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History of the Virtual Astronomical Observatory

Winds of Change

Astronomy has historically been a fragmented science. Astronomers would typically work alone or in small research groups to conduct observations of small, carefully selected samples (often with a priori prejudices) of objects in a limited part of the electromagnetic spectrum. Results were not always shared with the public and, if they were, they were shared passively without an active role from interested students, teachers, amateur astronomers, and the general public.

A paradigm shift

In the past decade, a paradigm shift has begun that will forever change how astronomical research is conducted and shared with the public. Astronomers are now increasingly working in large collaborations using survey telescopes or multiple telescopes covering a wide range of the electromagnetic spectrum.

Astronomers today have more data at their disposal than at any other time in history. This paradigm shift is occurring because of the following four main drivers of change:

More powerful telescopes

Larger and more sophisticated telescopes are able to take more high resolution images and spectra of the universe. Over the past couple of decades, a new type of telescope became popular, the survey telescope. These telescopes were not developed to target specific objects, but were instead developed to survey much of the sky. Astronomers could then look for specific objects or do a census of objects over much of the sky. Astronomy was now going to get statistically large samples of objects in the universe to study.

Current surveys include the Sloan Digital Sky Survey (SDSS), the Two Micron All Sky Survey (2MASS), the Massive Compact Halo Objects (MACHO), and the ROSAT All Sky Survey (RASS). The future Large Synoptic Survey Telescope (LSST — scheduled to begin science operations later this decade) will produce a wealth of data by repeatedly scanning the sky over a 10-year period. The LSST will not just produce a map of the universe, but will discover all sorts of objects that change between observations, giving us insight into whole new classes of variable objects.

Along with the advent of survey telescopes, astronomers are finally able to probe larger swaths of the electromagnetic spectrum with fleets of ground- and space-based telescopes. We now have telescopes observing the universe from high energy gamma rays, to visible light, down to low energy radio waves. Many of these telescopes are launched into space as a necessity; many types of light of the electromagnetic spectrum, such as gamma rays, X-rays, ultraviolet, and infrared light, cannot pass through Earth's atmosphere.

From these advances in telescope design, the general public now has access to multiwavelength images. Student projects are being developed to teach the power of using the full electromagnetic spectrum to study the universe. The sure amount of data from surveys and powerful telescopes allow anyone interested to become citizen scientists, who are helping astronomers classify objects in the universe, do population studies of objects in the universe, and even discover new objects.

Detectors that are larger, more sensitive to light,
and have higher resolution

While the mirrors or optics in telescopes act as giant light buckets collecting as much light as possible, the detectors capture that light for us to study.

In the earliest days of telescopic astronomy, astronomers could only use their eyes as detectors. If they wanted to show another person their discoveries, they had to draw what they saw by hand. This was obviously a very imprecise way to practice astronomy, and the eyes are only capable of detecting visible light.

By the late 19th century, photographic plates were used to capture the light gathered by telescopes. This was far superior to using eyes, since photographic plates could be exposed to incoming light for hours at a time, thus building up images of fainter objects. Photographic plates did have several disadvantages. They were heavy, difficult to process, and not as accurate as modern day detectors.

All of the new advances in telescope design are taking advantage of more advanced detectors that can accurately count individual photons of light.

Modern day detectors are called charge-coupled devices (CCDs) and are used in everything from common digital cameras to the most state-of-the-art telescope. Each CCD is made up of individual light-sensing pixels. The more individual pixels packed onto a given size of CCD, the better the resolution of the resulting image.

Higher resolution images are more clear and detailed. Lower resolution images appear increasingly blurry. Currently, the typical cameras purchased by a consumer have detectors with less than 20 million pixels. Astronomical-grade cameras use various types of detectors that can produce sharper images and capture larger swaths of the electromagnetic spectrum. As a comparison, the SDSS telescope has a 120-million-pixel detector. The future LSST will have a 3,200-million-pixel detector.

The higher resolution images produced by state-of-the-art astronomical-grade detectors are leading to a huge increase in data. Each individual pixel is actually data that must be recorded for analysis. These are producing incredibly detailed images in multiple wavelengths for the general public to admire. Amateur astronomers can purchase their own detectors for use on their backyard telescopes to create images that sometimes rival several ground-based research-level telescopes. Students also now have access to higher quality astronomical data.

