International Virtual Observatory Alliance Research Articles

TSCat: data model and storage engine for AI-based light-curve analysis

ABSTRACT Light-curve data are one of the most important data sources in time domain astronomy research. With the advancement of observation facilities and the continuous accumulation of observation data, and considering the analysis needs of large sample data sets, software or tools based on new technologies, especially artificial intelligence (AI), will be indispensable for light-curve analysis. The light-curve analysis tool designed by an individual will follow its own defined data structure, which will make the tools designed and developed by different individuals incompatible. A unified light-curve data model will be able to solve this compatibility problem, similar to the traditional flexible image transport system (FITS) file format. This paper proposes a light-curve data model named TSCat, designs and implements a data storage engine. The TSCat data model defines the basic metadata and format required for storing optical curve data following the international virtual observatory alliance (IVOA) data format specification system. The TSCat storage engine implements basic operations such as importing, storing, and accessing light-curve data. The function and performance of the TSCat storage engine are evaluated through the actual observation data. The experimental results show that the TSCat data model is complete enough to support the analysis of light curves. TSCat will help support the standardization of the data access level of software and tools in the field of light-curve analysis, and provide a new reference for the specification system of astronomical scientific data formats.

DOI in the IVOA: the VizieR implementation example

DOIs (Digital Object Identifiers) have become essential in the scientific landscape for data citation and preservation. DOI design follows open data requirements: they are fully integrated in the Web architecture, and they provide a canvas of documented resources that can be linked by cross references. The key to success is the DOI metadata description and its documentation that improves the data visibility and citation. In this context, members of the Data Curation and Preservation (DCP) Interest Group of the International Virtual Observatory Alliance (IVOA) worked together to identify the state of the art of different aspects of the DOI in operation in astronomy. This state of the art shows different aspects for several types of data in the landscape - for example, the VizieR catalogue service of the Strasbourg Astronomical Data Center (CDS) provides DOIs for catalogues (tables and associated data). We highlight the status of the IVOA Note, and give feedback from the DOI implemention experience in VizieR.

The data center construction of the Xinjiang Astronomical Observatory based on virtual observatory standards

As part of the Chinese National Astronomical Data Center, the Xinjiang Astronomical Observatory Data Center is built based on the virtual observatory standards. The data resources mainly include the pulsar dataset, the molecular spectral lines dataset, the intra-day variability source dataset generated by the Nanshan 25 m radio telescope, and the Nanshan 1 m wide-field telescope dataset, published through about a dozen data services, including a Table Access Protocol (TAP) endpoint. Some of these data services are registered with the International Virtual Observatory Alliance. Users can use standard virtual observatory tools, browsers, and scripts to retrieve all the metadata information in the data center and to realize simple data analysis, processing, and visualization operations.

GWOPS: A VO-technology Driven Tool to Search for the Electromagnetic Counterpart of Gravitational Wave Event

The search and follow-up observation of electromagnetic (EM) counterparts of gravitational waves (GW) is a current hot topic of GW cosmology. Due to the limitation of the accuracy of the GW observation facility at this stage, we can only get a rough sky-localization region for the GW event, and the typical area of the region is between 200 and 1500 square degrees. Since GW events occur in or near galaxies, limiting the observation target to galaxies can significantly speedup searching for EM counterparts. Therefore, how to efficiently select host galaxy candidates in such a large GW localization region, how to arrange the observation sequence, and how to efficiently identify the GW source from observational data are the problems that need to be solved. International Virtual Observatory Alliance has developed a series of technical standards for data retrieval, interoperability and visualization. Based on the application of VO technologies, we construct the GW follow-up Observation Planning System (GWOPS). It consists of three parts: a pipeline to select host candidates of GW and sort their priorities for follow-up observation, an identification module to find the transient from follow-up observation data, and a visualization module to display GW-related data. GWOPS can rapidly respond to GW events. With GWOPS, the operations such as follow-up observation planning, data storage, data visualization, and transient identification can be efficiently coordinated, which will promote the success searching rate for GWs EM counterparts.

Towards an astronomical science platform: Experiences and lessons learned from Chinese Virtual Observatory

In the era of big data astronomy, next generation telescopes and large sky surveys produce data sets at the TB or even PB level. Due to their large data volumes, these astronomical data sets are extremely difficult to transfer and analyze using personal computers or small clusters. In order to offer better access to data, data centers now generally provide online science platforms that enable analysis close to the data. The Chinese Virtual Observatory (China-VO) is one of the member projects in the International Virtual Observatory Alliance and it is dedicated to providing a research and education environment where globally distributed astronomy archives are simple to find, access, and interoperate. In this study, we summarize highlights of the work conducted at the China-VO, as well the experiences and lessons learned during the full life-cycle management of astronomical data. Finally, We discuss the challenges and future trends for astronomical science platforms.

