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

Mapper les données de VOTables sur des modèle de données: Implementation status et prospectives

International audienceModel Instances in VOTables (MIVOT) is a VO standard that defines a syntax to map VOTable data to any data model serialised in VODML (Virtual Observatory Data Modeling Language). This annotation schema operates as a bridge between data and models. It associates both VOTable metadata and data to model elements (class, attributes, types, etc.). It also brings up VOTable data or metadata that were possibly missing in the table, e.g., accurate description of a coordinate system or curation tracing. MIVOT became an IVOA recommendation in June 2023. Having this standard was necessary to exercise data models against real data and to make the data interpretation easier by using code based with shared models. This paper presents our ongoing developments : reading and writing MIVOT annotations with a CDS RUST library, reading and interpreting annotations with AstroPy/PyVO and creating an add-on to the VOLLT TAP library able to annotate query responses on the fly.Model Instances in VOTables (MIVOT) est une norme VO qui définit une syntaxe permettant de faire correspondre les données VOTables à n'importe quel modèle de données sérialisé en VODML (Virtual Observatory Data Modeling Language). Ce schéma d'annotation sert de pont entre les données et les modèles. Il associe les métadonnées et les données VOTable aux éléments du modèle (classes, attributs, types, etc.). Il fait également ressortir les données ou métadonnées VOTable qui pourraient manquer dans la table, par exemple la description précise d'un système de coordonnées ou le suivi de la conservation. MIVOT est devenu une recommandation de l'IVOA en juin 2023. Il était nécessaire d'avoir cette norme pour exercer les modèles de données contre des données réelles et pour faciliter l'interprétation des données en utilisant un code basé sur des modèles partagés. Cet article présente nos développements en cours : lecture et écriture des annotations MIVOT avec une bibliothèque CDS RUST, lecture et interprétation des annotations avec AstroPy/PyVO et création d'un add-on à la bibliothèque VOLLT TAP capable d'annoter les réponses aux requêtes à la volée

The Chandra X‐Ray Observatory Resolves the X‐Ray Morphology and Spectra of a Jet in PKS 0637-752

The core-dominated radio-loud quasar PKS 0637-752 (z = 0.654) was the first celestial object observed with the Chandra X-Ray Observatory, offering the early surprise of the detection of a remarkable X-ray jet. Several observations with a variety of detector configurations contribute to a total exposure time with the Chandra ACIS of about 100 ks. A spatial analysis of all the available X-ray data, making use of Chandra's spatial resolving power of about 0farcs4, reveals a jet that extends about 10'' to the west of the nucleus. At least four X-ray knots are resolved along the jet, which contains about 5% of the overall X-ray luminosity of the source. Previous observations of PKS 0637-752 in the radio band had identified a kiloparsec-scale radio jet extending to the west of the quasar. The X-ray and radio jets are similar in shape, intensity distribution, and angular structure out to about 9'', after which the X-ray brightness decreases more rapidly and the radio jet turns abruptly to the north. The X-ray luminosity of the total source is log LX ≈ 45.8 ergs s-1 (2-10 keV) and appears not to have changed since it was observed with ASCA in 1996 November. We present the results of fitting a variety of emission models to the observed spectral distribution, comment on the nonexistence of emission lines recently reported in the ASCA observations of PKS 0637-752, and briefly discuss plausible X-ray emission mechanisms.Astronom