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Dissertations / Theses on the topic 'Techniques: photometric'

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Published: 4 June 2021

Last updated: 25 July 2025

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1

Domeniconi, Federico. "Deep Learning Techniques applied to Photometric Stereo." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2020. http://amslaurea.unibo.it/20031/.

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La tesi si focalizza sullo studio dello stato dell’arte della fotometria stereo con deep learning: Self-calibrating Deep Photometric Stereo Networks. Il modello è composto è composto di due reti, la prima predice la direzione e l’intensità delle luci, la seconda predice le normali della superficie. L’obiettivo della tesi è individuare i limiti del modello e capire se possa essere modifcato per avere buone prestazioni anche in scenari reali. Il progetto di tesi è basato su fine-tuning, una tecnica supervisionata di transfer learning. Per questo scopo un nuovo dataset è stato creato acquisendo i

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Bezanson, Rachel, David A. Wake, Gabriel B. Brammer, et al. "LEVERAGING 3D-HST GRISM REDSHIFTS TO QUANTIFY PHOTOMETRIC REDSHIFT PERFORMANCE." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621218.

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We present a study of photometric redshift accuracy in the 3D-HST photometric catalogs, using 3D-HST grism redshifts to quantify and dissect trends in redshift accuracy for galaxies brighter than JH(IR) > 24 with an unprecedented and representative high-redshift galaxy sample. We find an average scatter of 0.0197 +/- 0.0003(1 + z) in the Skelton et al. photometric redshifts. Photometric redshift accuracy decreases with magnitude and redshift, but does not vary monotonically with color or stellar mass. The 1 sigma scatter lies between 0.01 and 0.03 (1 + z) for galaxies of all masses and colors

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Zou, Hu, Tianmeng Zhang, Zhimin Zhou, et al. "The First Data Release of the Beijing-Arizona Sky Survey." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/624694.

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The Beijing-Arizona Sky Survey (BASS) is a new wide-field legacy imaging survey in the northern Galactic cap using the 2.3 m Bok telescope. The survey will cover about 5400 deg(2) in the g and r bands, and the expected 5 sigma depths (corrected for the Galactic extinction) in these two bands are g = 24.0 and r = 23.4 mag (AB magnitude). BASS started observations in 2015 January. and had. completed about 41% of the. area as of 2016 July. The first data release contains calibrated images obtained in 2015 and 2016 and their corresponding single-epoch. and coadded catalogs. The actual depths of th

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Stritzinger, Maximilian. "Type Ia supernovae bolometric properties and new tools for photometric techniques /." [S.l.] : [s.n.], 2005. http://deposit.ddb.de/cgi-bin/dokserv?idn=979066697.

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Mason, Justin R. "In search of red dwarf stars application of three-color photometric techniques /." Muncie, IN : Ball State University, 2009. http://cardinalscholar.bsu.edu/659.

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Toyozumi, Hiroyuki Physics Faculty of Science UNSW. "The intra-pixel sensitivity variation of a CCD." Awarded by:University of New South Wales. School of Physics, 2005. http://handle.unsw.edu.au/1959.4/25995.

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The effect of Intra-pixel sensitivity variation (IPSV) in charge-coupled devices (CCDs) can be important in astronomical applications. This thesis studies the IPSV in a front-illuminated three-phase EEV05-20 CCD used in the Automated Patrol Telescope (APT), from multiple points of view. To explore the detailed sensitivity variation within pixels, the CCD was scanned using a 4 \mu meter diameter light beam in four colour bands: B, V, R and I. The resulting images clearly show the IPSVs due to the CCD electrode structure, and its dependence on wavelength. Unexpected ghost images appear in the s

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Li, Linlin, Shiyin Shen, Jinliang Hou, et al. "GALACTIC EXTINCTION AND REDDENING FROM THE SOUTH GALACTIC CAP u -BAND SKY SURVEY: u -BAND GALAXY NUMBER COUNTS AND u − r COLOR DISTRIBUTION." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623264.

