Study of the time variable sources and phenomena in Astrophysics provides us with important insights into the stellar evolution, galactic evolution, stellar population studies and cosmological studies such as number density of dark massive objects. Study of these sources and phenomena forms the basis of Time Domain surveys, where the telescopes while scanning the sky regularly for a period of time provides us with positional and temporal data of various Astrophysical sources and phenomena happening in the Universe. Our vantage point within the Milky Way galaxy greatly limits studying our galaxy in its entirety. In such a scenario our nearest neighbour The Andromeda galaxy (M31) proves to be an excellent choice as its proximity and inclination allows us to resolve millions of stars using space based telescopes. Zwicky Transient Facility (ZTF) is a new optical time domain survey at Palomar Observatory, which has collected data in the direction of M31 for over 6 months using multiple filters. This Thesis involves exploitation of this rich data set. Stars in M31 are not resolved in ZTF as it is a ground based facility. This requires us to use the large public catalogue of stars observed with Hubble Space Telescope (HST): The Panchromatic Hubble Andromeda Treasury (PHAT). The PHAT catalogue provides us with stellar coordinates and observed brightness for millions of resolved stars in the direction of the M31 in multiple filters. Processing of the large volumes of data generated by the time domain surveys, requires us to develop new data processing pipelines and utilize statistical techniques for determining various statistical features of the data and using machine learning algorithms to classify the data into different categories. End result of such processing of the data is the astronomical catalogues of various astrophysical sources and phenomena and their light curves. In this thesis we have developed a data processing and analysis pipeline based on Forced Aperture Photometry Technique. Since the stars are not resolved in ZTF, we performed photometry at pixel level. Only small portion of the ZTF dataset has been analyzed and photometric light curves have been generated for few interesting sources. In our preliminary investigations we have used a Machine Learning Algorithm to classify the resulting time series data into different categories. We also performed cross comparison with data from other studies in the region of the Andromeda galaxy.

The thesis deals with the pouring of epoxy materials over LED strips. The research part contains an introduction to photometry and summarizes the types of potting compounds along with their characteristics. The practical part delves into the effect different amount of pigment has on the photometric properties. This is assessed based on verified measurements performed with the help of a goniophotometer on samples with different amounts of pigment, which were created using an integration sphere. Furthermore, a brightness analysis and a long-term outdoor test were performed.

The master’s thesis deals with photometry units used in light engineering. There are defined the methods of modelling the illumination systems, their advantages, disadvantages and possibilities of using. Furthermore, the thesis deals with modelling of two illumination systems by ray-tracing in programming environment of MATLAB. The master’s thesis describes the analysis of the problem and the program designing process. Acquired model results are then compared with the real measurements of both illumination systems which allow the discussion of the results and the deviations of the models.

This thesis is focused on the theoretical and practical introduction to the verification procedures used today for obtaining luminosity curves of lamps. The introduction acquaints readers with the photometric variables. Consequently, it is theoretically described procedure for constructing luminance curves by zonal flow and further familiarization with the near-field photometry. For the practical part was chosen several lights. These lamps were measured by luxmeter first from a very close photometric distance from lights, and then from large distance. The next step was to obtain pictures of luminaries in planes C 0 to 345 ° (with a step of 15 °) of the angle gamma from 0 to 180 ° (in steps of 5 °). The measured data were processed by zonal flow and through programs LumiDISP and Matlab. The partial result of this thesis is to verify whether it is possible to use the luminance analyzer for obtaining luminosity curves, it means, if the luminosity curve obtained through luminance analyzer will comply with the curves obtained through a luxmeter. Further work should ascertain the feasibility of acquired photographs lamps from a very close photometric distance could create luminosity curve for any location and distance from the observer to measured lamps.

This master's thesis is focused on problematic of measurent unceartainties in photometry. Theoretical part describes photometric measururing instruments, their uncearnities and limitations. In the second part of this thesis there is a mathematical description of calculating uncearnities in laboratory conditions. In practical part there are calculations of uncearnities for photometric instruments at light laboraty VUT Brno.

