We derive the stellar mass fraction in the galaxy cluster RXC J2248.7-4431 observed with the Dark Energy Survey (DES) during the Science Verification period. We compare the stellar mass results from DES (five filters) with those from the Hubble Space Telescope Cluster Lensing And Supernova Survey (CLASH; 17 filters). When the cluster spectroscopic redshift is assumed, we show that stellar masses from DES can be estimated within 25 per cent of CLASH values. We compute the stellar mass contribution coming from red and blue galaxies, and study the relation between stellar mass and the underlying dark matter using weak lensing studies with DES and CLASH. An analysis of the radial profiles of the DES total and stellar mass yields a stellar-to-total fraction of f(star) = (6.8 +/- 1.7) x 10(-3) within a radius of r(200c) similar or equal to 2 Mpc. Our analysis also includes a comparison of photometric redshifts and star/galaxy separation efficiency for both data sets. We conclude that space-based small field imaging can be used to calibrate the galaxy properties in DES for the much wider field of view. The technique developed to derive the stellar mass fraction in galaxy clusters can be applied to the similar to 100 000 clusters that will be observed within this survey and yield important information about galaxy evolution.

Thesis. 1977. Ph.D.--Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING. / Bibliography : p. 185-189. / by Robert J. Woodham. / Ph.D.

This thesis demonstrates that any individual can provide relevant observational data to further research efforts within the Aerospace community, through the use of amateur telescopes. A Meade LX200 12 in. telescope and Lumenera Skynyx 2.0 camera were utilized to observe small LEO satellites, using a well-documented point-and-wait staring method. Over a period of three months, a total of 186 observation attempts were made resulting in 97 successful captures. From the gathered data, three possible aerospace applications were analyzed: validation of a satellite brightness prediction model, angles-only orbit determination including extended Kalman filtering, and temporal error growth in TLE-based orbit propagation. Further investigations include a preliminary optimization using MATLAB's fmincon function (informed by the previous analyses) to determine an optimal telescope size for performing LEO observations.

The Citizen Continental-America Telescopic Eclipse (CATE) Experiment established a standardized set of observation procedures and 72 volunteer observation teams with identical equipment along the path of the 2017 total solar eclipse. CATE successfully imaged the solar corona from 66 of the 72 observation sites resulting in a high dynamic range animation of 90 minutes of solar corona data collected by volunteer citizen science teams. A subgroup of CATE began work in the fall of 2017 to evaluate use of the standard CATE observation setup for exoplanet transit observations. Light curves and analysis of data using AstroImageJ of two well know transiting exoplanets, HD209458b (V = 7.65, depth = 1.5%) and HD189733b (V= 7.67, depth=2.4%) are presented along with modifications to CATE telescopes required for successful exoplanet follow up observations.

The thesis' primary function was the period determination of k Bootis, and S Scuti Variable, through long time-base UBV photoelectric photometry. Data was analyzed using Barning's method, a Fourier technique in searching for the primary and beat periods within the range 0.0486 to 0.0826 days and 13 to 19 days respectively. The study's secondary function was the identification of overtones and the acquisition of any other information concerning this star.Ambiguity resulting from the period determinations of Millis (1966) and Desikachary et al. (1971) was tentatively resolved; the most accurate determination from this investigation gives a period of 0.07361 days and a (m of 0.05 magnitude. A beat period of 13.32 days with a o m of 0.088 magnitude was found which widely differs from the 16-day beat suggested by the Desikachary group. Due to noise problems, secondary frequencies could not be soundly identified, though the Fourier "spectra" indicated their existence. However, this study when combined with that of Desikachary et al. supports the hypothesis that K Bootis might have an undiscovered very close companion in addition to its "wide" binary component. This close binary nature may be typical of one type of δ Scuti variable.Ball State UniversityMuncie, IN 47306

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Exoplanets that transit nearby M dwarfs allow us to measure the sizes, masses, and atmospheric properties of distant worlds. Between 2008 and 2013, we searched for such planets with the MEarth Project, a photometric survey of the closest and smallest main-sequence stars. This thesis uses the first planet discovered with MEarth, the warm 2.7 Earth radius exoplanet GJ1214b, to explore the possibilities that planets transiting M dwarfs provide. / Astronomy