IVOA HiPS implementation in the framework of WorldWide Telescope

Abstract The WorldWide Telescope(WWT) is a scientific visualization platform which can browse deep space images, star catalogs, and planetary remote sensing data from different observation facilities in a three-dimensional virtual scene. First launched and then open-sourced by Microsoft Research, the WWT is now managed by the American Astronomical Society (AAS). Hierarchical Progressive Survey (HiPS) is an astronomical data release scheme proposed by Centre de Donnees astronomiques de Strasbourg (CDS) and has been accepted as a recommendation by International Virtual Observatory Alliance (IVOA). The HiPS solution has been adopted widely by many astronomical institutions for data release. Since WWT selected Hierarchical Triangular Mesh (HTM) as the standard for data visualization in the early stage of development, data released by HiPS cannot be visualized in WWT, which significantly limits the application of WWT. This paper introduces the implementation method for HiPS dataset visualization in WWT, and introduces HiPS data projection, mesh rendering, and data index implementation in WWT. Taking Chang’E-2 lunar probe data as an example, this paper introduces how to convert planetary remote sensing data into a HiPS dataset and integrate it into WWT. This paper also compares the efficiency and memory consumption of WWT loading its native data and HiPS data, and illustrates the application of HiPS in scientific data visualization and science education in WWT.

Armenian Astronomical Heritage and Big Data

AbstractAstronomy in Armenia was popular since ancient times and Armenia is rich in its astronomical heritage, such as ancient and medieval Armenian calendars, records of astronomical events by ancient Armenians, the astronomical heritage of the Armenian medieval great thinker Anania Shirakatsi, etc. Armenian astronomical archives have accumulated vast number of photographic plates, films and other careers of observational data. The Digitized Markarian Survey or the First Byurakan Survey, is the most important low-dispersion spectroscopic database. It is one of the rare science items included in UNESCO “Memory of the World” Documentary Heritage list. The Byurakan Astrophysical Observatory (BAO) Plate Archive Project (2015–2021) will result in digitization and storage of some 37,000 astronomical plates and films and in creation of an Electronic Database for further research projects. Based on these data and archives and development of their interoperability, the Armenian Virtual Observatory was created and joined the International Virtual Observatory Alliance.

The XinJiang Astronomical Observatory NSRT Pulsar Data Archive

The sensitivity of our pulsar observation system with typical integration time of 16 minutes has reached 0.4 mJy after we have upgraded the receiver cooling system of NanShan 25-m radio telescope (NSRT) at Xinjiang Astronomical Observatory (XAO) in 2002. About 280 pulsars were observed after the upgrade. The NanShan station pulsar data is transmitted to the data center at XAO headquarters via a 300Mb/s dedicated data link for long-term storage, and the remote backup is realized by synchronous data transmission between NanShan station and XAO headquarters. Metadata extraction, archiving, and releasing are completed by the data release servers which are located in XAO headquarters. At present, more than 84000 pulsar observation data files in the PSRFITS format have been released with a maximum file size of 1GB. XAO pulsar data online service provides cone search and multiobject constraint query. We have published our data based on Virtual Observatory (VO) standards. The online pulsar data service is registered in the International Virtual Observatory Alliance’s Registry. Users can access the data through common VO tools.

Space Activities in Armenia: past, present and future

A review about Space related activities in Armenia is given, particularly in the Byurakan Astrophysical Observatory (BAO, Armenia), including the first Space Astronomy projects by Grigor Gurzadian in 1960s-1970s (Orion and Orion-2 UV observatories), research projects with USA (NASA) and European (ESA) Space observatories (IRAS, ROSAT, Hubble, Spitzer, WISE, etc.) by BAO scientists, Armenian participation in International Virtual Observatory Alliance (IVOA), International Planetary Data Alliance (IPDA), and UN Committee on the Peaceful Users of the Outer Space (COPUOS), “Roscosmos” station in Byurakan established in 2014 for monitoring of Space debris, Armenian participation in NASA Space Apps Hackathons, Armenian participation in the European H2020 project, including the Space field, organization of Space related meetings and schools in Byurakan, etc. Armenia with its astronomical and other related background has great potential in establishing collaborations and promoting Space Sciences and Space Technologies.

Data as a research infrastructure CDS, the Virtual Observatory, astronomy, and beyond

The situation of data sharing in astronomy is positioned in the current general context of a political push towards, and rapid development of, scientific data sharing. Data is already one of the major infrastructures of astronomy, thanks to the data and service providers and to the International Virtual Observatory Alliance (IVOA). Other disciplines are moving on in the same direction. International organisations, in particular the Research Data Alliance (RDA), are developing building blocks and bridges to enable scientific data sharing across borders. The liaisons between RDA and astronomy, and RDA activities relevant to the librarian community, are discussed.