Exponential growth of computing capability

The current technological explosion of telescope and detector capabilities is producing a huge amount of data. With this, we require more powerful computers to store and analyze the data. The SDSS, alone, is producing terabytes of data. The future LSST will produce more than 50 petabytes of data. One petabyte is equivalent to the amount of data obtained by all of CNN's news footage over five years.

Thankfully, computing capability has greatly increased, following the famous Moore's Law. Moore's Law states that computing power doubles every 18 months. This increase in computing power is critical to keep up with the increasing flow of data by detectors on telescopes. Incidentally, the rate of increase of the numbers of pixels on a CCD detector, or the quantity of data collected by that detector, also follows Moore's Law.

The growth of computer usage in homes and schools is providing the necessary infrastructure for the general public and students to study and use the astronomical data. Along with the advent of high-speed internet, as described below, the public now has the means to help carry out astronomical studies where large numbers of computers and/or users are required.

Expanding coverage and capacity of communication networks

Due to the increased computer power, along with the development of high-speed internet and broad internet coverage, astronomy is primed to take advantage of the wealth of astronomical data.

In 2002, it would take about 20 days to transfer one terabyte of data over the internet. In 2012, using an internet connection of 10 megabytes per second, it would take about 10 days to transfer one terabyte of data. With faster connection speeds, this can be reduced to a few days.

The speed of internet connections will continue to increase in the years ahead. With the spread of the internet, users can have nearly instantaneous access to the large data archives spread around the world. Users will also have access to internet cloud storage and online tools that help them analyze the data. This will create less reliance on having the absolute best computer in your home, office, or school.

These infrastructure gains will help pave the way for the discovery of new phenomena and previously undiscovered patterns in data, and will allow simultaneous access to astronomical data archives with access to images and spectra taken by the world's most powerful ground- and space-based telescopes. These gains will also allow broad access by anyone with internet access, and result in new learning and analysis tools.

The paradigm shift stokes discovery

There are several examples of how any combination of the above four key changes can influence astronomical discoveries.

Historical examples include the discovery of quasars when viewed using multiple portions of the electromagnetic spectrum (radio and visible light in this case). Extremely luminous objects in the universe were discovered when viewing in the infrared. These bright objects were hidden behind thick clouds of dust that block visible light but glow brightly from the heated dust emitting infrared light. It is believed that nearly half of all star forming regions may be escaping detection when using only visible light for their detection. The properties of cosmic gamma ray bursts, extremely powerful explosions in the universe thought to come from exploding stars and colliding stellar remnants, are being understood now due to observations from multiple portions of the electromagnetic spectrum, including X-rays, visible light, and radio waves. What else is out there? What more can we learn? We now have the capabilities to answer these questions.

This change is happening, but how do we take advantage of it? How do we make sure the public also gains the benefits of this "new astronomy?" The answer is to create a "virtual observatory" (VO) — virtual, in that the user obtains and interacts with the data via web-based tools, and an observatory in the traditional astronomical sense, in that it will be a general purpose instrument, as opposed to an instrument designed for one specific purpose or goal.

Laying the Foundation of a National Virtual Observatory

The idea to create a National Virtual Observatory (NVO) was presented in the National Research Council's decadal review, "Astronomy and Astrophysics in the New Millennium," released in 1999 and published in 2001. The decadal review sets the national priority for astrophysics for the following decade. In the review, the NVO was rated the highest priority for small (less than 100 million dollars) projects. From the decadal review:

"The NVO will provide a 'virtual sky' based on the enormous data sets being created now and the even larger ones proposed for the future. It will enable a new mode of research for professional astronomers and will provide to the public an unparalleled opportunity for education and discovery."

In response to the recommendation given in the decadal review, NASA and the National Science Foundation (NSF) established the Science Definition Team (SDT). The SDT created a report in April 2002, entitled "Towards the National Virtual Observatory." The goal of the SDT was to lay out a plan for implementing the NVO with real proposed science projects as the motivation and direction.

