35 research outputs found

    The Redshift Completeness of Local Galaxy Catalogs

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    There is considerable interest in understanding the demographics of galaxies within the local universe (defined, for our purposes, as the volume within a radius of 200 Mpc or z ≀ 0.05). In this pilot paper, using supernovae (SNe) as signposts to galaxies, we investigate the redshift completeness of catalogs of nearby galaxies. In particular, type Ia SNe are bright and are good tracers of the bulk of the galaxy population, as they arise in both old and young stellar populations. Our input sample consists of SNe with redshift ≀0.05, discovered by the flux-limited ASAS-SN survey. We define the redshift completeness fraction (RCF) as the number of SN host galaxies with known redshift prior to SN discovery, determined, in this case, via the NASA Extragalactic Database, divided by the total number of newly discovered SNe. Using SNe Ia, we find RCF=78±76\mathrm{RCF}=78{\pm }_{7}^{6}% (90% confidence interval) for z < 0.03. We examine the distribution of host galaxies with and without cataloged redshifts as a function of absolute magnitude and redshift, and, unsurprisingly, find that higher-z and fainter hosts are less likely to have a known redshift prior to the detection of the SN. However, surprisingly, some L∗{L}_{* } galaxies are also missing. We conclude with thoughts on the future improvement of RCF measurements that will be made possible from large SN samples resulting from ongoing and especially upcoming time-domain surveys

    Astropy: A Community Python Package for Astronomy

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    We present the first public version (v0.2) of the open-source and community-developed Python package, Astropy. This package provides core astronomy-related functionality to the community, including support for domain-specific file formats such as Flexible Image Transport System (FITS) files, Virtual Observatory (VO) tables, and common ASCII table formats, unit and physical quantity conversions, physical constants specific to astronomy, celestial coordinate and time transformations, world coordinate system (WCS) support, generalized containers for representing gridded as well as tabular data, and a framework for cosmological transformations and conversions. Significant functionality is under active development, such as a model fitting framework, VO client and server tools, and aperture and point spread function (PSF) photometry tools. The core development team is actively making additions and enhancements to the current code base, and we encourage anyone interested to participate in the development of future Astropy versions

    The Astropy Project: Building an inclusive, open-science project and status of the v2.0 core package

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    The Astropy project supports and fosters the development of open-source and openly-developed Python packages that provide commonly-needed functionality to the astronomical community. A key element of the Astropy project is the core package Astropy, which serves as the foundation for more specialized projects and packages. In this article, we provide an overview of the organization of the Astropy project and summarize key features in the core package as of the recent major release, version 2.0. We then describe the project infrastructure designed to facilitate and support development for a broader ecosystem of inter-operable packages. We conclude with a future outlook of planned new features and directions for the broader Astropy project

    An Implementation of the Digital Music Stand for Custom-Made On-Screen Music Manuscript Viewing

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    Part 7: First Mining Humanistic Data Workshop (MHDW 2012)International audienceAn implementation of the digital music stand (DMS) is presented in this invited tutorial. The DMS constitutes an optical music recognition (OMR) system whose principal aim is the custom-made on-screen presentation of music manuscripts (MMs). Aiming at performing the minimum necessary amount of MM processing, the DMS constitutes middle ground between full-processing classical commercial OMR systems/platforms and pure MM presentation systems. The DMS is intended for musicians and choir singers at all levels of music erudition, in both cases including those with visual impairments which cannot be corrected with glasses or contact lenses; music activities ranging from study, rehearsal and performance of individuals as well as of orchestras are accommodated. The DMS implementation stages are detailed, with performance accuracy, which is necessary for correct MM presentation, also being reported

    Astropy: A community Python package for astronomy

    No full text
    We present the first public version (v0.2) of the open-source and community-developed Python package, Astropy. This package provides core astronomy-related functionality to the community, including support for domain-specific file formats such as flexibl
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