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We study the integral Galactic extinction and reddening based on the galaxy catalog of the South Galactic Cap u-band Sky Survey (SCUSS), where u-band galaxy number counts and u - r color distribution are used to derive the Galactic extinction and reddening respectively. We compare these independent statistical measurements with the reddening map of Schlegel et al. (SFD) and find that both the extinction and reddening from the number counts and color distribution are in good agreement with the SFD results at low extinction regions (E(B - V)(SFD) < 0.12 mag). However, for high extinction regions

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8

Cartwright, Stephen J. "Application of digital image processing techniques to the photometric testing of vehicle headlamps." Thesis, Aston University, 1986. http://publications.aston.ac.uk/14614/.

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The aim of this Interdisciplinary Higher Degrees project was the development of a high-speed method of photometrically testing vehicle headlamps, based on the use of image processing techniques, for Lucas Electrical Limited. Photometric testing involves measuring the illuminance produced by a lamp at certain points in its beam distribution. Headlamp performance is best represented by an iso-lux diagram, showing illuminance contours, produced from a two-dimensional array of data. Conventionally, the tens of thousands of measurements required are made using a single stationary photodetector and

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Christiansen, Jessie L., Andrew Vanderburg, Jennifer Burt, et al. "Three’s Company: An Additional Non-transiting Super-Earth in the Bright HD 3167 System, and Masses for All Three Planets." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625817.

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HD 3167 is a bright (V = 8.9), nearby KO star observed by the NASA K2 mission (EPIC 220383386), hosting two small, short-period transiting planets. Here we present the results of a multi-site, multi-instrument radial-velocity campaign to characterize the HD 3167 system. The masses of the transiting planets are 5.02 +/- 0.38 M-circle plus for HD 3167 b, a hot super-Earth with a likely rocky composition (rho(b) = 5.6(-1.43)(+2.15) g cm(-3)), and 9.80(-1.24)(+1.30) M-circle plus for HD 3167 c, a warm sub-Neptune with a likely substantial volatile complement (rho(c) = 1.97(-0.59)(+0.94) g cm(-3)).

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Stefansson, Gudmundur, Suvrath Mahadevan, Leslie Hebb, et al. "Toward Space-like Photometric Precision from the Ground with Beam-shaping Diffusers." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/626043.

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We demonstrate a path to hitherto unachievable differential photometric precisions from the ground, both in the optical and near-infrared (NIR), using custom-fabricated beam-shaping diffusers produced using specialized nanofabrication techniques. Such diffusers mold the focal plane image of a star into a broad and stable top-hat shape, minimizing photometric errors due to non-uniform pixel response, atmospheric seeing effects, imperfect guiding, and telescope-induced variable aberrations seen in defocusing. This PSF reshaping significantly increases the achievable dynamic range of our observat

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Önehag, Anna. "Solar Type Stars as Calibrators : A Photometric and Spectroscopic Study on the Atmospheric Properties of Late-type Stars." Doctoral thesis, Uppsala universitet, Institutionen för fysik och astronomi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-158709.

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Detailed knowledge of solar-type stars is essential in the understanding of the evolutionary past, presence and future of the Sun as well as the formation of its planetary system. Moreover, solar-type stars are of key significance for the study of the evolution of the Galaxy. The ages of solar-type stars map the full galactic evolution. Their surface layers are well mixed and just little affected by the interior nuclear processes. They may therefore be used as samples of the gas from which the stars were once formed. Models of stellar atmospheres are used to derive fundamental stellar quantiti

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Kuhn, Rudolf Bruwer. "Photometric techniques for exoplanet detection: the construction and deployment of the KELT-South telescope." Doctoral thesis, University of Cape Town, 2014. http://hdl.handle.net/11427/12920.

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Includes bibliographical references.<br>In this thesis I present the work I performed during the initial construction and deployment of the second telescope in the KELT project and I report the results of the search for transiting exoplanets and variable stars using one of the first commissioning datasets obtained with the telescope. The KELT-South telescope is located in Sutherland, South Africa and construction started in 2008. The telescope has been operating at full capacity since 2010, after two commissioning seasons from late 2008 to early 2010. I developed all the code that allows it to

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Landon, Jr George V. "Innovative Techniques for Digitizing and Restoring Deteriorated Historical Documents." UKnowledge, 2008. http://uknowledge.uky.edu/gradschool_diss/599.

