5 resultados para Supercosmos Sky Survey

em QSpace: Queen's University - Canada


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Halo white dwarfs remain one of the least studied stellar populations in the Milky Way because of their faint luminosities. Recent work has uncovered a population of hot white dwarfs which are thought to be remnants of low-mass Population II stars. This thesis uses optical data from the Next Generation Virgo Cluster Survey (NGVS) and ultravoilet data from the GALEX Ultraviolet Virgo Cluster Survey (GUViCS) to select candidates which may belong to this population of recently formed halo white dwarfs. A colour selection was used to separate white dwarfs from QSOs and main-sequence stars. Photometric distances are calculated using model colour-absolute magnitude relations. Proper motions are calculated by using the difference in positions between objects from the Sloan Digital Sky Survey and the NGVS. The proper motions are combined with the calculated photometric distances to calculate tangential velocities, as well as approximate Galactic space velocities. White dwarf candidates are characterized as belonging to either the disk or the halo using a variety of methods, including calculated scale heights (z> 1 kpc), tangential velocities (vt >200 km/s), and their location in (V,U) space. The 20 halo white dwarf candidates which were selected using Galactic space velocities are analyzed, and their colours and temperatures suggest that these objects represent some of the youngest white dwarfs in the Galactic halo.

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We present an extensive photometric catalog for 548 CALIFA galaxies observed as of the summer of 2015. CALIFA is currently lacking photometry matching the scale and diversity of its spectroscopy; this work is intended to meet all photometric needs for CALIFA galaxies while also identifying best photometric practices for upcoming integral field spectroscopy surveys such as SAMI and MaNGA. This catalog comprises gri surface brightness profiles derived from Sloan Digital Sky Survey (SDSS) imaging, a variety of non-parametric quantities extracted from these pro files, and parametric models fitted to the i-band pro files (1D) and original galaxy images (2D). To compliment our photometric analysis, we contrast the relative performance of our 1D and 2D modelling approaches. The ability of each measurement to characterize the global properties of galaxies is quantitatively assessed, in the context of constructing the tightest scaling relations. Where possible, we compare our photometry with existing photometrically or spectroscopically obtained measurements from the literature. Close agreement is found with Walcher et al. (2014), the current source of basic photometry and classifications of CALIFA galaxies, while comparisons with spectroscopically derived quantities reveals the effect of CALIFA's limited field of view compared to broadband imaging surveys such as the SDSS. The colour-magnitude diagram, star formation main sequence, and Tully-Fisher relation of CALIFA galaxies are studied, to give a small example of the investigations possible with this rich catalog. We conclude with a discussion of points of concern for ongoing integral field spectroscopy surveys and directions for future expansion and exploitation of this work.

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Queen's University Library was one of 202 libraries, including 57 members of the Association of Research Libraries (ARL), to survey its users in spring 2004 using the LibQUAL+ survey instrument. LibQUAL+ was designed by ARL to assist libraries in assessing the quality of their services and identifying areas for improvement. # Overall: Queen's scored higher than the average for all ARL participants and 1st among the 2004 Canadian participants. This relatively high rating is due to very high scores in the dimensions of Library as Place and Affect of Service. However, there is considerable need for improvement in the area of Information Control where Queen's rated well below the ARL average. # Affect of Service: Queen's strong overall ratings are supported by the many respondent comments praising customer service throughout the system. The ratings and survey comments indicate greatest appreciation by faculty and more experienced students (e.g. graduate students) for the instruction and on-site services provided by the libraries. The ratings also indicate that undergraduates, growing up with the web, want and expected to be able to access library resources independently and do not value these services as highly. The comments also indicated some specific areas for improvement throughout the library system. # Library as Place : All Queen's libraries except for Law ranked well above the ARL and Canadian averages. Overall, Library as Place ranked lowest in importance among the service dimensions for all ARL participants including Queen's. Comparative analysis of LibQUAL results since the survey began shows a decline in “desired” ratings for Library as Place. However, undergraduates continue to give strong "desired" ratings to certain aspects of Library as Place and a relatively high rating for "minimum expected" service. The comments from Queen's survey respondents and ARL's analyses of focus groups indicate that undergraduates value the library much more as a place to study and work with peers rather than for its on-site resources and services. # Information Control: This is the area in greatest need of attention. While it ranked highest in importance for all user groups by a wide margin, Queen's performed poorly in this category. Overall, Queen's ranked far below both the ARL average and the top three Canadian scores. However, the major dissatisfaction was concentrated in the humanities/social sciences (Stauffer primary users) and the health sciences (Bracken primary users) where the overall rating of perceived service quality ranked below the minimum expected service rating. Primary users of the Education, Engineering/Science and Law libraries rated this service dimension higher than the ARL average. The great success of the Canadian National Site License Program (CNSLP) is reflected in the high overall rating generated by Engineering/Science Library users. The low ratings from the humanities and social sciences are supported by respondents' comments and are generally consistent with other ARL participants.

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Analysis of 2007 LibQUAL+ results from the survey conducted by Queen's University in February 2007.

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Summary of the finding from the 2007 Queen's LibQUAL+ survey and action items developed by the Library.