IVOA Newsletter - Octobre 2014 (pdf)

Created: September 30, 2014 - 22:01 UTC

Subscribe | Newsletter archives | Write to the editors
IVOA Newsletter Editors: Mark G. Allen, Deborah Baines, Sarah Emery Bunn, Chenzou Cui, August Muench, Mark Taylor & Ivan Zolotukhin.

The International Virtual Observatory Alliance (IVOA) was formed in June 2002 with a mission to facilitate the international coordination and collaboration necessary for the development and deployment of the tools, systems and organizational structures necessary to enable the international utilization of astronomical archives as an integrated and interoperating virtual observatory. The IVOA now comprises 20 VO programs from Argentina, Armenia, Australia, Brazil, Canada, Chile, China, Europe, France, Germany, Hungary, India, Italy, Japan, Russia, South Africa, Spain, Ukraine, the United Kingdom, and the United States and an inter-governmental organization (ESA). Membership is open to other national and international programs according to the IVOA Guidelines for Participation. You can read more about the IVOA and what we do at http://ivoa.net/about/.

What is the VO?

The Virtual Observatory (VO) aims to provide a research environment that will open up new possibilities for scientific research based on data discovery, efficient data access, and interoperability. The vision is of global astronomy archives connected via the VO to form a multiwavelength digital sky that can be searched, visualized, and analyzed in new and innovative ways. VO projects worldwide working toward this vision are already providing science capabilities with new tools and services. This newsletter, aimed at astronomers, highlights VO tools and technologies for doing astronomy research, recent papers, and upcoming events.

IVOA news

Beyond the US VAO project

Funding for the US Virtual Astronomical Observatory project discontinued at the end of September 2014. The legacy of the VAO will be preserved by a combination of efforts. Starting on October 1, the NASA archives began sustaining key components of the US VO infrastructure developed by the VAO, including the website, the registry, and service monitors. The NASA archives will also take an active role in the IVOA going forward.

All software, documentation, and other digital assets developed under the VAO is stored in the VAO Project Repository. Many VAO-developed tools and services will be sustained by the organizations that developed them within the VAO collaboration. For a complete list of these tools and services, and more information about the VAO closeout and continuation, please see the US VAO website summary.

Three more VO schools in Spain

The Spanish Virtual Observatory has organized in the last months two VO schools in research institutes (Cantabria, June 2014; Valencia; July 2014) and one school in the framework of the Scientific Meeting of the Spanish Astronomical Society (Teruel, September 2014) with an attendance of more than 75 people. The main goal of the schools was to expose participants to the variety of VO tools and services available today so that they can use them efficiently for their own research. To achieve this goal, VO experts lecture and tutor the participants on the usage of such tools. Real life examples of scientific applications are given, some of them selected from the science cases proposed by the participants. More information on these meetings can be found on the SVO website.

First SVO workshop on data publishing

The Spanish Virtual Observatory organised in March 2014 a workshop on how to publish data in the VO. The workshop had a twofold objective: on one hand, to train participants on the usage of the publishing tools developed by the SVO through “hands-on” sessions in which they learn how to develop a VO service from scratch. On the other hand, to serve as a community-building exercise in which SVO staff and data providers know each other, data centres describe their needs and VO staff explains what the Virtual Observatory can offer to cover those needs. The workshop program and corresponding presentations have been made available at the SVO website.

Moving forward with Data Standards

The past six months have seen the recommendation of three new data standards. These include a recommended syntax for writing the string representation of unit labels (“VOUnits”), and the introduction of the Parameter Description Language (PDL), which intends to be an expressive language for self-descriptive web services exposing the semantic nature of input and output parameters. With the goal of providing fast spatial comparisons between image coverage maps, the Multi-Order Coverage map specification reached version 1.0. This version is based on the HEALPix sky tessellation algorithm, which is one way to provide a hierarchically based spatial index.

VO applications and implementation highlights

Argentina Virtual Observatory’s Data Center

The Argentina Virtual Observatory, NOVA, announces the release of its new database, powered by the GAVO DACHs technology. Data can be queried through specific forms at the NOVA web pages or through any VO tool such as Aladin, SPLAT, TOPCAT, etc. The database will be fed with material collected by Argentinian astronomers, and it is expected to grow rapidly in the following months. Currently, the NOVA database includes a JHKs merged catalogue from the first data release of the ESO public survey of the Milky Way bulge and southern plane named ‘‘VISTA variables in the Vía Láctea’’ (VVV; Saito et al 2012)..

More Information: http://nova.iafe.uba.ar

Stat-Lite - an Android Application

VO-India has recently launched Stat-Lite - an Android application that provides an interactive and easy introduction to the concepts of Descriptive Statistics and Curve Plotting. It includes basic features like loading VOTable and ASCII formatted datasets and performing some basic statistical analysis such as correlation tests, summary statistics, etc. Some of the novel features of this application include graphs with multi-touch gesture support allowing the user to pan and zoom to study specific areas, and the ability to study the effect of outliers on regression fits by adding them using a simple interface. The interface and content has been designed for high-school and undergraduate students. It uses ‘Apache Commons Math’ library for statistical calculations and a third party charting API called ‘AChartEngine’ for rendering graphs. The curve plotting module, apart from having all the major categories of pre-defined functions, has the ability to plot any arbitrary mathematical function by writing it down as a combination of the functions in the existing library. The prime motivation of this development was making useful software available on low-cost Aakash (Sky) Android tablets being made available to students in India.