This thesis is focused on measuring the quality of lighting in operating rooms. Operating lights are very demanding in terms of quality requirements for each parameter, so it is important to specify exactly these parameters and check them regurarly. To measure the quality of the light source, was used a special kit from Maquet. Measurement procedure was not as accurate as it was for operating lighting need, therefore, this work includes a proposal to improve the measurement of quality lighting in operating theaters. In cooperation with University Hospital Brno Bohunice University Hospital Motol and the company Maquet measured nine operating lights, each light were compared in terms of parameters such as maximum light intensity, light distribution in the surgical field. In each category were selected several lighting, which reached the best results. The various parameters were compared with values declared by the manufacturer.

In this thesis, we present the Monte Carlo study of two prototypes of tele- scopes for the Cherenkov Telescope Array (CTA) observatory, followed by the first data analysis partially using our reconstruction pipeline based on Random Forests. The Monte Carlo model of the SST-1M prototype is created and val- idated by comparison with data. Using the precise Monte Carlo models, we evaluate the performance of the SST-1M and LST-1 prototypes, working so-far in mono-regime as standalone telescopes, resulting in their energy and angular resolution, and the differential sensitivity. We also present an analysis of the data from the first two Crab Nebula observation campaigns conducted with the LST-1 telescope. In the last part of the thesis, we present a study of aerosol optical depth of the atmosphere above both future sites of the CTA observa- tory, retrieved from photometric measurements of Sun/Moon photometers. We focus on the photometer in-situ calibration for nocturnal measurements and introduce corrections to minimize systematic shifts between diurnal and noc- turnal measurements. Using the developed methods, we present the aerosol characterization of both CTA sites based on the photometric data. 1

Les satellites glacés de Jupiter sont d'un grand intérêt scientifique dans la recherche d'habitabilité au sein de notre système solaire. Elles abritent probablement toutes trois des océans d'eau liquide sous leur croûte glacée. Leurs surfaces présentent différents stades d’évolution – celle de Callisto est très ancienne et entièrement recouverte de cratères, celle de Ganymede est un mélange de terrains sombres et cratérisés et de plaines claires et plus jeunes et la surface d’Europa est la plus jeune et présente des signes d’activité récente. Cette thèse porte sur la photométrie, c’est à dire l’étude de l’énergie lumineuse réfléchie par une surface, en fonction des géométries d’éclairement et d’observation. Les études photométriques permettent de déterminer l’état physique et la microtexture des surfaces (porosité, structure interne, forme des grains, rugosité, transparence…). Une bonne connaissance photométrique est également d'une importance cruciale dans la correction des jeux de données pour toute étude cartographique ou spectroscopique ainsi que pour les futures missions de cette décennie : Europa Clipper de la NASA et JUpiter ICy Moons Explorer de l’ESA.Deux types d’information sont nécessaires pour réaliser une étude photométrique : des données de réflectance et des données géométriques (conditions d’illumination et d'observation). Pour obtenir les premières, nous avons utilisé et calibré des images de missions spatiales passées - Voyager, New Horizons et Galileo. Pour obtenir les secondes, nous avons développé des outils permettant de corriger les métadonnées de ces images (ex : la position et l'orientation des sondes) afin d’obtenir des informations géométriques précises. Nous avons, d’autre part, développé un outil d’inversion pour estimer les paramètres photométriques de Hapke sur des régions d’Europa, Ganymede et Callisto sur l’ensemble du jeu de données en un seul calcul. Enfin, nous discutons des liens possibles entre les paramètres photométriques estimés, la microtexture de la surface et les processus endogènes/exogènes mis en jeu. / Jupiter's icy moons are of great interest in the search for habitability in our Solar System. They probably all harbor liquid water ocean underneath their icy crust. Their surfaces present different stages of evolution – Callisto is heavily cratered and the oldest, Ganymede shows a combination of dark cratered terrain and younger bright plains and Europa’s surface is the youngest with signs of recent and maybe current activity. This work focuses on photometry, i.e. the study of the light scattered by a surface in relation to the illumination and observation geometry. Photometric studies give us insight on the physical state and microtexture of the surface (compaction, internal structure, shape, roughness, transparency…). A good photometric knowledge is also of crucial importance in the correction of datasets for any mapping or spectroscopic study as well as for the future missions of this decade – NASA’s Europa Clipper and ESA’s JUpiter ICy moons Explorer.Two pieces of information are necessary to conduct a photometric study – reflectance data and geometric information (illumination, viewing conditions). For the former, we have used and calibrated images from past space missions – Voyager, New Horizons and Galileo. For the latter, we have developed tools to correct these images metadata (e.g. spacecraft position and orientation) to derive precise geometric information. Moreover, we have developed a Bayesian inversion tool to estimate Hapke’s photometric parameters on regions of Europa, Ganymede and Callisto. We estimate all parameters on our entire dataset at once. Finally, we discuss the possible links between the photometric parameters, the surface microtexture and endogenic/exogenic processes.