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Recent large-scale document digitization initiatives have created new modes of access to modern library collections with the development of new hardware and software technologies. Most commonly, these digitization projects focus on accurately scanning bound texts, some reaching an efficiency of more than one million volumes per year. While vast digital collections are changing the way users access texts, current scanning paradigms can not handle many non-standard materials. Documentation forms such as manuscripts, scrolls, codices, deteriorated film, epigraphy, and rock art all hold a wealth o

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Lee, Bomee, Mauro Giavalisco, Katherine Whitaker, et al. "The Intrinsic Characteristics of Galaxies on the SFR–M ∗ Plane at 1.2 < z < 4: I. The Correlation between Stellar Age, Central Density, and Position Relative to the Main Sequence." IOP PUBLISHING LTD, 2018. http://hdl.handle.net/10150/627039.

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We use the deep CANDELS observations in the GOODS North and South fields to revisit the correlations between stellar mass (M-*), star formation rate (SFR) and morphology, and to introduce a fourth dimension, the mass-weighted stellar age, in galaxies at 1.2 < z < 4. We do this by making new measures of M-*, SFR, and stellar age thanks to an improved SED fitting procedure that allows various star formation history for each galaxy. Like others, we find that the slope of the main sequence (MS) of star formation in the (M-*; SFR) plane bends at high mass. We observe clear morphological differences

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Stevenson, Kevin B., Michael R. Line, Jacob L. Bean та ін. "SPITZER PHASE CURVE CONSTRAINTS FOR WASP-43b AT 3.6 AND 4.5μm". IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623051.

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Previous measurements of heat redistribution efficiency (the ability to transport energy from a planet's highly irradiated dayside to its eternally dark nightside) show considerable variation between exoplanets. Theoretical models predict a positive correlation between heat redistribution efficiency and temperature for tidally locked planets; however, recent Hubble Space Telescope (HST) WASP-43b spectroscopic phase curve results are inconsistent with current predictions. Using the Spitzer Space Telescope, we obtained a total of three phase curve observations of WASP-43b (P = 0.813 days) at 3.6

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Graham, Matthew J., S. G. Djorgovski, Andrew J. Drake, et al. "Understanding extreme quasar optical variability with CRTS – I. Major AGN flares." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/625731.

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There is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present the results of a systematic search for major flares in active galactic nucleus (AGN) in the Catalina Real-time Transient Survey as part of a broader study into extreme quasar variability. Such flares are defined in a quantitative manner as being atop of the normal, stochastic variability of quasars. We have identified 51 events from over 900 000 known quasars and high-probability quasar candidates, typically lasting 9

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Attrill, K. J. "Ellipsometric and photometric techniques for the measurement of the optical constants of thin films and surfaces." Thesis, University of Bradford, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.376351.

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Evans, Thomas M., David K. Sing, Hannah R. Wakeford, et al. "DETECTION OF H2O AND EVIDENCE FOR TiO/VO IN AN ULTRA-HOT EXOPLANET ATMOSPHERE." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/614712.

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We present a primary transit observation for the ultra-hot (T-eq similar to 2400 K) gas giant expolanet WASP-121b, made using the Hubble Space Telescope Wide Field Camera 3 in spectroscopic mode across the 1.12-1.64 mu m wavelength range. The 1.4 mu m water absorption band is detected at high confidence (5.4 sigma) in the planetary atmosphere. We also reanalyze ground-based photometric light curves taken in the B, r', and z' filters. Significantly deeper transits are measured in these optical bandpasses relative to the near-infrared wavelengths. We conclude that scattering by high-altitude haz

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Larionov, V. M., M. Villata, C. M. Raiteri, et al. "Exceptional outburst of the blazar CTA 102 in 2012: the GASP–WEBT campaign and its extension." OXFORD UNIV PRESS, 2016. http://hdl.handle.net/10150/621728.

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After several years of quiescence, the blazar CTA 102 underwent an exceptional outburst in 2012 September-October. The flare was tracked from gamma-ray to near-infrared (NIR) frequencies, including Fermi and Swift data as well as photometric and polarimetric data from several observatories. An intensive Glast-Agile support programme of the Whole Earth Blazar Telescope (GASP-WEBT) collaboration campaign in optical and NIR bands, with an addition of previously unpublished archival data and extension through fall 2015, allows comparison of this outburst with the previous activity period of this b

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Obermeier, Christian, Thomas Henning, Joshua E. Schlieder, et al. "K2 DISCOVERS A BUSY BEE: AN UNUSUAL TRANSITING NEPTUNE FOUND IN THE BEEHIVE CLUSTER." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/622698.