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Στόχος της παρούσης εργασίας είναι η διερεύνηση των μεταβολών της ροής της οπτικής ακτινοβολίας στα φίλτρα B, V, R στη διάρκεια μιας νύχτας του ενεργού γαλαξία S5 1803 + 784 με ανάλυση παρατηρήσεων που ελήφθησαν με το τηλεσκόπιο των1.3m του αστεροσκοπείου του Πανεπιστημίου Κρήτης (από τον Δρ. Παν. Μπούμη) με τη μέθοδο της συγκριτικής φωτομετρίας. Στο πρώτο κεφάλαιο περιγράφονται τα γενικά χαρακτηριστικά των κανονικών γαλαξιών και του δικού μας γαλαξία, ενώ στο δεύτερο τα γενικά χαρακτηριστικά των ενεργών γαλαξιών ή ενεργών γαλαξιακών πυρήνων (AGN) - επειδή τα έντονα ενεργητικά φαινόμενα επικεντρώνονται στην κεντρική περιοχή του πυρήνα. Αναφέρεται η διάκρισή τους σε κατηγορίες με βάση τα παρατηρησιακά χαρακτηριστικά και εξετάζονται οι βασικές ιδέες που οδηγούν στο επικρατέστερο μοντέλο ενοποίησης, σχετικά με την ενεργειακή μηχανή τους καθώς και η εξέλιξη και τροποποίηση του με βάση τα νέα πειραματικά δεδομένα. Το τρίτο κεφάλαιο επικεντρώνεται στα ιδιαίτερα χαρακτηριστικά των blazars στα οποία ανήκει ο S5 1803 + 784. Στο τέταρτο κεφάλαιο περιγράφονται συνοπτικά οι βασικές αρχές της φωτομετρίας αλλά και οι βασικές παράμετροι μιας CCD κάμερας. Στο τέταρτο κεφάλαιο γίνεται μια βιβλιογραφική παρουσίαση του S5 1803 +784 σε όλα τα μέρη του φάσματος και περιγράφονται αναλυτικά οι παρατηρήσεις, τα αρχικά στάδια επεξεργασίας των αστρονομικών εικόνων και τα αναλυτικά στάδια της φωτομετρίας του γαλαξία με τις απαραίτητες διορθώσεις. Τέλος στο έκτο κεφάλαιο κατασκευάζονται οι καμπύλες μεταβολής της ροής και σχολιάζονται τα αποτελέσματα Ακολουθεί στο παράρτημα, η περιγραφή των προγραμμάτων και των διαδικασιών που χρησιμοποιήθηκαν τόσο στην ανάλυση όσο και στην φωτομετρία μέσω των αστρονομικών πακέτων IRAF και MIDAS , ως μικρός οδηγός για τους επόμενους ενδιαφερόμενους. / The main aim of this dissertation entitled “Variabillity in the optical band of blazar S51803+784” is the investigation of flux microvariability through observations carried out with the 1.3 m , Ritchey-Chretien telescope at Skinakas Observatory in Crete, Greece (by Associate Researcher P. Boomis of the Institute of Astronomy and Astrophysics of the National Observatory in Athens) in 2001 under the supervision of Lecturer Mrs E-P. Christopoulou (Physics Dept. University of Patras, Greece). This work consists of six relatively distinct chapters. The first chapter summarizes the main characteristics of normal galaxies whereas the second one describes the various classes of Active Galactic Nuclei which emerge from multiwavelength studies and the unified model proposed to explain the energy source behind their taxonomy. The last section of this part focuses on the observational evidence of supermassive black holes. The third chapter focuses on the special characteristics of the class named Blazars, the proposed theoretical models for the formation of jets and the observed microvariability thought the EM spectrum. The fourth chapter describes the main philosophy of photometry, the comparison of differential and absolute photometry and the selection of photometric standard stars. The last part briefly presents the charge-coupled devices (CCDs) which are used to record astronomical images and their main properties. The fifth chapter deals with the current observations of the Blazar S51803+784 and the standard image processing (bias substraction and flat fielding using twilight –sky exposures) applied to all frames before the performance of aperture photometry techniques which is described analytically in the rest part. The topics covered include methods for image center determination, routines for estimating the sky background and the techniques of both aperture and point-spread function fitting photometry. Procedures for transforming instrumental magnitudes to those on a standard system are also discussed. The results based on the data reduction of the photometric observations of the object are presented in the last chapter together with the discussion and conclusions. Finally in the Appendix there is a mini-guide for the beginner in order to be familiar with the format of the astronomical files, and the various astronomical packages and procedures being used for the above reduction.