects with models. The photometric data set can be accessed at: http://www.astro.uu.se/AGBmodels/ / I den här studien har jag gjort fotometriska förutsägelser för asymptotis- ka jättegrensstjärnor (AGB-stjärnor) av C typ från Eriksson et al. (2014) modifierade för instrument ombord på James Webb Space Telescope (JWST) och Wide-field Infrared Survey Explorer (WISE). AGB-stjärnor bidrar kraftigt till det totala ljuset av stjärnor av intermediär ålder och är också en stor källa till metaller (speciellt kol) i galaxer. Studier av AGB stjärnor är viktiga av flera anledningar, däribland för att förstå den kemiska evolutionen och stoftcykler i galaxer. JWST är planerad att skjutas upp 2018 och fram till dess bör det vara en hög prioritet att förbereda observeringsstrategier. Med den fotometriska datan i den här studien hoppas vi att användare av JWST kommer kunna optimera sina observeringsstrategier av AGB-stjärnor och få ut så mycket som möjligt av sin obseravtionstid med teleskopet. Vi har testat metoden genom att titta på objekt från Whitelock et al. (2006) i WISE-katalogen och jämföra dem med de fotometriska resultaten baserade på modellerna från Eriksson et al. (2014). På detta sett har vi lyckats matcha 20 objekt med modeller. Den fotometriska datan går att ladda ner ifrån: http://www.astro.uu.se/AGBmodels/

We present deep imaging of the most distant dwarf discovered by the Dark Energy Survey, Eridanus II (Eri II). Our Magellan/ Megacam stellar photometry reaches similar to 3 mag deeper than previous work and allows us to confirm the presence of a stellar cluster whose position is consistent with Eri II's center. This makes Eri II, at M-V = -7.1, the least luminous galaxy known to host a (possibly central) cluster. The cluster is partially resolved, and at MV = -3.5 it accounts for similar to 4% of Eri II's luminosity. We derive updated structural parameters for Eri II, which has a half-light radius of similar to 280 pc and is elongated (epsilon similar to 0.48) at a measured distance of D similar to 370 kpc. The color-magnitude diagram displays a blue, extended horizontal branch, as well as a less populated red horizontal branch. A central concentration of stars brighter than the old main-sequence turnoff hints at a possible intermediate-age (similar to 3 Gyr) population; alternatively, these sources could be blue straggler stars. A deep Green Bank Telescope observation of Eri II reveals no associated atomic gas.

Cosmological constraints from galaxy clusters rely on accurate measurements of the mass and internal structure of clusters. An important source of systematic uncertainty in cluster mass and structure measurements is the secure selection of background galaxies that are gravitationally lensed by clusters. This issue has been shown to be particular severe for faint blue galaxies. We therefore explore the selection of faint blue background galaxies, by reference to photometric redshift catalogues derived from the Cosmological Evolution Survey (COSMOS) and our own observations of massive galaxy clusters at z similar or equal to 0.2. We show that methods relying on photometric redshifts of galaxies in/behind clusters based on observations through five filters, and on deep 30-band COSMOS photometric redshifts are both inadequate to identify safely faint blue background galaxies with the same 1 per cent contamination level that we have achieved with red galaxies. This is due to the small number of filters used by the former, and absence of massive galaxy clusters at redshifts of interest in the latter. Nevertheless, our least contaminated blue galaxy sample yields stacked weak-lensing results consistent with our previously published results based on red galaxies, and we show that the stacked clustercentric number density profile of these faint blue galaxies is consistent with expectations from consideration of the lens magnification signal of the clusters. Indeed, the observed number density of blue background galaxies changes by similar to 10-30 per cent across the radial range over which other surveys assume it to be flat.

Dans cette thèse a été développé un modèle numérique simulant la lumière réfléchie et l'émission thermique d'exoplanètes telluriques ne possédant pas d'atmosphère, au cours de leur orbite. Ce modèle est constituée de plusieurs éléments. Le code calcule tout d'abord le flux stellaire incident en tout point de la planète et en fonction du temps en prenant en compte le mouvement orbital et la rotation de la planète. Si nécessaire, le modèle peut calculer la dissipation associée aux forces de marées et le flux de chaleur interne associé. Ces flux radiatif et interne servent de conditions aux limites à un modèle qui traite la diffusion de la chaleur dans la subsurface et calcule la température de surface. Enfin, le code calcule le flux, et sa variation avec la phase orbitale, reçu par un observateur distant dans une ou plusieurs bandes spectrales. Ce flux peut inclure les sources de bruits associés à la méthode d'observation de façon à produire une observable réaliste.Une première étude a été consacrée aux planètes en orbite circulaire et en rotation synchrone, c'est à dire recevant un flux d'illumination constant avec le temps. Cette étude a montré qu'il était possible de contraindre, à partir d'observations bruitées simulées effectuées avec les télescopes de la prochaine génération (JWST, EChO) leur albédo de Bond, leur rayon, et l'inclinaison de l'orbite par rapport à l'observateur. Associée à des mesures de vitesse radiale, cette technique pourra permettre de déterminer masse et rayon d'exoplanètes ne transitant pas.Une seconde étude traite de l'influence de la rotation et de la force maréale pour des planètes recevant un flux d'illumination non constant (excentriques et/ou en rotation). Il est montré qu'il est possible de détecter par photométrie orbitale la signature de ces deux effets dans la courbe de lumière et ainsi de mieux contraindre les modèles de marées existants. De multiples possibilités d'applications de ce modèle numérique sont en cours, et se prolongent au-delà de cette thèse. / We have developed a numerical model that computes the reflected light and thermal emission of an airless rocky exoplanets during its orbit. This code first computes the stellar incident flux over the planetary surface as a function of time for any Keplerian orbit and rotation. The code can compute the tidal dissipation and the associated internal heat flux. Those illumination and internal flux are the boundary conditions for a heat diffusion model, which calculates time-dependent surface and subsurface temperatures. Eventually, the model computes the flux received by a distant observer, in one or several spectral bands. A realistic observation can be simulated adding the various sources of noise noise associated with the observation method.A first study was dedicated to synchronous planets on a circular orbit that receive a constant illumination flux. This study showed that it is possible to constrain their Bond albedo, radius and inclination from observations done with the JWST or EChO. Associated with radial velocity measurements, mass and radius of nontransiting planets can be inferred. In another work on planets receiving a non constant illumination flux (eccentric orbits or non synchronous planets) we study the signature of rotation period the tidal dissipation in the orbital photometry. We show that rotation period can be inferred providing a novel method to test tidal models. Many possibles applications of this model are already in progress and continue to be developed beyond this thesis.