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Open clusters have been the focus of several exoplanet surveys, but only a few planets have so far been discovered. The Kepler spacecraft revealed an abundance of small planets around small cool stars, therefore, such cluster members are prime targets for exoplanet transit searches. Kepler's new mission, K2, is targeting several open clusters and star-forming regions around the ecliptic to search for transiting planets around their low-mass constituents. Here, we report the discovery of the first transiting planet in the intermediate-age (800 Myr) Beehive cluster (Praesepe). K2-95 is a faint (

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Sinukoff, Evan, Andrew W. Howard, Erik A. Petigura, et al. "ELEVEN MULTIPLANET SYSTEMS FROM K2 CAMPAIGNS 1 AND 2 AND THE MASSES OF TWO HOT SUPER-EARTHS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621388.

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We present a catalog of 11 multiplanet systems from Campaigns 1 and 2 of the K2 mission. We report the sizes and orbits of 26 planets split between seven two-planet systems and four three-planet systems. These planets stem from a systematic search of the K2 photometry for all dwarf stars observed by K2 in these fields. We precisely characterized the host stars with adaptive optics imaging and analysis of high-resolution optical spectra from Keck/HIRES and medium-resolution spectra from IRTF/SpeX. We confirm two planet candidates by mass detection and validate the remaining 24 candidates to >99

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Pearson, Kyle A., Leon Palafox, and Caitlin A. Griffith. "Searching for exoplanets using artificial intelligence." OXFORD UNIV PRESS, 2018. http://hdl.handle.net/10150/627143.

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In the last decade, over a million stars were monitored to detect transiting planets. Manual interpretation of potential exoplanet candidates is labour intensive and subject to human error, the results of which are difficult to quantify. Here we present a new method of detecting exoplanet candidates in large planetary search projects that, unlike current methods, uses a neural network. Neural networks, also called 'deep learning' or 'deep nets', are designed to give a computer perception into a specific problem by training it to recognize patterns. Unlike past transit detection algorithms, dee

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Karalidi, Theodora, Dániel Apai, Mark S. Marley, and Esther Buenzli. "MAPS OF EVOLVING CLOUD STRUCTURES IN LUHMAN 16AB FROM HST TIME-RESOLVED SPECTROSCOPY." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621380.

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WISE J104915.57-531906.1 is the nearest brown dwarf binary to our solar system, consisting of two brown dwarfs in the L/T transition: Luhman 16A and B. In this paper, we present the first map of Luhman 16A, and maps of Luhman 16B for two epochs. Our maps were created by applying Aeolus, a Markov-Chain Monte Carlo code that maps the top-of-the-atmosphere (TOA) structure of brown dwarf and other ultracool atmospheres, to light curves of Luhman 16A and B using the Hubble Space Telescope's G141 and G102 grisms. Aeolus retrieved three or four spots in the TOA of Luhman 16A and B, with a surface cov

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Bell, Taylor J., Nikolay Nikolov, Nicolas B. Cowan, et al. "The Very Low Albedo of WASP-12b from Spectral Eclipse Observations with Hubble." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/625800.

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We present an optical eclipse observation of the hot Jupiter WASP-12b using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. These spectra allow us to place an upper limit of A(g) < 0.064 (97.5% confidence level) on the planet's white light geometric albedo across 290-570 nm. Using six wavelength bins across the same wavelength range also produces stringent limits on the geometric albedo for all bins. However, our uncertainties in eclipse depth are similar to 40% greater than the Poisson limit and may be limited by the intrinsic variability of the Sun-like host sta

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Crossfield, Ian J. M., David R. Ciardi, Erik A. Petigura, et al. "197 CANDIDATES AND 104 VALIDATED PLANETS IN K2's FIRST FIVE FIELDS." IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/624074.