Linking the archives

All of the major NASA missions, along with other national and international missions, store their images and spectra in data archives. There is a wealth of information from those images that has not been explored. That data belongs to the scientists who first proposed the experiment, typically, for about a year. After this period, the data become available to anybody, including the general public. Each archive traditionally sorted and accessed data using their own standards. The archives did not communicate with each other. In the era of multiwavelength, time-domain, and survey astronomy, this is a roadblock to doing good science.

The NVO was tasked with overcoming these barriers by creating common standards by which the archives would catalog their data and communicate with users. In so doing, the NVO would be a one-stop destination where a person could easily access data from any or all of the archives instead of searching separately.

In many ways, the NVO was equivalent to today's airline or hotel reservation systems like Travelocity or Expedia. A traveler can use these services to compare prices, schedules, and amenities among airlines or hotels. The user can choose the hotel or airline that suits them the best. The NVO, likewise, was envisioned to be a central place where astronomers, students, educators, or any other interested user could find images or spectra of any type of object, from any archive.

To successfully create this centralized hub of data access and analysis, the SDT envisioned a three-phase process to implement the NVO:

• Phase I: Conceptual design of the NVO, expanded definition of the science that will drive the development of the NVO, implied technical capabilities, management structure and costing issues.
• Phase II: Definition of the NVO operational/management structure, a detailed implementation plan, increased capabilities implemented within existing data centers/archives/surveys/observatories, and increased community input and involvement.
• Phase III: Implementation of the full-fledged NVO structure with international connections, the start of NVO-based science programs, and the start of routine operations.

Even in this earliest phase of a national virtual observatory, plans were being formulated on how to capitalize on the unique capabilities of the NVO to teach science, technology, engineering, and math (STEM) subjects. From "Towards the National Virtual Observatory":

"The NVO effort also provides a unique opportunity to enhance technology literacy in a broad sense. The NVO will inform, excite, and educate the public about space science and astronomy, and serve as a catalyst for scientific and technological literacy in the United States."

Success of the NVO

The NVO was an ambitious project that was clearly defined by the SDT. In the report by the SDT, it was noted that the foundational and infrastructure problems had to be solved before any operational VO could be put into place.

By the end of the NVO funding in 2010, many of these issues had been solved. There was a management, operations, and organizational structure in place, which is critical for a geographically distributed project like the VO, which has member institutions from all over the U.S. and the world.

A new set of VO-standards were implemented into most of the large astronomy data archives for simple retrieval of information. These standards were created and adopted across the world with the help of the newly formed International Virtual Observatory Alliance (IVOA), which presently includes more than 20 nations with individual VO programs. These include the United States, France, Germany, Canada, China, India, Italy, United Kingdom, Japan, Brazil, Australia, and more.

The NVO and international VO programs were not the only groups building and supporting VO infrastructure and tools during the decade. Microsoft Research was one such leading organization. In 2001, Jim Gray, of the Microsoft Research Center, and Alexander Szalay, who was one of the principal investigators of the NVO, wrote up a viewpoint article for Science, entitled "The World-Wide Telescope."

In this article, the justifications for embarking on a national virtual observatory were given, including strong educational motivations. In the article, Gray and Szalay made a point that the VO can help educate the students and the general public in areas such as astronomy, physics, chemistry, computational science, and mathematics.

The efforts of Microsoft Research's VO efforts have led to the development of the WorldWide Telescope (WWT), a beautiful visualization tool that makes use of the VO infrastructure to provide real astronomical images. Microsoft has dedicated the WWT to Jim Gray, who was lost at sea in 2007 during a solo boating trip.

With the groundwork laid out by the NVO and its national and international partners, the time to use the VO is here. Some tools have been developed for the VO and many more are in the pipeline for use by both professional astronomers and the general public. These tools have features that allow the user to acquire data, analyze data, and learn about the universe through beautiful visualizations.

With the NVO era now over, a new organization has been funded in its place, with the explicit goal of creating useful tools for users to take advantage of the groundwork laid by the NVO. To carry on with the NVO's goals, we hereby introduce you to the Virtual Astronomical Observatory.

The Establishment of the Virtual Astronomical Observatory

The Virtual Astronomical Observatory (VAO) is the U.S. NSF- and NASA-funded VO effort that seeks to put efficient astronomical tools in the hands of U.S. astronomers, students, educators, and public outreach leaders. From the Mission Statement in the "VAO Project Execution Plan (2010)":

"The VAO, building on the success of prior infrastructure developments, is now poised to realize the benefits long-promised to the astronomical research community, and more generally, educators and the general public."

