News & Announcements

NVO Book Published

"The National Virtual Observatory: Tools and Techniques for Astronomical Research", has been published as an ASP Conference Series (Volume No. 382) and is available to order at the ASP website. This volume is a collection of the NVO Summer School lectures and tutorials. It includes a complete set of software libraries and worked examples to guide the astronomer/software developer through the process of developing VO-enabled programs in a variety of programming languages and scripting environments. It is an essential guide for those interested in combining data from diverse and distributed astronomical data collections, for accessing large astronomical survey databases, and for making available to the research community one's own data collections and catalogs. In addition, the introductory material describes the origin of the Virtual Observatory and its potential role in astronomical research. Several chapters are also included that describe research results obtained by participants in the NVO Summer Schools using VO tools and technologies. This book is suitable for astronomers and students of astronomy at the undergraduate and graduate level who have an interest in using computers and the Internet to optimize and extend their research. It would also be of interest to researchers and software professionals working in related fields where access to distributed data collections is becoming essential.

2008 NVO Summer School

The 4th NVO Summer School will be held 3-11 September 2008 in Santa Fe, NM. In this nine-day, hands-on summer school, participants will work with experienced NVO users and software specialists to become familiar with how to discover, access, visualize, and analyze data with the Virtual Observatory. Those attending will be introduced to VO tools and utilities by using them to accomplish a variety of research goals. Some of the research tasks that will be addressed include data mining, multiwavelength analysis, and temporal astronomy. In the latter part of the summer school, small teams will pursue their own VO-enabled projects.

The application form will be available on the summer school website after April 15. Anyone interested in learning how to use the VO for astronomical research is welcome to apply. There will also be sessions for those interested in exposing data through VO protocols. We encourage scientists at any stage of their career, graduate student to tenured professor, to apply. Programming experience in Python or Java is strongly advised. Space and budgetary constraints limit participation to 40 people. Applications will be reviewed by the organizing committee and participants will be informed by July 1, 2008 of their acceptance to the Summer School.

There will be a $500 registration fee for participants. If this presents a financial hardship that would preclude attendance, applicants may request a waiver of the fee. The organizing committee will review such requests on a case by case basis. Upon acceptance to the Summer School, the fee will be due by August 1. Accommodations are provided for all participants. In addition, a travel stipend of up to $400 and a per diem stipend of $225 are available for successful applicants from US institutions who can commit to attending the entire course and who do not have funds available to cover these expenses.

The NVO Summer School is made possible through the support of the National Science Foundation and the National Aeronautics and Space Administration. Questions about the summer school should be directed to .

NVO Inside

What is NVO Inside?

An emerging theme in the Virtual Observatory is "NVO Inside"—the idea that VO protocols are more prevalent than might be apparent on the surface. Think of the person who says "I don't need NASA satellites to tell me the weather, I just tune into the Weather Channel," with no idea that the data driving that channel comes from those satellites!

One way in which NVO has become pervasive is through a format for representing tables, called VOTable. It is based on FITS tables, but has the advantage that it can carry richer metadata: about the data in the table, about the provenance and description of the table. VOTable is scalable to handle bulk data. VOTable is used for catalog data, which is the traditional list of astronomical objects and quantitative attributes; but it is also used in the VO for metadata, or "data about data". When querying a VO service for images or spectra, it is a two-stage process: the response to the query is not the images and spectra themselves, but rather a VOTable describing them, including links to the actual FITS data files.

NVO and its international partners have worked with most of the big data centers (HEASARC, IPAC, STScI, CDS, ESO, etc) to make their outputs available in the VOTable format, and they have built tools that visualize and manipulate VOTable. Therefore a teacher or astronomer can now get VOTable from a data center, a query of any of thousands of catalogs with complex constraints, then understand and visualize the results, all with portable, open-source software.

Some examples of organizations with NVO Inside are:

NED and Simbad: Many services that produce VOTable
Google: Reports VOEvents in "Sky in Google Earth" product
Microsoft Research: Using VO protocols in 'Worldwide Telescope' product
Lockheed-Martin: Using VOEvent format for Sun-orbiting solar observatory
NASA data centers: Most support VOTable, including HEASARC andIPAC
LSST (Large Synoptic Survey Telescope): Will use VOEvent protocol for event distribution
SDSS (Sloan Digital Sky Survey): Fully supports VO protocols
2MASS (Two Micron All Sky Survey): Fully supports VO protocols
NOAO (National Optical Astronomy Observatories): Fully supports VO protocols

Is your organization or project NVO Inside? Please let us know!