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We present 197 planet candidates discovered using data from the first year of the NASA K2 mission (Campaigns 0-4), along with the results of an intensive program of photometric analyses, stellar spectroscopy, high-resolution imaging, and statistical validation. We distill these candidates into sets of 104 validated planets (57 in multi-planet systems), 30 false positives, and 63 remaining candidates. Our validated systems span a range of properties, with median values of R-P = 2.3 R-circle plus, P = 8.6 days, T-eff = 5300 K, and Kp = 12.7 mag. Stellar spectroscopy provides precise stellar and

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Wong, Ian, Heather A. Knutson, Tiffany Kataria та ін. "3.6 AND 4.5 μm SPITZER PHASE CURVES OF THE HIGHLY IRRADIATED HOT JUPITERS WASP-19b AND HAT-P-7b". IOP PUBLISHING LTD, 2016. http://hdl.handle.net/10150/621241.

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We analyze full-orbit phase curve observations of the transiting hot Jupiters WASP-19b and HAT-P-7b at 3.6 and 4.5 mu m, obtained using the Spitzer Space Telescope. For WASP-19b, we measure secondary eclipse depths of 0.485% +/- 0.024% and 0.584% +/- 0.029% at 3.6 and 4.5 mu m, which are consistent with a single blackbody with effective temperature 2372 +/- 60 K. The measured 3.6 and 4.5 mu m secondary eclipse depths for HAT-P-7b are 0.156% +/- 0.009% and 0.190% +/- 0.006%, which are well described by a single blackbody with effective temperature 2667 +/- 57 K. Comparing the phase curves to th

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Cunha, Evandro Fernandes da. "Implementação de um aparato experimental para medição de instabilidade em superfície livre com fluido não-Newtoniano." Ilha Solteira, 2018. http://hdl.handle.net/11449/158313.

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Orientador: Geraldo de Freitas Maciel<br>Resumo: Esta tese de doutorado traz uma abordagem experimental sobre mecanismos de geração, desenvolvimento e propagação em canal de instabilidade na superfície livre de um escoamento de fluido não-Newtoniano. Estas instabilidades, quando evoluem para um padrão estável, exibem comprimento, amplitude e celeridade bem definidos, sendo denominadas roll waves. Na literatura existe uma lacuna no que diz respeito às medições destes fenômenos em condições controladas de laboratório, e com pouquíssimos registros, quando presentes em eventos naturais. Assim, bus

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Benneke, Björn, Michael Werner, Erik Petigura, et al. "SPITZER OBSERVATIONS CONFIRM AND RESCUE THE HABITABLE-ZONE SUPER-EARTH K2-18b FOR FUTURE CHARACTERIZATION." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/624028.

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The recent detections of two transit events attributed to the super-Earth candidate K2-18b have provided the unprecedented prospect of spectroscopically studying a habitable-zone planet outside the solar system. Orbiting a nearby M2.5 dwarf and receiving virtually the same stellar insolation as Earth, K2-18b would be a prime candidate for the first detailed atmospheric characterization of a habitable-zone exoplanet using the Hubble Space Telescope (HST) and James Webb Space Telescope (JWST). Here, we report the detection of a third transit of K2-18b near the predicted transit time using the Sp

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Ramiaramanantsoa, Tahina, Anthony F. J. Moffat, Robert Harmon та Richard Ignace. "BRITE-Constellation High-Precision Time-Dependent Photometry of the Early O-Type Supergiant ζ Puppis Unveils the Photospheric Drivers of Its Small- and Large-Scale Wind Structures". Digital Commons @ East Tennessee State University, 2017. https://dc.etsu.edu/etsu-works/2724.

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From 5.5 months of dual-band optical photometric monitoring at the 1 mmag level, BRITE-Constellation has revealed two simultaneous types of variability in the O4I(n)fp star ζ Puppis: one single periodic non-sinusoidal component superimposed on a stochastic component. The monoperiodic component is the 1.78-d signal previously detected by Coriolis/Solar Mass Ejection Imager, but this time along with a prominent first harmonic. The shape of this signal changes over time, a behaviour that is incompatible with stellar oscillations but consistent with rotational modulation arising from evolving brig

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Burke, Christopher J. "Survey for transiting extrasolar planets in stellar systems stellar and planetary content of the Open Cluster NGC 1245 /." Columbus, Ohio : Ohio State University, 2005. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1132168623.

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Turner, Jake D., Robin M. Leiter, Lauren I. Biddle, et al. "Investigating the physical properties of transiting hot Jupiters with the 1.5-m Kuiper Telescope." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/626279.

