The American Astronomical Society (AAS) has awarded its prestigious George Van Biesbroeck Prize to Dr. Eric Greisen of the National Radio Astronomy Observatory (NRAO) in Socorro, New Mexico. The society cited Greisen’s quarter-century as “principal architect and tireless custodian” of the Astronomical Image Processing System (AIPS), a massive software package used by astronomers around the world, as “an invaluable service to astronomy.”

The Van Biesbroeck Prize “honors a living individual for long-term extraordinary or unselfish service to astronomy, often beyond the requirements of his or her paid position.” The AAS, with about 7,000 members, is the major organization of professional astronomers in North America.

” The Very Large Array (VLA) is the most productive ground-based telescope in the history of astronomy, and most of the more than 10,000 observing projects on the VLA have depended upon the AIPS software to produce their scientific results,” said Dr. James Ulvestad, NRAO’s Director of New Mexico Operations. “This same software package also has been the principal tool for scientists using the Very Long Baseline Array and numerous other radio telescopes around the world,” Ulvestad added.

Greisen, who received a Ph.D in astronomy from the California Institute of Technology, joined the NRAO in 1972. He moved from the observatory’s headquarters in Charlottesville, Virginia, to its Array Operations Center in Socorro in 2000.

Greisen, who learned of the award in a telephone call from the AAS President, Dr. Robert Kirschner of Harvard University, said, “I’m pleased for the recognition of AIPS and also for the recognition of the contributions of radio astronomy to astronomy as a whole.” He added that “it wasn’t just me who did AIPS. There were many others.”

The AIPS software package grew out of the need for an efficient tool for producing images with the VLA, which was being built in the late 1970s. Work on the package began in 1978 in Charlottesville. Now including nearly a million lines of program code and almost a half-million lines of documentation, AIPS is used at more than 500 sites around the world. The package is a mainstay and a daily tool for most of the world’s radio astronomers, and also has been used by scientists in such other fields as fluid-dynamics simulation and medical imaging.

Over the years, Greisen and his colleagues at NRAO have revised the AIPS package numerous times and expanded its capabilities as new astronomical and computing hardware was developed. The software has been kept independent of specific computing hardware and operating systems, and so has been successfully used on a wide variety of computing equipment.

“We are extremely proud of Eric’s work and congratulate him on receiving this award,” said NRAO Director Dr. Fred K.Y. Lo. “He has shown extraordinary dedication to making AIPS a valuable and effective tool for the world astronomical community, and this award is well-deserved recognition.”

The AAS citation reads, “The 2005 Van Biesbroeck Prize is awarded to Dr. Eric Greisen of NRAO for the initiation, development, and maintenance for twenty-five years of the Astronomical Image Processing System (AIPS). Virtually every VLA and VLBA program relies on AIPS for calibration and image reconstruction, and it has been exported to more than 500 sites worldwide. Greisen, as its principal architect and tireless custodian, has provided an invaluable service to astronomy. Moreover, AIPS represented a new paradigm for the processing of massive astronomical datasets, i.e., a comprehensive software package that was rigorously independent of particular operating systems, which supported portability and adaptability to evolving hardware designs. Beyond the call of duty, Greisen has generously responded to individual queries about the code from users at all levels, sometimes in real time at odd hours to support observations in progress.”

Greisen is the second NRAO scientist to receive the Van Biesbroeck Prize. Dr. Barry Clark, one of the early architects of the VLA who has scheduled that telescope’s observations for nearly three decades, received the award in 1991.

The National Radio Astronomy Observatory is a facility of the National Science Foundation, operated under cooperative agreement by Associated Universities, Inc.