More Information: http://vo.iucaa.ernet.in/~voi/voandroidsl.html

Upgrades to the US VAO registry at STScI

The VAO project has upgraded their service registry hosted at STScI, including major underlying database changes to support evolving IVOA standard search interfaces and familiar client tools including TOPCAT. Curation efforts are ongoing, and the database migration includes the removal of many inactive services across the IVOA from the registry holdings, leading to better search results. A formal release with documentation and available code will be part of the VAO closeout, as will a functional ‘wizard’-like form-based interface for data service curators to maintain their own registered information. A RegTAP service based on this upgrade is in progress.

More Information: http://vao.stsci.edu/directory/ is the main user-facing search; service interfaces and further information is listed there under ‘Developers’

TOPCAT and CDS X-Match

TOPCAT now provides integrated access to CDS’s excellent X-Match service. This means you can easily take a table loaded in TOPCAT and crossmatch it on sky position against any of the tables in the VizieR or Simbad databases, covering almost all published astronomical catalogues. It does the same job as TOPCAT’s old multi-cone function, but is much, much faster, typically around a million rows a minute. A similar function is also available from the command line using STILTS. These matches impose no limit on table size.

More Information: http://www.starlink.ac.uk/topcat/

US VAO Data Discovery Tool: Version 1.7 released

The US VAO released a new version of the Data Discovery Tool (v1.7) on August 25, 2014. With this tool you can find datasets from thousands of astronomical collections known to the VO and over wide areas of the sky, including thousands of astronomical collections — photometric catalogs and images — and archives around the world. New features of the Data Discovery Tool include: direct search of the Mikulski Archive for Space Telescopes (MAST), crossmatch search results with the major CDS catalogs via their X-Match service, or with MAST archive observations, and upload a target list into the tool for the purpose of crossmatching.

More Information: http://vao.stsci.edu/discover

Some recent papers about VO-enabled science

Orion revisited. II. The foreground population to Orion A
Bouy, H.; Alves, J.; Bertin, E.; Sarro, L. M.; Barrado, D
Astronomy & Astrophysics, Volume 564, id.A29, 12 pp. (2014).

Aims: Following the recent discovery of a large population of young stars in front of the Orion nebula, we carried out an observational campaign with the DECam wide-field camera covering ≈10 deg2 centered on NGC 1980 to confirm, probe the extent of, and characterize this foreground population of pre-main-sequence stars. Methods: We used multiwavelength wide-field images and catalogs to identify potential foreground pre-main-sequence stars using a novel probabilistic technique based on a careful selection of colors and luminosities. Results: We confirm the presence of a large foreground population towards the Orion A cloud. This population contains several distinct subgroups, including NGC 1980 and NGC 1981, and stretches across several degrees in front of the Orion A cloud. By comparing the location of their sequence in various color-magnitude diagrams with other clusters, we found a distance and an age of 380 pc and 5 ~ 10 Myr, in good agreement with previous estimates. Our final sample includes 2123 candidate members and is complete from below the hydrogen-burning limit to about 0.3 M⊙, where the data start to be limited by saturation. Extrapolating the mass function to the high masses, we estimate a total number of ≈2600 members in the surveyed region. Conclusions: We confirm the presence of a rich, contiguous, and essentially coeval population of about 2600 foreground stars in front of the Orion A cloud, loosely clustered around NGC 1980, NGC 1981, and a new group in the foreground of the OMC-2/3. For the area of the cloud surveyed, this result implies that there are more young stars in the foreground population than young stars inside the cloud. Assuming a normal initial mass function, we estimate that between one to a few supernovae must have exploded in the foreground population in the past few million years, close to the surface of Orion A, which might be responsible, together with stellar winds, for the structure and star formation activity in these clouds. This long-overlooked foreground stellar population is of great significance, calling for a revision of the star formation history in this region of the Galaxy.

Refereed Publications

The ADS query we manually curate for the bibliography in this newletter.

All ADS links mentioning the “virtual observatory” in the abstract.

All refereed publications mentioning the “virtual observatory” in the abstract.

New VO tutorials or outreach materials

Using Virtual Observatory with Python: querying remote astronomical databases

This tutorial is devoted to extending an existing catalogue with data taken elsewhere, either from CDS Vizier or Simbad database. As an example, we used the so-called ‘Spectroscopic Survey of Stars in the Solar Neighborhood’ (aka. S4N, Allende Prieto et al. 2004) in order to retrieve all objects with available data for the set of fundamental stellar parameters effective temperature, surface gravity and metallicity. Then for each object in this dataset we query Simbad database to retrieve the projected rotational velocity. This combines Vizier and Simbad queries made using Python astroquery module. The tutorial covers remote database access, filtering tables with arbitrary criteria, creating and writing your own tables, and basics of plotting in Python.

More information: http://arxiv.org/abs/1408.7026 and tutorial webpage

VO calendar

About the IVOA
For Astronomers
For Developers
For Members