For many loyal users, Linux' low cost and high reliability make it an operating system that is truly out of this world. At the astronomy department of the University of Iowa, in Iowa City, however, scientists are using Linux to get a look at other worlds.
The astronomers there rely on a Linux-based software package called Observatory Control and Astronomical Analysis System (OCAAS) from Torus Technologies -- also based in Iowa City, Iowa -- to control the telescopes they use to look at the heavens.
The actual observations of the skies are done at the Winer Mobile Observatory in Sonoita, Ariz., which is operated by the OCAAS software and is networked to the University of Iowa, where viewing is scheduled and data is analyzed. The 20-inch telescope at Winer can be controlled directly from Iowa City, says Mark Trueblood, scientific director of the Winer Observatory. The user simply enters what kind of objects he is looking for stars, for example, or planets or asteroids and the system generates a schedule for viewing. Schedule requests are then sent automatically to the telescope in Arizona, using a standard TCP/IP connection over the Internet. At the observatory in Arizona, OCASS, installed on the telescope control computer, automatically checks to see if there's a schedule and then downloads it. Then, when the sun is twelve degrees below the horizon, OCAAS opens the observatory and starts the telescope. A Charge Coupled Device (CCD) digital camera takes pictures all night and sends them back to Iowa City for analysis.
"If it gets too windy or rains, OCAAS automatically closes the roof of the observatory," says Trueblood. "It can be set for either automatic or manual control."
Telescopes and digital cameras controlled by OCAAS enable researchers to get images equivalent to those obtained from the largest telescopes in the world using photographic plates. According to Rich Williams, vice president of marketing and product development at Torus, current CCD cameras are 100 times more sensitive than older cameras that use photographic emulsions. That means that a CCD camera is as powerful as a telescope with 100 times the light-collecting area, and that uses photographic film. OCASS can be used on any size telescope and with an array of old and new observatory cameras.
The OCAAS software controls CCD image calibration and analysis, a graphical planning and mapping program, and research tools for photometry, variable star searching and monitoring, as well as planning and logging programs. It also includes tools for off-line image display and automated scientific analysis of variable stars, asteroids, supernovae and other celestial phenomena that vary with time.
100 Times More Powerful
Telescopes and digital cameras controlled by OCAAS enable researchers to get images equivalent to those obtained from the largest telescopes in the world using photographic plates. According to Rich Williams, vice president of marketing and product development at Torus, current CCD cameras are 100 times more sensitive than older cameras that use photographic emulsions. That means that a CCD camera is as powerful as a telescope with 100 times the light-collecting area, and that uses photographic film. OCASS can be used on any size telescope and with an array of old and new observatory cameras. The OCAAS software controls CCD image calibration and analysis, a graphical planning and mapping program, and research tools for photometry, variable star searching and monitoring, as well as planning and logging programs. It also includes tools for off-line image display and automated scientific analysis of variable stars, asteroids, supernovae and other celestial phenomena that vary with time.
The astronomers at the University of Iowa are not the only ones using OCAAS. The program is also in use at places like NASA, Lawrence Livermore National Laboratories, McDonnell Douglas, as well as at observatories in Japan, Taiwan, India and elsewhere. "It is the only complete observatory system that is so powerful and easy to use," says Trueblood.
It is also the only commercially available Linux-based telescope control system. The observatory community, according to Trueblood, is used to control systems that are mainly Unix-based. "A lot of the people using the system are from universities, so they're already comfortable with UNIX," he says. "Linux is cheap, it runs on PCs, and it isn't a hassle to use."
OCAAS was originally developed by Elwood Downey, based on the University of Iowa's Automated Telescope Facility and Iowa Robotic Observatory control systems. The software consists of 200,000 lines of ANSI C and the GUI uses X/Windows and Motif 1.2.
Torus, which purchased OCAAS from Downey's company, Clear Sky Institute, Inc., in November 1999, plans to continue improving the software package. "It's currently set up as a single point-to-point interface, but we're working on a true client/server version, where multiple observatories will be able to interact over a network," says Williams.
Torus is considering creating a version of OCAAS for Microsoft Windows NT platforms. But the company is in no rush. "Linux has all of the features you would expect of a modern, fully fledged UNIX operating system," Williams says. "It is our primary development platform and we intend to keep it that way. There is a lot of passion about operating systems in the astronomy community and the world in general. Many of our customers love the fact that OCAAS runs on Linux and it is a major selling point for them."
With the growing enthusiasm and momentum behind Linux, Williams has seen no hesitation among users interested in using OCAAS in its current form. The software brings unprecedented automation to the age-old pursuit of the extraterrestrial, earning its "out of this world" praise in observatories around the globe every day.
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