After scanning the entire sky and capturing breathtaking and scientifically important images of galaxies, stars and other celestial objects, a pair of infrared telescopes has finished its survey work.

For the past three and a half years, the twin telescopes of the Two Micron All-Sky Survey (2MASS), located in Arizona and Chile, have conducted the first high-resolution digital survey of the complete sky. The successful completion of observations marks a milestone in modern astronomy. For the next two years, data processing will continue for the 24 terabytes of archive data, which is enough to fill more than 2,000 hard drives on an average home computer.

"These telescopes have given us the first detailed global view of our Milky Way galaxy and the galaxies that lie beyond," said Dr. Michael Skrutskie, of the University of Massachusetts, Amherst, 2MASS principal investigator. "The resulting databases and source catalogues are a treasure trove which will be mined for discovery by scientists and the public alike for decades to come." The University of Massachusetts was responsible for the development and construction of the 2MASS telescopes and cameras and managed the collection of survey data.

"The 2MASS telescopes and cameras operated with incredible efficiency and were workhorses for more than a thousand nights," said Dr. Roc Cutri, project scientist at the Infrared Processing and Analysis Center (IPAC) at the California Institute of Technology and NASA's Jet Propulsion Laboratory in Pasadena, Calif. "The facilities collected data 99.5 percent of the available time during the mission, and only a few nights were lost due to hardware failures. That's a remarkable record for any astronomical observatory on the ground or in space."

IPAC developed the software system to convert raw digital data from the telescopes into stunning images and catalogues useful to astronomers. IPAC also archives and distributes those data to the public via the Internet, in essence, turning home computers into desktop observatories.

The 2MASS survey is the most thorough census ever made of our Milky Way galaxy and the nearby universe. It detects infrared wavelengths that are longer than the red light in the rainbow of visible colors. Infrared light penetrates dust more effectively than visible light, so it is particularly useful for detecting objects obscured within the Milky Way, as well as the faint heat of very cool objects that give off very little visible light of their own.

To cover the entire sky, 2MASS used two highly automated, 1.3-meter (51-inch) diameter telescopes, one at Fred Lawrence Whipple Observatory on Mount Hopkins, Ariz., the other at the Cerro Tololo Inter-American Observatory in Chile. The Arizona telescope began operations in June of 1997, while the Chilean telescope began scanning the sky in March 1998. Both facilities completed their work on Feb. 15.

Catalogues containing more than 300 million stars and galaxies extracted from the images have begun to yield significant astronomical discoveries, and will provide an invaluable reference frame to steer NASA's Space Infrared Telescope Facility (SIRTF), scheduled for a 2002 launch, and other future infrared space missions.

The survey has:

Uncovered numerous stars with such unique characteristics that astronomers have had to update a century-old classification system of known types of stars, and also unveiled the coolest brown dwarfs, or failed stars, known to date;

Detected previously unknown galaxies seen behind the disk of our own Milky Way;

Mapped new star-birth regions both in our Milky Way and in other galaxies; and

Discovered many new, dust-obscured active galaxies and quasars in the distant reaches of the universe that were missed by earlier surveys that used visible and ultraviolet light.

The 2MASS project is a collaborative effort between the University of Massachusetts and IPAC. Part of NASA's Origins Program, 2MASS is primarily funded by NASA's Office of Space Science. Additional funding was provided by the National Science Foundation. In addition to enabling groundbreaking new scientific discoveries, 2MASS results will also benefit future Origins missions, including SIRTF and the Next Generation Space Telescope, and will also help scientists plan observations for the Hubble Space Telescope and the Stratospheric Observatory for Infrared Astronomy.

A sampling of 2MASS images is posted at . Additional information about 2MASS is available at .

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