Interoperability in planetary research for geospatial data analysis

For more than a decade there has been a push in the planetary science community to support interoperable methods for accessing and working with geospatial data. Common geospatial data products for planetary research include image mosaics, digital elevation or terrain models, geologic maps, geographic location databases (e.g., craters, volcanoes) or any data that can be tied to the surface of a planetary body (including moons, comets or asteroids). Several U.S. and international cartographic research institutions have converged on mapping standards that embrace standardized geospatial image formats, geologic mapping conventions, U.S. Federal Geographic Data Committee (FGDC) cartographic and metadata standards, and notably on-line mapping services as defined by the Open Geospatial Consortium (OGC). The latter includes defined standards such as the OGC Web Mapping Services (simple image maps), Web Map Tile Services (cached image tiles), Web Feature Services (feature streaming), Web Coverage Services (rich scientific data streaming), and Catalog Services for the Web (data searching and discoverability). While these standards were developed for application to Earth-based data, they can be just as valuable for planetary domain. Another initiative, called VESPA (Virtual European Solar and Planetary Access), will marry several of the above geoscience standards and astronomy-based standards as defined by International Virtual Observatory Alliance (IVOA). This work outlines the current state of interoperability initiatives in use or in the process of being researched within the planetary geospatial community.

The igmspec database of public spectra probing the intergalactic medium

Abstract We describe v02 of igmspec, a database of publicly available ultraviolet, optical, and near-infrared spectra that probe the intergalactic medium (IGM). This database, a child of the specdb repository in the specdb github organization, comprises 403 277 unique sources and 434 686 spectra obtained with the world’s greatest observatories. All of these data are distributed in a single ≈ 25 GB HDF5 file maintained at the University of California Observatories and the University of California, Santa Cruz. The specdb software package includes Python scripts and modules for searching the source catalog and spectral datasets, and software links to the linetools package for spectral analysis. The repository also includes software to generate private spectral datasets that are compliant with International Virtual Observatory Alliance (IVOA) protocols and a Python-based interface for IVOA Simple Spectral Access queries. Future versions of igmspec will ingest other sources (e.g. gamma-ray burst afterglows) and other surveys as they become publicly available. The overall goal is to include every spectrum that effectively probes the IGM. Future databases of specdb may include publicly available galaxy spectra (exgalspec) and published supernovae spectra (snspec). The community is encouraged to join the effort on github: https://github.com/specdb .

Armenian virtual observatory simple image access service

Abstract The aim of the article is to introduce the data sharing service of the Armenian Virtual Observatory (ArVO) based on the Simple Image Access (SIA) Protocol of the International Virtual Observatory Alliance (IVOA).

Indexing data cubes for content-based searches in radio astronomy

Abstract Methods for observing space have changed profoundly in the past few decades. The methods needed to detect and record astronomical objects have shifted from conventional observations in the optical range to more sophisticated methods which permit the detection of not only the shape of an object but also the velocity and frequency of emissions in the millimeter-scale wavelength range and the chemical substances from which they originate. The consolidation of radio astronomy through a range of global-scale projects such as the Very Long Baseline Array (VLBA) and the Atacama Large Millimeter/submillimeter Array (ALMA) reinforces the need to develop better methods of data processing that can automatically detect regions of interest (ROIs) within data cubes (position–position–velocity), index them and facilitate subsequent searches via methods based on queries using spatial coordinates and/or velocity ranges. In this article, we present the development of an automatic system for indexing ROIs in data cubes that is capable of automatically detecting and recording ROIs while reducing the necessary storage space. The system is able to process data cubes containing megabytes of data in fractions of a second without human supervision, thus allowing it to be incorporated into a production line for displaying objects in a virtual observatory. We conducted a set of comprehensive experiments to illustrate how our system works. As a result, an index of 3% of the input size was stored in a spatial database, representing a compression ratio equal to 33:1 over an input of 20.875 GB, achieving an index of 773 MB approximately. On the other hand, a single query can be evaluated over our system in a fraction of second, showing that the indexing step works as a shock-absorber of the computational time involved in data cube processing. The system forms part of the Chilean Virtual Observatory (ChiVO), an initiative which belongs to the International Virtual Observatory Alliance (IVOA) that seeks to provide the capability of content-based searches on data cubes to the astronomical community.

