IVOA Newsletter - September 2013 (pdf)

Created: August 31, 2013 - 22:01 UTC

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IVOA Newsletter Editors: Mark G. Allen, Deborah Baines, Sarah Emery Bunn, Chenzou Cui, 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, 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

South Africa’s Astronomical Agreement for Big Data

The South African National Research Foundation’s three astronomical facilities have formed the South African Astroinformatics Alliance (SA3 pronounced “SA cubed”), which serves as a virtual observatory for the country. South Africa hosts new and upcoming observational facilities that will generate huge amounts of data including the Southern African Large Telescope (SALT), the Karoo Array Telescope (MeerKAT) and a large part of the SKA. See the SA3 announcement of their “Astronomical agreement signed for big data!”. SA3 is a member of the IVOA since October 2012.

News from VObs.it: Remote Telescope networks for schools: toward publishing educational data in VO

The European Hands-On-Universe Milky Way (EUHOUMW) is an educational project funded by the European Commission to bring real radio observations into classrooms, where participating students use five remotely controlled educational radio telescopes. EUHOUMW is now evaluating how to publish the collected radio data in VO format to enable data sharing (e.g. with the Italian optical robotic telescope network), to simplify data management of multi-classroom projects, and to more easily incorporate professional data in education projects. An unofficial kick-off of the collaboration between EUHOUMW and VO was held in Paris, September 5-6, 2013. The topics being addressed included; how to tag education data alongside professional data in the VO, and the use of “educationalized” VO tools (following educational use of Aladin and Stellarium). Publishing, archiving, and maintaining educational data are topics for the September 2013 IVOA Interoperability and ADASS meetings.

VO applications and implementation highlights

ALMA VO Service

The Japanese Virtual Observatory (JVO) and ALMA-J teams have opened a VO-based data distribution system for ALMA data cubes. The aim is to help users access public ALMA data without huge data transfers. Two user applications, ALMAWebQL and Vissage, were developed for this system. ALMAWebQL is a component of the JVO Portal and enables the user to visualize and make cut-outs of ALMA data cubes in a web browser, while Vissage is a desktop application to visualize downloaded ALMA data cubes in more detail.

More Information: http://jvo.nao.ac.jp/news/alma-vo/index.html

TheoSSA

The TheoSSA (Theoretical Stellar Spectra Access) service provides access to synthetic spectral energy distributions (SEDs) that may be calculated by any model-atmosphere code. The database contains pre-calculated SEDs over a wide range of effective temperature, surface gravity, and elemental composition. The related TMAW tool allows the calculation of individual SEDs that presently can consider opacities of the elements H, He, C, N, O, Ne, Na, and Mg.

More Information: http://dc.g-vo.org/theossa

TIRO

The TIRO (Tuebingen IRon Opacity) service constructs model atoms of Ca, Sc, Ti, V, Cr, Mn, Fe, Co, and Ni based on Kurucz’ atomic data using a statistical approach (introducing super-levels and super-lines) and calculates the respective bound-bound and bound-free absorption cross-section.

More information: http://astro.uni-tuebingen.de/~TIRO

Iris version 2.0

The US VAO has released Iris 2.0, the latest version of the spectral energy distribution (SED) analysis tool. Iris comes with powerful new science capabilities which allow the redshifting, interpolation and smoothing of SEDs, and measurement of integrated fluxes through simple spectral bandpasses or through one of the thousands of photometric filters provided by the Spanish VO Filter Profile Service. Users can also apply simple aperture corrections to individual photometric points or to whole SED segments. In addition to improved visualization capabilities, including the co-plotting of SEDs, Iris 2.0 has increased interoperability with other VO tools. You can watch Iris in action in this video tutorial.

More information: http://www.usvao.org/science-tools-services/iris-sed-analysis-tool/

Some recent papers about VO-enabled science

The virtual observatory service TheoSSA: Establishing a database of synthetic stellar flux standards. I. NLTE spectral analysis of the DA-type white dwarf G 191-B2B

Rauch, T.; Bohlin, R.; Kruk, J. W.; Werner, K. Astronomy & Astrophysics, in press

H-rich, DA-type white dwarfs are particularly suited as primary standard stars for flux calibration. State-of-the-art NLTE models consider opacities of species up to trans-iron elements and provide reliable synthetic stellar-atmosphere spectra to compare with observation. We establish a database of theoretical spectra of stellar flux standards that are easily accessible via a web interface. In the framework of the Virtual Observatory, the German Astrophysical Virtual Observatory developed the registered service TheoSSA. It provides easy access to stellar spectral energy distributions (SEDs) and is intended to ingest SEDs calculated by any model-atmosphere code. In case of the DA white dwarf G 191-B2B, we demonstrate that the model reproduces not only its overall continuum shape but also the numerous metal lines exhibited in its ultraviolet spectrum. TheoSSA is in operation and contains presently a variety of SEDs for DA white dwarfs. It will be extended in the near future and can host SEDs of all primary and secondary flux standards. The spectral analysis of G 191-B2B has shown that our hydrostatic models reproduce the observations best at an effective temperature of 60000 +/- 2000K and a surface gravity of log g = 7.60 +/- 0.05. We newly identified Fe VI, Ni VI, and Zn IV lines. For the first time, we determined the photospheric zinc abundance with a logarithmic mass fraction of -4.89 (7.5 times solar). The abundances of He (upper limit), C, N, O, Al, Si, O, P, S, Fe, Ni, Ge, and Sn were precisely determined. Upper abundance limits of 10% solar were derived for Ti, Cr, Mn, and Co. The TheoSSA database of theoretical SEDs of stellar flux standards guarantees that the flux calibration of all astronomical data and cross-calibration between different instruments can be based on the same models and SEDs calculated with different model-atmosphere codes and are easy to compare.

Refereed Publications

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

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

VO calendar

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