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We present new photometric data of 11 hot Jupiter transiting exoplanets (CoRoT-12b, HATP-5b, HAT-P-12b, HAT-P-33b, HAT-P-37b, WASP-2b, WASP-24b, WASP-60b, WASP-80b, WASP-103b and XO-3b) in order to update their planetary parameters and to constrain information about their atmospheres. These observations of CoRoT-12b, HAT-P-37b and WASP-60b are the first follow-up data since their discovery. Additionally, the first near-UV transits of WASP-80b and WASP-103b are presented. We compare the results of our analysis with previous work to search for transit timing variations (TTVs) and a wavelength de

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Hallakoun, N., (许偲艺) S. Xu, D. Maoz, et al. "Once in a blue moon: detection of ‘bluing' during debris transits in the white dwarf WD 1145+017." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/625505.

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The first transiting planetesimal orbiting a white dwarf was recently detected in K2 data of WD 1145+017 and has been followed up intensively. The multiple, long and variable transits suggest the transiting objects are dust clouds, probably produced by a disintegrating asteroid. In addition, the system contains circumstellar gas, evident by broad absorption lines, mostly in the u' band, and a dust disc, indicated by an infrared excess. Here we present the first detection of a change in colour of WD 1145+017 during transits, using simultaneous multiband fast-photometry ULTRACAM measurements ove

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Shan, Yutong, Jennifer C. Yee, Brendan P. Bowler, et al. "The Multiplicity of M Dwarfs in Young Moving Groups." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/627110.

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We image 104 newly identified low-mass (mostly M-dwarf) pre-main sequence (PMS) members of nearby young moving groups (YMGs) with Magellan Adaptive Optics (MagAO) and identify 27 stellar binaries with instantaneous projected separation as small as 40 mas. Fifteen were previously unknown. The total number of multiple systems in this sample including spectroscopic and visual binaries from the literature is 36, giving a raw stellar multiplicity rate of at least 35(-4)(+5)% for this population. In the separation range of roughly 1-300 au in which infrared AO imaging is most sensitive, the raw mult

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Ferreira, Joao. "Occultations stellaires. Une nouvelle approche grâce à la mission Gaia." Thesis, Université Côte d'Azur, 2020. http://www.theses.fr/2020COAZ4084.

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Les astéroïdes participent à la compréhension de plusieurs problèmes clés liés à la science du système solaire et à l’environnement spatial de notre planète, tels que les conditions du système solaire lors de sa formation, l’apport d’eau et de molécules organiques sur la Terre, le danger potentiel des astéroïdes proches de la Terre et leur rôle dans l’influence du climat de la Terre.Les occultations stellaires sont une occasion unique d’obtenir du sol une astrométrie astéroïde très précise, proche de la performance de Gaia, ainsi que des formes pour les astéroïdes. Lorsqu’un astéroïde cache la

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Rydberg, Claes-Erik. "Gravitational lensing as a probe of the first stars and galaxies." Doctoral thesis, Stockholms universitet, Institutionen för astronomi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-110070.

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This thesis investigates the potential for detection and identification of primordial stars, galaxies, and supernovae at high redshift. Simulations indicate that the first Population III stars should appear in minihalos of mass M = 105-106 Msol at z ≈ 10-30. To assess the detectability of these objects, theoretical models of these stars and their surrounding HII regions are used. We assess the plausibility of detection with the upcoming James Webb Space Telescope (JWST), using the gravitational lensing provided by the galaxy cluster MACSJ0717.5+3745. The conclusion is that the detection of the

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Joner, Michael Deloss. "High-Quality Broadband BVRI Photometry of Benchmark Open Clusters." BYU ScholarsArchive, 2011. https://scholarsarchive.byu.edu/etd/2495.

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Photometric techniques are often used to observe stars and it can be demonstrated that fundamental stellar properties can be observationally determined using calibrated sets of photometric data. Many of the most powerful techniques utilized to calibrate stellar photometry employ the use of stars in clusters since the individual stars are believed to have many common properties such as age, composition, and approximate distance. Broadband photometric Johnson/Cousins BVRI observations are presented for several nearby open clusters. The new photometry has been tested for consistency relative to a

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Bell, Cameron Pearce MacDonald. "A critical assessment of ages derived using pre-main-sequence isochrones in colour-magnitude diagrams." Thesis, University of Exeter, 2012. http://hdl.handle.net/10036/4017.