Galaxy clusters are the largest gravitationally bound structures in the Universe. Their masses are dominated by dark matter ($\sim$85\% of the mass) with stars representing 1-4\% of their masses. A hot, X-ray emitting gas called the intracluster medium makes most of their baryonic mass. The presence of this gas and of numerous neighbouring galaxies prematurely stop the star formation in clusters. In other terms, more galaxies in clusters are passive than in the general population of galaxies. This effect is mass and position-dependant: high-mass galaxies are more likely to be passive than less massive ones; galaxies inhabiting the cluster core are also less likely to form stars than those in the outskirts. The fraction of passive galaxies is greater in local clusters than in high-redshift ones, because they had more time to evolve. Much is unknown about the cessation of star formation, called quenching, in clusters. Thus, although many examples of infalling galaxies being stripped of their gas have been reported for low-mass galaxies, it is unclear if the most massive members became quenched before or after they become cluster members. The relationship between quenching and the cluster mass is also poorly understood. Despite the variety of methods devised to find clusters of galaxies, most of what we know about quenching in $z\gtrsim 1$ clusters was discovered with optically/infrared-selected cluster samples (clusters found as overdensities of galaxies), or samples of mixed origin. Yet, there is tentative evidence that optically/infrared-selected samples are biased toward having more passive galaxies than those that were X-ray selected. In the present dissertation, quenching is explored in X-ray selected cluster samples. A sample of high-redshift, low-mass galaxy clusters is built by finding galaxy overdensities coincident with sources of extended X-ray emission. A photometry-based analysis reveals that the fraction of quenched galaxies in these clusters is very variable. Moreover, the brightest cluster galaxies are also diverse. Yet, for all the information that photometry can provide, this sample candidate clusters need to be confirmed with spectroscopy. Spectroscopic observations obtained for four candidate clusters are reduced and analysed. The results show that three of them are clusters, the fourth candidate being a superposition of structures. Member spectra are examined to infer their star formation history, and the results shows the existence of an intermediary population of galaxies, where an old stellar population coexists with weak star formation. Finally, the galaxies of a $z=1.98$ X-ray selected cluster, XLSSC 122 are investigated in detail. Photometric data in 12 bands are organized to perform spectral energy distribution fittings, a technique that allows a simplified reconstitution of the history of the star formation. Results show that the members were formed at diverse epochs, the oldest being about 2.5 Gyrs old. Simulations drawn from the Multi Dark Planck 2 are used to infer the mass-scale of the cluster when the oldest galaxies were formed, something that has never been done before. The oldest galaxies were probably formed when XLSSC 122 had accreted $<$10\% of its $z=1.98$ mass, i.e. the mass-scale of a galaxy group. / Graduate

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