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Unique telescope at Apache Point Observatory aims for new frontiers

New Mexico State University astronomers and collaborators from around the world are embarking on new research missions with a unique telescope at Apache Point Observatory, high in the Sacramento Mountains near Cloudcroft.

The Sloan Digital Sky Survey telescope at Apache Point Observatory has been funded for three years of new research initiatives.

The Sloan Digital Sky Survey, described as the most ambitious astronomical survey project ever, already has charted and measured hundreds of millions of galaxies, stars and quasars during the past five years.

The Sloan Digital Sky Survey II (SDSS-II) will spend the next three years completing the original survey and exploring new areas. It will examine our own Milky Way galaxy as never before and it will sweep the sky for supernovae - exploding stars that can help answer questions about the expansion of the universe.

Kurt Anderson, NMSU astronomy professor and site director of Apache Point Observatory, described the Milky Way project as "galactic paleontology."

"By mapping our own galaxy, we can address questions as to the history of the galaxy - how it accumulated matter, how the stars formed," Anderson said. "It's like exploring the Earth but on a much bigger scale. We want to know what's where and why."

That part of the project is known as the Sloan Extension for Galactic Understanding and Exploration, or SEGUE. The Milky Way observations will be done during the summer and winter months, said Bruce Gillespie, Apache Point Observatory site operations manager.

In fall, the astronomers' attention will turn to supernovae, which may help them unravel the mysteries of the so-called dark energy that is believed to be causing the expansion of the universe to speed up.

"Supernovae are massive stars that explode at the end of their lifetimes," said Jon Holtzman, associate professor of astronomy and one of the researchers involved in the supernova survey. "We have found that a certain kind of supernova, known as Type Ia, all seem to have the same intrinsic brightness when they explode."

Knowing this, scientists can more precisely measure the distances to these supernovae, using them to map the rate of expansion of the universe, and this will help to decipher the nature of dark energy.

"We think we can get a couple hundred supernovae a year," Holtzman said. He and his students will use the two other telescopes at Apache Point Observatory - NMSU's 1-meter telescope and the 3.5-meter telescope owned by the Astrophysical Research Consortium - to do follow-up observations, taking spectra of the supernovae found by the Sloan telescope to determine if they are the Type Ia supernovae needed for the distance measurements.

The NMSU Astronomy Department operates Apache Point Observatory for the Astrophysical Research Consortium, of which NMSU is a member.

During the spring, the SDSS telescope will be used to finish the last bit of the original baseline survey, Gillespie said. "There is kind of a belt in the middle of the survey that's missing, and that belt is only observable in the spring," he said.

Astronomers will take spectra of the galaxies in this belt to complete the original survey, said Rene Walterbos, head of the NMSU Astronomy Department and one of the researchers in the project. Nicole Vogt, another NMSU astronomer, is interested in data from this missing band for her research on galaxy clusters.

Funding for the $15 million SDSS-II project is provided by the Alfred P. Sloan Foundation, the National Science Foundation and an international consortium of research institutions and universities, including NMSU. More than 300 scientists and engineers at 23 institutions around the world are involved in the SDSS-II collaboration.

At times during its early years, the future of the SDSS telescope was uncertain beyond its initial five-year survey, but to Gillespie there was never much doubt that it would find new missions.

"This is such a unique facility, in the context of all the other observatories in the world, it was inevitable to me that we would continue doing something with the Sloan telescope after the original survey was done," he said. "This telescope is the 800-pound gorilla, if you will. For imaging the sky and spectroscopy of large numbers of objects, nobody can touch it."