9 research outputs found
Iris: an Extensible Application for Building and Analyzing Spectral Energy Distributions
Iris is an extensible application that provides astronomers with a
user-friendly interface capable of ingesting broad-band data from many
different sources in order to build, explore, and model spectral energy
distributions (SEDs). Iris takes advantage of the standards defined by the
International Virtual Observatory Alliance, but hides the technicalities of
such standards by implementing different layers of abstraction on top of them.
Such intermediate layers provide hooks that users and developers can exploit in
order to extend the capabilities provided by Iris. For instance, custom Python
models can be combined in arbitrary ways with the Iris built-in models or with
other custom functions. As such, Iris offers a platform for the development and
integration of SED data, services, and applications, either from the user's
system or from the web. In this paper we describe the built-in features
provided by Iris for building and analyzing SEDs. We also explore in some
detail the Iris framework and software development kit, showing how astronomers
and software developers can plug their code into an integrated SED analysis
environment.Comment: 18 pages, 8 figures, accepted for publication in Astronomy &
Computin
Managing Distributed Software Development in the Virtual Astronomical Observatory
The U.S. Virtual Astronomical Observatory (VAO) is a product-driven
organization that provides new scientific research capabilities to the
astronomical community. Software development for the VAO follows a lightweight
framework that guides development of science applications and infrastructure.
Challenges to be overcome include distributed development teams, part-time
efforts, and highly constrained schedules. We describe the process we followed
to conquer these challenges while developing Iris, the VAO application for
analysis of 1-D astronomical spectral energy distributions (SEDs). Iris was
successfully built and released in less than a year with a team distributed
across four institutions. The project followed existing International Virtual
Observatory Alliance inter-operability standards for spectral data and
contributed a SED library as a by-product of the project. We emphasize lessons
learned that will be folded into future development efforts. In our experience,
a well-defined process that provides guidelines to ensure the project is
cohesive and stays on track is key to success. Internal product deliveries with
a planned test and feedback loop are critical. Release candidates are measured
against use cases established early in the process, and provide the opportunity
to assess priorities and make course corrections during development. Also key
is the participation of a stakeholder such as a lead scientist who manages the
technical questions, advises on priorities, and is actively involved as a lead
tester. Finally, frequent scheduled communications (for example a bi-weekly
tele-conference) assure issues are resolved quickly and the team is working
toward a common visionComment: 7 pages, 2 figures, SPIE 2012 conferenc
Redshift-independent Distances in the NASA/IPAC Extragalactic Database: Methodology, Content, and Use of NED-D
Estimates of galaxy distances based on indicators that are independent of cosmological redshift are fundamental to astrophysics. Researchers use them to establish the extragalactic distance scale, to underpin estimates of the Hubble constant, and to study peculiar velocities induced by gravitational attractions that perturb the motions of galaxies with respect to the "Hubble flow" of universal expansion. In 2006 the NASA/IPAC Extragalactic Database (NED) began making available a comprehensive compilation of redshift-independent extragalactic distance estimates. A decade later, this compendium of distances (NED-D) now contains more than 100,000 individual estimates based on primary and secondary indicators, available for more than 28,000 galaxies, and compiled from over 2000 references in the refereed astronomical literature. This paper describes the methodology, content, and use of NED-D, and addresses challenges to be overcome in compiling such distances. Currently, 75 different distance indicators are in use. We include a figure that facilitates comparison of the indicators with significant numbers of estimates in terms of the minimum, 25th percentile, median, 75th percentile, and maximum distances spanned. Brief descriptions of the indicators, including examples of their use in the database, are given in an appendix
Providing comprehensive and consistent access to astronomical observatory archive data: the NASA archive model
Since the turn of the millennium a constant concern of astronomical archives have begun providing data to the public through standardized protocols unifying data from disparate physical sources and wavebands across the electromagnetic spectrum into an astronomical virtual observatory (VO). In October 2014, NASA began support for the NASA Astronomical Virtual Observatories (NAVO) program to coordinate the efforts of NASA astronomy archives in providing data to users through implementation of protocols agreed within the International Virtual Observatory Alliance (IVOA). A major goal of the NAVO collaboration has been to step back from a piecemeal implementation of IVOA standards and define what the appropriate presence for the US and NASA astronomy archives in the VO should be. This includes evaluating what optional capabilities in the standards need to be supported, the specific versions of standards that should be used, and returning feedback to the IVOA, to support modifications as needed.
We discuss a standard archive model developed by the NAVO for data archive presence in the virtual observatory built upon a consistent framework of standards defined by the IVOA. Our standard model provides for discovery of resources through the VO registries, access to observation and object data, downloads of image and spectral data and general access to archival datasets. It defines specific protocol versions, minimum capabilities, and all dependencies. The model will evolve as the capabilities of the virtual observatory and needs of the community change
Grid-Based Galaxy Morphology Analysis for the National Virtual Observatory
As part of the development of the National Virtual Observatory (NVO), a Data Grid for astronomy, we have developed a prototype science application to explore the dynamical history of galaxy clusters by analyzing the galaxies' morphologies. The purpose of the prototype is to investigate how Grid-based technologies can be used to provide specialized computational services within the NVO environment. In this paper we focus on the key enabling technology components, particularly Chimera and Pegasus which are used to create and manage the computational workflow that must be present to deal with the challenging application requirements. We illustrate how the components interplay with each other and can be driven from a special purpose application portal
Best Practices for Data Publication in the Astronomical Literature
16 pages, submitted to ApJSWe present an overview of best practices for publishing data in astronomy and astrophysics journals. These recommendations are intended as a reference for authors to help prepare and publish data in a way that will better represent and support science results, enable better data sharing, improve reproducibility, and enhance the reusability of data. Observance of these guidelines will also help to streamline the extraction, preservation, integration and cross-linking of valuable data from astrophysics literature into major astronomical databases, and consequently facilitate new modes of science discovery that will better exploit the vast quantities of panchromatic and multi-dimensional data associated with the literature. We encourage authors, journal editors, referees, and publishers to implement the best practices reviewed here, as well as related recommendations from international astronomical organizations such as the International Astronomical Union (IAU) and International Virtual Observatory Alliance (IVOA) for publication of nomenclature, data, and metadata. A convenient Checklist of Recommendations for Publishing Data in Literature is included for authors to consult before the submission of the final version of their journal articles and associated data files. We recommend that publishers of journals in astronomy and astrophysics incorporate a link to this document in their Instructions to Authors