Google Sky

Astronomy has always been one of the most visual of the sciences, but with the growing size of astronomical surveys, how we browse and interact with imagery covering the full sky and at many different wavelengths has become a significant challenge. On August 22nd of last year Google introduced a new feature to Google Earth; Sky in Google Earth (aka Google Sky) that addresses the challenge of exploring Terabytes of imaging data through the use of efficient streaming technologies. Google Sky combines all-sky imagery, common astronomical catalogs, catalog and positional searches, the capacity to annotate images and share these annotations with other users, and the ability to display time domain data (from the motion of the planets to time series of images of variable sources) in a single interface that runs natively on all major platforms. It provides an interactive visualization platform that can be tailored to a wide range of needs from research scientists to amateur astronomers to the public as a whole.

To run Google Sky, download the latest Google Earth client from http://earth.google.com and start it up; click the Saturn icon on the top tool bar and the view will switch to the sky overhead. Figure 1 shows the layout of Sky; the left panel displays the default layers that are available as well as any other layers you may have created or downloaded. The search bar above the layers can be used to find objects by name or position on the sky. Clicking on marked objects displays Wikipedia information and links to Google Scholar, ADS, NED, SIMBAD, and other information sources. Documentation on how to use Google Sky can be found here.

The initial release of Google Sky focused on an optical view of the sky: combining images from the Sloan Digital Sky Survey, the photographic plates from the Digitized Sky Survey, and select images from the Hubble Space Telescope. Together these images provided a seamless view of the sky that can display an incredible dynamic range from the Milky Way through to images of the Hubble Ultra Deep Field. With an update that was released at the AAS in January 2008, Google Sky has expanded its range to include X-ray data from Chandra, ultraviolet images from GALEX, and infrared images from Spitzer (Figure 2 shows the image from Spitzer of NGC 3627), as well as all-sky surveys of the infrared and microwave sky from the IRAS and WMAP satellites. Beyond the sky observed by modern astronomers, Sky also incorporates a view of the historical sky from the celestial globes of Hevelius and Cassini. Dating back to the 16th and 17th centuries, it is remarkable to see how their drawings of the sky still influence our view of the constellations. For a more modern perspective, the embedded podcasts from Earth and Sky tell us about events that can be found in the sky over the coming months. Of particular interest to the VO communities, the VOEvent layer streams events from the Gamma Ray Network and current microlensing and supernovae surveys in real time—as each new event occurs it is displayed directly on Sky enabling follow-up by both amateur and professional astronomers alike.

While Google Sky provides many different views of the sky, it was designed to be an extensible environment that can both ingest and display a wide range of astronomical data. This means that, from its inception, Sky can be used to upload images and catalogs and share them with other researchers or with the public as a whole. The structure that makes this possible is a markup language used to place objects on the sky. The Keyhole Markup Language (KML) is a standard that references objects to the sky through the use of simple tags (e.g. coordinate tags to position an object, and description tags). Documentation for how to use KML for Sky can be found here, and there are many examples of its use at the Google Sky Gallery accessed through the "Add Content" button found above the layers panel of the application. In terms of extending Sky, one of the most interesting features available through KML is the "Network Link". A Network Link loads a file in response to an action by a user (such as changing the field of view or after a specified time interval). The file loaded can be generated dynamically which means that the network link can utilize scripts to return data. In astronomical applications this functionality has been used to query databases to identify objects within the field of view and to return images through an image access interface to dynamically overlay images as we browse around the sky. An example, from the AEGIS team, is shown in Figure 3 where network links are used to create a data browser for the AEGIS image and catalog server. Other example applications, such as a browser for the SDSS spectroscopic and photometric data can be found at the repository of Sky content at the University of Washington.

Many tools now exist to help users integrate their data with Sky. FITS images with valid coordinates can be easily converted into KML using the open source tool wcs2kml. This program takes in a FITS image, reprojects it to work with Sky, and generates the appropriate KML files. Publishing data with Sky is as simple as running the program and dropping the resulting files in a web accessible directory and notifying your collaborators, or uploading the link to the Google Sky Gallery or to the Google Sky Community. For large images there is an option in wcs2kml to create a pyramid of images at different resolutions, rather than a single image, which saves on network bandwidth requirements. For the command-line averse, staff at STScI have wrapped wcs2kml with a graphical interface which can be downloaded here.

There are many more features and ways to work with Google Sky than space permits in this article, and new features and data appear every few weeks in Sky. An example of this is the Google Maps interface to Sky that was released in December. This means that you can embed Sky in any browser and interact with it with all of the capabilities of Javascript, even on an iPhone.

Google is interested in feedback on new features, new data or new ways to look at the sky including any mashups you have created for discovering or displaying data on Google Sky; please contact Andrew Connolly (Univ. of Washington/Visiting Faculty at Google) at ajc[at]astro.washington.edu. It is hoped that Sky will provide the VO community with the ability to create, modify and share research and the excitement of research with a very broad community. Happy exploring.