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In this thesis a critical assessment of the ages derived using theoretical pre-main-sequence (pre-MS) stellar evolutionary models is presented by comparing the predictions to the low-mass pre-MS population of 14 young star-forming regions (SFRs) in colour-magnitude diagrams (CMDs). Deriving pre-MS ages requires precise distances and estimates of the reddening. Therefore, the main-sequence (MS) members of the SFRs have been used to derive a self-consistent set of statistically robust ages, distances and reddenings with associated uncertainties using a maximum-likelihood fitting statistic and MS

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Wit, Julien de, Nikole K. Lewis, Heather A. Knutson, et al. "Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/624378.

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Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet's atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet-star interactions in HAT-P-2's eccentric planetary system gained from the analysis of similar to 350 hr of 4.5 mu m observations with the Spitzer Space Telescope. The observations show no

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Papakonstantinou, Nikolaos. "Investigation of variable Ap Stars in TESS continuous viewing zone." Thesis, Uppsala universitet, Observationell astrofysik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-441349.

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Grosset, Lucas. "Observations extragalactiques avec optique adaptative : polarisation dans les noyaux actifs de Galaxie et étude des super amas d'étoiles." Thesis, Paris Sciences et Lettres (ComUE), 2017. http://www.theses.fr/2017PSLEO004/document.

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Malgré l’existence de modèles précis, notre connaissance des structures à petite échelle des galaxies est toujours limitée par le manque de preuves observationnelles. Les progrès instrumentaux ont permis d’atteindre une haute résolution angulaire à l’aide des nouvelles générations de télescopes, mais celle-ci est restreinte à un faible nombre de cibles extragalactiques à causes des besoins de l’Optique Adaptative (OA). En effet, afin de permettre une mesure efficace du front d’onde, l’OA requiert une source brillante et ponctuelle proche de la cible scientifique, typiquement en dessous de 30 .

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Hill, David T. "The optical and NIR luminous energy output of the Universe : the creation and utilisation of a 9 waveband consistent sample of galaxies using UKIDSS and SDSS observations with the GAMA and MGC spectroscopic datasets." Thesis, University of St Andrews, 2011. http://hdl.handle.net/10023/1696.

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Theories of how galaxies form and evolve depend greatly on constraints provided by observations. However, when those observations come from different datasets, systematic offsets may occur. This causes difficulties measuring variations in parameters between filters. In this thesis I present the variation in total luminosity density with wavelength in the nearby Universe (z<0.1), produced from a consistent reanalysis of NIR and optical observations, taken from the MGC, UKIDSS and SDSS surveys. I derive luminosity distributions, best-fitting Schechter function parameterisations and total luminos

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Smart, R. L., D'aniel Apai, J. Davy Kirkpatrick, et al. "Parallaxes and infrared photometry of three Y0 dwarfs." OXFORD UNIV PRESS, 2017. http://hdl.handle.net/10150/624429.

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We have followed up the three Y0 dwarfs WISEPA J041022.71+150248.5, WISEPA J173835.53+273258.9 and WISEPC J205628.90+145953.3 using the United Kingdom Infrared Telescope Wide Field Camera. We find parallaxes that are more consistent and accurate than previously published values. We estimate absolute magnitudes in photometric passbands from Y to W3 and find them to be consistent between the three Y0 dwarfs indicating that the inherent cosmic absolute magnitude spread of these objects is small. We examine the Mauna Kea Observatory system J magnitudes over the 4 yr time line and find small but si

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Khayamian, Taghi. "Electrospray as a new sample introduction technique for the flame photometric detector." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24775.pdf.

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Bony, Alexandre. "Modélisation de l'interaction lumière/matière pour l'analyse de surfaces rugueuses texturées par stéréo photométrie." Thesis, Poitiers, 2013. http://www.theses.fr/2013POIT2301/document.

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Les techniques de reconstruction 3d sont devenues incontournables pour des applicationstelles que la caractérisation et l'analyse de surfaces. Les travaux réalisés au coursde cette thèse ont pour objectif d'améliorer la qualité des reconstructions 3d par stéréophotométrie.Cette méthode repose sur deux principes, l'inversion d'un modèle d'interactionlumière/matière (BRDF) et la configuration d'un système d'éclairage et de prises de vues.Pour des surfaces diffuses, la stéréo-photométrie est réalisée à partir d'un minimum detrois images acquises d'un point de vue fixe pour des directions d'éclair

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Osborn, James. "Proﬁling the turbulent atmosphere and novel correction techniques for imaging and photometry in astronomy". Thesis, Durham University, 2010. http://etheses.dur.ac.uk/513/.

