63 research outputs found
IVOA Provenance data model: hints from the CTA Provenance prototype
We present the last developments on the IVOA Provenance data model, mainly
based on the W3C PROV concept. In the context of the Cherenkov astronomy, the
data processing stages imply both assumptions and comparison to dedicated
simulations. As a consequence, Provenance information is crucial to the end
user in order to interpret the high level data products. The Cherenkov
Telescope Array (CTA), currently in preparation, is thus a perfect test case
for the development of an IVOA standard on Provenance information. We describe
general use-cases for the computational Provenance in the CTA production
pipeline and explore the proposed W3C notations like PROV-N formats, as well as
Provenance access solutions.Comment: 4 pages, 3 figures, to appear in ADASS XXV proceedings, edited by N.
P. F. Lorente, & K. Shortridge (San Francisco: ASP), ASP Conf. Se
Implementation feedback of the IVOA Provenance data model
The IVOA Provenance Data model defines entities, agents and activities as
container classes to describe the provenance of datasets, with the executed
tasks and responsibilities attached to agents. It also provides a set of
classes to describe the activities type and their configuration template, as
well as the configuration applied effectively during the execution of a task.
Here we highlight lessons learned in the implementation of the CDS ProvHiPS
service distributing provenance metadata for the HST HiPS data collections, and
for the HST archive original images used to produce the HiPS tiles. ProvHiPS is
based on the ProvTAP protocol, the emerging TAP standard for distributing
provenance metadata. ProvTAP queries may rapidly become very complex. Various
graph representation strategies, including ad hoc solutions, triplestore and
SQL CTE have been considered and are discussed shortly.Comment: 4 pages, to appear in proceedings of ADASS XXIX, ASP Conf. Serie
Radio Astronomy visibility data discovery and access using IVOA standards
Enhancing interoperable data access to radio data has become a science
priority within the International Virtual Observatory Alliance (IVOA). This
lead to the foundation of the IVOA Radio astronomy Interest Group. Several
radio astronomers and project scientists enrolled in various projects (NRAO,
ASKAP, LOFAR, JIVE, ALMA, SKA, INAF, NenuFAR, etc.) have joined. Together they
are paving the way to a better integration of their services in the virtual
observatory (VO) infrastructure and propose extension of IVOA standards to help
achieving this goal. Calibrated radio datasets such as cubes, images, spectra
and time series can already be searched and retrieved using the ObsCore/ObsTAP
specification defined in the IVOA, or by data product-specific services like
SIAv2, SODA, SSA and ConeSearch. However, properties of radio visibility data
are not fully implemented in the VO landscape yet. We need specific features to
refine data discovery and selection that are adapted to radio astronomers'
need. In this context the VO team at the Centre de Donn\'{e}es astronomiques de
Strasbourg (CDS) proposes to consider the ObsCore/ObsTAP specification and to
establish cross-walks between the ObsCore and the existing Measurement Set (MS)
metadata profile for data discovery of radio visibility data (VD). In order to
account for the difference in granularity between radio VD datasets and
science-ready datasets of the VO, the approach splits a MS data file into a
list of datasets served by an ObsTAP service, thus enabling coarse grain
discovery in the multi-wavelength context. Radio specific metadata such as
number of antennae, frequency ranges, plane coverage plots,
frequency-phase and frequency-amplitude plots, primary and synthesized beams
are also provided either by adding column metadata or by using the DataLink
technique.Comment: 4 pages, 2 figures, ADASS XXX Conference Proceedings Nov 202
IVOA Recommendation: Data Model for Astronomical DataSet Characterisation
This document defines the high level metadata necessary to describe the
physical parameter space of observed or simulated astronomical data sets, such
as 2D-images, data cubes, X-ray event lists, IFU data, etc.. The
Characterisation data model is an abstraction which can be used to derive a
structured description of any relevant data and thus to facilitate its
discovery and scientific interpretation. The model aims at facilitating the
manipulation of heterogeneous data in any VO framework or portal. A VO
Characterisation instance can include descriptions of the data axes, the range
of coordinates covered by the data, and details of the data sampling and
resolution on each axis. These descriptions should be in terms of physical
variables, independent of instrumental signatures as far as possible.
Implementations of this model has been described in the IVOA Note available
at: http://www.ivoa.net/Documents/latest/ImplementationCharacterisation.html
Utypes derived from this version of the UML model are listed and commented in
the following IVOA Note:
http://www.ivoa.net/Documents/latest/UtypeListCharacterisationDM.html
An XML schema has been build up from the UML model and is available at:
http://www.ivoa.net/xml/Characterisation/Characterisation-v1.11.xsdComment: http://www.ivoa.ne
The ALADIN Interactive Sky Atlas
The Aladin interactive sky atlas, developed at CDS, is a service providing
simultaneous access to digitized images of the sky, astronomical catalogues,
and databases.
The driving motivation is to facilitate direct, visual comparison of
observational data at any wavelength with images of the optical sky, and with
reference catalogues.
The set of available sky images consists of the STScI Digitized Sky Surveys,
completed with high resolution images of crowded regions scanned at the MAMA
facility in Paris.
A Java WWW interface to the system is available at:
http://aladin.u-strasbg.fr/Comment: 8 pages, 3 Postscript figures; to be published in A&
IVOA Recommendation: IVOA Photometry Data Model
The Photometry Data Model (PhotDM) standard describes photometry filters,
photometric systems, magnitude systems, zero points and its interrelation with
the other IVOA data models through a simple data model. Particular attention is
given necessarily to optical photometry where specifications of magnitude
systems and photometric zero points are required to convert photometric
measurements into physical flux density units
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