The VAO has a current funding and development path for five years. Many tools are being developed by the VAO and its national and international VO collaborators to make accessing and analyzing astronomical data simple and intuitive for professional astronomers and the general public. Some of these tools include:

• Data Discovery Tool — Retrieve astronomical data about a given position or object in the sky.
• Aladin — Find and overlay images from different parts of the electromagnetic spectrum.
• Cross-comparison tool — Find all objects of a given type or at a given location between all archives.
• IRIS — Find, plot, and fit spectral energy distributions (SEDs). SEDs are the brightness profiles of objects at many wavelengths.
• VOPlot — Plot results from VO queries.
• Skyalert — Monitor real-time alerts of transient events. These include variable stars and supernovae.
• Time series tool — Obtain an object from multiple archives/observations to analyze how it varies its light output with time.
• Montage — Make large mosaic images of survey data.
• Microsoft's WorldWide Telescope — Explore the universe and look at astronomical images taken by many of the world's telescopes with this visualization software. WWT has the unique feature of allowing the user to create special tours around objects that can be shown as video to others.
• Google Sky — Explore the universe and look at astronomical images taken by many of the world's telescopes with this visualization software.

Most of these tools can be found by going to the VAO science site, here. WWT can be found here, and Google Sky can be found here. To help develop and refine the tools, the VAO is working with science teams and EPO professionals. Some of the current science teams run the gamut from those that study star formation and evolution to those that study galaxy formation and evolution.

The VAO has firmly established an E/PO program to deliver the capabilities of the VO to students, educators, amateur astronomers, citizen scientists, and the general public. From a 2010 founding document of the VAO, entitled "A Vision for the US Virtual Astronomical Observatory":

"The VAO will be an invaluable resource in any effort to address public science literacy through the use of astronomy; its rapid access to astronomy data, archives, images and literature through a single point of contact will facilitate the creation and maintenance of programs designed to increase public awareness of science."

See the "E/PO" page to learn about the plans for the VAO E/PO program. See the "About Us" section to learn more about the VAO E/PO team.

United States Virtual Observatory Timeline

2000: Decadal Review names the National Virtual Observatory (NVO) as the top small initiatives project.

2001 July - March 2002: Science Definition Team (SDT) formed in response to Decadal Review

2001, April 23: ITR/IM: "Building the Framework for the National Virtual Observatory" submitted. This is a copy of the original proposal to NSF's Information Technology Research (ITR) Program.

2002, April: "Toward the National Virtual Observatory," a report prepared by the National Virtual Observatory Science Definition Team

2002, June: International Virtual Observatory Alliance (IVOA) founded

2002, July 12: White paper published

2004: First NVO Summer School, The Aspen Meadows Resort, Aspen, Colorado

2005, September 6-15: Second NVO Summer School, The Aspen Meadows Resort, Aspen, Colorado

2006, September 6-14: Third NVO Summer School, The Aspen Meadows Resort, Aspen, Colorado

2008, September 3-1: Fourth NVO Summer School, The Lodge at Santa Fe, Santa Fe, New Mexico

2009, April 3: "The Role of the Virtual Observatory in the Next Decade"

2010, October: Founding document: "A Vision for the U.S. Virtual Astronomical Observatory"

2010, May 15: The NSF and NASA announce a cooperative agreement to create a new research facility for astronomy — the Virtual Astronomical Observatory.

2011, November 30: "VO Community Day" in Boston, Mass., showcasing VO tools to the astronomical community.

2011, December 7: "VO Community Day" in Pasadena, Calif., showcasing VO tools to the astronomical community.

2012, January 8: "VO Community Day" and Educator Workshop, Austin, Texas: "Science Tools for Data-Intensive Astronomy," showcasing VO tools to the astronomical community.

2012, March 13: "VO Community Day" in Tucson, Arizona, showcasing VO tools to the astronomical community.

2012, November 14: "VO Community Day" in Ann Arbor, Mich., showcasing VO tools to the astronomical community.

2012, November 29: "VO Community Day" in Baltimore, Maryland, showcasing VO tools to the astronomical community.

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