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The turbulent atmosphere has two detrimental eﬀects in astronomy. The phase aberration induced by the turbulence broaden the point spread function (PSF) and limits the resolution for imaging. If there is strong turbulence high in the atmosphere then these phase aberration propagate and develop into intensity fluctuations (scintillation). This thesis describes three novel instruments related to these problems associated with atmospheric turbulence. The ﬁrst is an optical turbulence proﬁler to measure the turbulence strength and its position within the atmospheric surface layer in real-time. The

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Fu, Nicole Christina. "Physical Properties of Massive, Star-Forming Galaxies When the Universe Was Only Two Billion Years Old." Thèse, Université d'Ottawa / University of Ottawa, 2011. http://hdl.handle.net/10393/19956.

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Due to the finite speed of light and a vast, expanding universe, telescopes are just now receiving the light emitted by galaxies as they were forming in the very early universe. The light from these galaxies has been redshifted (stretched to longer, redder wavelengths) as a result of its journey through expanding space. Using sophisticated techniques and exceptional multi-wavelength optical and infrared data, we isolate a population of 378 galaxies in the process of formation when the Universe was only two billion years old. By matching the distinctive properties of the light spectra of the

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Garcia, E. Victor, Thayne Currie, Olivier Guyon, et al. "SCExAO AND GPI Y JH BAND PHOTOMETRY AND INTEGRAL FIELD SPECTROSCOPY OF THE YOUNG BROWN DWARF COMPANION TO HD 1160." IOP PUBLISHING LTD, 2017. http://hdl.handle.net/10150/623097.

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We present high signal-to-noise ratio, precise Y JH photometry and Y band (0.957-1.120 mu m) spectroscopy of HD 1160 B, a young substellar companion discovered from the Gemini NICI Planet Finding Campaign using the Subaru Coronagraphic Extreme Adaptive Optics instrument and the Gemini Planet Imager. HD 1160 B has typical mid-M dwarf-like infrared colors and a spectral type of M5.5(-0.5)(+1.0), where the blue edge of our Y band spectrum rules out earlier spectral types. Atmospheric modeling suggests HD 1160 B has an effective temperature of 3000-3100 K, a surface gravity of log g - 4-4.5, a rad

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Demitri, Nevine [Verfasser], Abdelhak M. [Akademischer Betreuer] Zoubir, and Hamid [Akademischer Betreuer] Krim. "Signal and Image Processing Techniques for Image-Based Photometry With Application to Diabetes Care / Nevine Demitri. Betreuer: Abdelhak M. Zoubir ; Hamid Krim." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2016. http://d-nb.info/1113183470/34.

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Lindgren, Sara. "Metallicity determination of M dwarfs." Doctoral thesis, Uppsala universitet, Observationell astrofysik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-332102.

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M dwarfs constitute around 70% of all stars in the local Galaxy. Their multitude together with their long main-sequence lifetimes make them important for studies of global properties of the Galaxy such as the initial mass function or the structure and kinematics of stellar populations. In addition, the exoplanet community is showing an increasing interest for those small, cold stars. However, very few M dwarfs are well characterized, and in the case of exoplanetary systems the stellar parameters have a direct influence on the derived planet properties. Stellar parameters of M dwarfs are diffic

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Skuljan, Ljiljana. "R Coronae Borealis stars : characteristics of their decline phase." Thesis, University of Canterbury. Physics and Astronomy, 2001. http://hdl.handle.net/10092/1308.

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R Coronae Borealis (RCB) stars belong to a rare class of variable stars characterized by sudden and unpredictable declines, which are believed to be caused by dust cloud obscuration. In spite of the fact that these stars are so rare (only about 40 are known in our Galaxy), there are many reasons for investigating them. The unusual variability and peculiar chemical composition make them unique among all known types of variable stars. Their evolution and the nature of their unpredictable minima are still not entirely understood. Very few observations of RCB stars during the decline phase exist.

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