Featured NVO Application

VO-CLI - Command Line Tools for the VO

VO-CLI is a package of command-line tools that provides familiar Unix-like access to VO services while hiding much of the complexity of the underlying VO framework from novice users. These tools can be used from the desktop or in scripting environments to build more complex desktop science applications, or for use in back-end CGI scripting to support web applications. Output tables are saved by default as comma-separated values making these easy to import into something like Excel; however, a variety of output table formats may be used (including Google Sky's KML format).

A key feature of the package is the ability to use familiar names for both objects and VO resources. A VO resource can be many different things, such as tools, catalogs, or web services. For example, a query for point-source data from 2MASS around NGC4256 will resolve the coordinates of the object automatically and you may refer to the catalog as '2mass-psc'. Most users will quickly learn these familiar resource names after spending a little time browsing the NVO Registry to find the primary resources they'll commonly use, but this name can also be used as a search term to expand a resource list to include, for example, any SDSS service. Two tasks exist to allow the user to experiment with the object and registry search functionality before querying for real data: The VOSESAME task can be used to convert object names to positions so that positions are resolved only once when repeatedly querying for data, and the VOREGISTRY task will allow you to browse the NVO Registry to locate a desired resource, verify the familiar name to use, find a more unique identifier, or simply browse for data services. Searches may be constrained by type of data or the bandpass used, and the search abilities can be used to create data queries that go beyond an astronomer's list of familiar primary resources.

The heart of the VO-CLI tasks is VODATA, which combines the other tasks' abilities to create and resolve resource and object lists with the query and retrieval of the actual data. VODATA will automatically parallelize large queries for efficiency, and flags permit the user to create queries for, e.g. "all HST image data" or "X-ray catalog data only". Image data may be accessed directly or downloaded later after a user has selected a desired subset of available data.

Typical usage of the VO-CLI tools falls into two categories: power-users who would call the tools from the shell prompt as they would any other command, e.g. to search the NVO Registry or retrieve data instead of using a traditional portal web page. The second use would be in a scripting environment, e.g. in building a small application that does some bit of science or interacts easily with other programs in the user's preferred environment. This might be a Python script or it could be an analysis environment like IRAF or IDL. The VO-CLI tools provide a fairly low-level interface to the VO; however, when used in scripts they provide a powerful way to retrieve VO data that can then be analyzed based on the science needs of the application. This ability becomes especially important for applications that need to combine VO data (e.g. large survey catalogs, reference data or multi-wavelength data) with data the user may already have on their desktop from more traditional observatories.

There is a VO-CLI introductory tour here. This page will lead you through examples of what each of the VO-CLI tools can do and allow you to run the application from the web-page directly. The documentation lists many examples, and with some practice a fairly sophisticated query can be created from the many available options.

Figure Caption: Image and catalog overlay of a region around M33 produced using VO-CLI tools to retrieve VO data and local script to render the display.

NVO Calendar

18-21 February , 2008 | Practical Semantic Astronomy Workshop | Pasadena, California
Workshop proceedings are posted at the website linked above.

7-11 April | Euro-VO Workshops: Theory in the VO & Grid and the VO | Garching, Germany
These workshops are organized in the framework of the EuroVO Data Center Alliance. They are organized back-to-back as there is a clear link between the two.

19-23 May, 2008 | IVOA Interoperability | Trieste, Italy
The IVOA Interop Meetings are aimed at making significant progress in generating new standards powering the development of the world wide Virtual Observatory initiatives.

3-11 September, 2008 | The 2008 NVO Summer School | Santa Fe, New Mexico
In this nine-day, hands-on summer school, participants will work with experienced NVO users and software specialists to become familiar with how to discover, access, visualize, and analyze data with the Virtual Observatory.

5-8 October 2008 | "Astronomical Data and the Virtual Observatory" session at CODATA21 | Kiev, Ukraine
Session Title: Managing Astronomical Data; Lessons learned in the development of virtual observatories. Call for Papers deadline March 31, 2008

27-31 October | IVOA Interoperability | Baltimore, Maryland
The IVOA Interop Meetings are aimed at making significant progress in generating new standards powering the development of the world wide Virtual Observatory initiatives.

2-5 November 2008 | ADASS XVIII | Quebec City, Canada
The Astronomical Data Analysis Software and Systems (ADASS) conference provides a forum for scientists and programmers concerned with algorithms, software and software systems employed in the acquisition, reduction, analysis, and dissemination of astronomical data.

Contact Information: Your feedback is important to us. To make sure we can address your questions and ideas, please send email to . You may also want to take a look at our Getting Started with NVO page to see if any of your questions are answered there.

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