Citing "teamwork and dedication in the development of the world's largest star catalog to be used in pointing the Hubble Space Telescope (HST)", NASA has given its Public Service Group Achievement Award to The Guide Star Catalog Group at Space Telescope Science Institute (STScI). Dr. Barry Lasker, Chief of the Catalogs and Surveys Branch, accepted this award on behalf of the group in a ceremony at Goddard Space Flight Center on March 30.
NASA annually recognizes non-government employees who have made outstanding accomplishments which have contributed substantially to the NASA mission.
HST utilizes Fine Guidance Sensors to locate and lock onto a pair of guide stars near the edge of the telescope's field of view. The GSC was constructed to ensure that guide stars are available wherever the HST looks. The catalog serves as a database which supports the automated scheduling of observations and telescope operation without direct or "realtime" control from the ground.
A digital map of the entire sky, the GSC is 60 times larger than any existing catalog and contains almost 19 million celestial objects, including 15 million stars between 9th and 15th magnitude. The catalog was constructed by scanning and converting into digital form a total of 1,477 sky survey plates taken with the Oschin Schmidt Telescope on Palomar Mountain (operated by the California Institute of Technology) and the UK Schmidt Telescope in Siding Spring Australia (operated by the Anglo-Australian Observatory).
In constructing the catalog, the GSC Group faced unique challenges in large database construction, maintenance and access software. The project, by necessity, required a tremendous amount of experimentation, innovation, and reliance upon emerging computer data storage technologies.
Following four years of prototyping, design and development, the catalog construction process began in 1985 and required another four years to complete. Ultimately, GSC programmers wrote some 200,000 lines of computer code to help construct the catalog. Plate scanning and data processing alone required two 8-hour shifts, seven days per week and grew to three shifts for about one year.
The GSC Group utilized optical disk technology to solve the archival and distribution problems associated with this enormous sky inventory. The raw Schmidt-plate scans fill 400 optical disks, with each disk containing nearly 1.6 billion bytes of data apiece. For distribution to astronomical institutions, the entire GSC was placed onto a set of two CD-ROM disks. Each disk stores nearly 600 million characters or the equivalent of a printout on 8 1/2-by-11-inch paper measuring 30 miles long and weighing one ton.
To easily access the raw plate scans, the GSC Group developed a user-friendly software package called the Guide Star Astrometric Support Package (GASP). Mainly used for planning observations, GASP quickly provides HST users with precise information about their target fields and can display many types of digital images made with almost any telescope.
In addition to its support of HST operations, the GSC serves as a major reference for ground-based astronomy applications, such as tracking comets and asteroids, providing precise finder charts, and obtaining large numbers of stellar spectra using fiber-optics.
Lasker, a 12-year veteran on the HST project, served at Cerro Tololo lnter- American Observatory from 1969-1981. He holds a Ph.D. in Astrophysics from Princeton University.
The members of HST Guide Star Catalog Group are: David Allen, John Baum, John Baumert, Gerald Blackwell, Joseph Buckley, Marc Damashek, Robert Denman, Napolia Dunn, Aaron Dutton, Anatoly Evzerov, Yuri Frankel, Bruce Gillespie, Joseph Harrison, Christopher Harvel, Adolph Hendrickson, Helmut Jenkner, Deborah Kenny, Dennis Kilroy, James Kinsey, Victoria Laidler, Robin Lerner, Ray Lucas, Steven McLaughlin, Brian McLean, Ed Medeiros, Beverly Owens, James Phillips, Joseph Pollizzi, Daniel Rehner, Paul Rigterink, Donald Rosenthal, Jane Russell, Michael Shara, Elizabeth Siciliano, Bernie Simon, Caroline Simpson, Conrad Sturch, Denise Tullos, Allen Wentink, Daniel Wilson, Barry Wishner, William Workman, and Gerald Zavage.