The Virtual Astronomical Observatory: Re-engineering access to astronomical data

The U.S. Virtual Astronomical Observatory was a software infrastructure and development project designed both to begin the establishment of an operational Virtual Observatory (VO) and to provide the U.S. coordination with the international VO effort. The concept of the VO is to provide the means by which an astronomer is able to discover, access, and process data seamlessly, regardless of its physical location. This paper describes the origins of the VAO, including the predecessor efforts within the U.S. National Virtual Observatory, and summarizes its main accomplishments. These accomplishments include the development of both scripting toolkits that allow scientists to incorporate VO data directly into their reduction and analysis environments and high-level science applications for data discovery, integration, analysis, and catalog cross-comparison. Working with the international community, and based on the experience from the software development, the VAO was a major contributor to international standards within the International Virtual Observatory Alliance. The VAO also demonstrated how an operational virtual observatory could be deployed, providing a robust operational environment in which VO services worldwide were routinely checked for aliveness and compliance with international standards. Finally, the VAO engaged in community outreach, developing a comprehensive web site with on-line tutorials, announcements, links to both U.S. and internationally developed tools and services, and exhibits and hands-on training .... All digital products of the VAO Project, including software, documentation, and tutorials, are stored in a repository for community access. The enduring legacy of the VAO is an increasing expectation that new telescopes and facilities incorporate VO capabilities during the design of their data management systems.

A brief survey on the Virtual Observatory

This paper presents a short survey on the astronomical Virtual Observatories (VOs) that are part of the International Virtual Observatory Alliance (IVOA). From how they are distributed worldwide to their specialization range on the electromagnetic spectrum, we summarize key aspects of the current 21 VO members. Through the registry service, we explore the resources that the VO offer as a whole, and identify that even though the VO is already a mature initiative, there are important challenges to address in the near future.

VObs.it, the Italian contribution to the international Virtual Observatory—History, activities, strategy

Abstract The origins of the Italian contribution to the international Virtual Observatory (VO) were mainly tied to the definition and implementation of a Data Grid using Grid standards. From there on, by means of a step-wise evolution, activities started including the implementation of VO-aware tools and facilities, or the production of services accessing data archives in ways compliant to the international VO standards. An important activity the Italian VO community has carried out is the dissemination of the VO capabilities to professionals, students and amateurs: in particular, an important and maybe unique success has been bringing to the classrooms the VO, and using it as a powerful tool to teach astronomy at all levels, from junior high school to undergraduate courses. Lately, there has been also direct involvement of the Italian community in the definition of standards and services within the framework of the International Virtual Observatory Alliance (IVOA), and participation and leadership in the IVOA Working Groups. Along this path, the national funding for these activities has been rather low, although essential to carry the activities on. There were no bursts of funding to allow a quick rise in activities leading to the fast realisation of tools and systems. Rather, the manpower involved in VObs.it has been always fairly low but steady. In the view of managing a national VO initiative with a low budget, strategic choices were made to exploit the available resources and to guarantee a constant background activity, mainly geared at providing services to the community, development in lower-priority VO areas, dissemination and support.

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.

VADMC: The Infrastructure

Abstract The Virtual Atomic and Molecular Data Centre (VAMDC; http://www.vamdc.eu) is a European-Union-funded collaboration between several groups involved in the generation, evaluation, and use of atomic and molecular data. VAMDC aims at building a secure, documented, flexible and interoperable e-Science environment-based interface to existing atomic and molecular databases. The global infrastructure of this project uses technologies derived from the International Virtual Observatory Alliance (IVOA). The infrastructure, as well as the first database prototypes will be described.

Science Initiatives of the US Virtual Astronomical Observatory

Abstract The United States Virtual Astronomical Observatory program is the operational facility successor to the National Virtual Observatory development project. The primary goal of the US VAO is to build on the standards, protocols, and associated infrastructure developed by NVO and the International Virtual Observatory Alliance partners and to bring to fruition a suite of applications and web-based tools that greatly enhance the research productivity of professional astronomers. To this end, and guided by the advice of our Science Council (advisory committee), we are focusing on five science initiatives in the first two years of VAO operations: (1) scalable cross-comparisons between astronomical source catalogs, (2) dynamic spectral energy distribution construction, visualization, and model fitting, (3) integration and periodogram analysis of time series data from the Harvard Time Series Center and NASA Star and Exoplanet Database, (4) integration of VO data discovery and access tools into the IR AF data analysis environment, and (5) a web-based portal to VO data discovery, access, and display tools. We are also developing tools for data linking and semantic discovery, and have a plan for providing data mining and advanced statistical analysis resources for VAO users. Initial versions of these applications and web-based services are being released over the course of the summer and fall of 2011, with further updates and enhancements planned for throughout 2012 and beyond.