The Lone Star Observatory
It may be Oklahoma, but this amateur-built observatory is all Texas.
- By Eric Adams
- Air & Space magazine, July 2002
It’s a hot afternoon in north Texas. oppressive humidity. Bright sunshine. Lots of bugs. After droning on for miles down a series of wide, lonely highways, we stop off for lunch at a local truck stop, our eyeglasses instantly fogging up as we climb out of our S.U.V. and drop down onto the dry dirt parking lot.
Inside, we grab a table and continue talking about the sublime pleasures of looking at the night sky through a handmade, 24-inch-diameter telescope. We’re likely the only ones in this particular restaurant talking about stars, galaxies, nebulas, and globular clusters. In fact, we’re drawing glances. But Barry Smith, pipe always in hand, is an irrepressible sort, and the idea of showing off his pride and joy—the telescope he and 11 other big-thinking Texans spent over a decade designing, building, and perfecting—keeps him rolling exuberantly along amid the stern-faced truckers chowing down chicken-fried steak. Besides, Smith is the kind of guy who in 30 seconds could persuade these fellows to join us later for an evening under the stars.
Right now he’s focused on getting his guests pumped up about tonight’s viewing. He brags about the telescope’s f/16 focal ratio, which determines the scale and quality of its images. (A focal ratio is a function of the mirror’s shape and the length of the path the light travels after entering the instrument. A ratio of f/16 means that path is 16 times the mirror’s diameter.) “There’s magic at f/16,” says Smith, jabbing his pipe stem toward us. “That’s what our mirror designer said when we were designing the scope, and he was right. The images through this thing are so bright and so large. M57? Oh my God—it fills the field of view!”
Smith, who sells business jets for a living, is the de facto leader of a group of well-heeled amateur astronomers—doctors, engineers, and computer scientists among them—who decided a little more than a decade ago to pool their resources and build themselves an observatory. After years of site-scouting, countless weekend trips from the Dallas-Fort Worth area for construction efforts, many hours in the metal shop, and an investment of over $125,000, the group created the Lone Star Observatory, one of the finest ever built by amateurs—and among the first of the amateur observatories to be completely computer-controlled.
We leave the truck stop and continue our journey, eventually crossing the state line into southern Oklahoma and entering the final leg, five miles of bumpy dirt road. Finally, we pull up to a 200- by 200-foot compound surrounded by a 10-foot-high chain-link fence topped with barbed wire. Inside are two buildings, one a small windowless rectangle and the other round and capped with a bright white dome.
Smith started seeking partners for the venture in the late 1980s among the customers of a small astronomy equipment shop he owned. “At the time I didn’t really have the money,” says Jack Hudler, a computer scientist, “but the project was so terribly interesting. He wanted to build an observatory, with a whole dome, in its own building—I love that kind of project. Then he pushed my button when he said he wanted to computerize it. That really hadn’t been done before by amateurs.”
The group began meeting to plan the project, and one thing quickly led to another. “We started out wanting to build a Volkswagen, and we ended up with a Mercedes,” Smith says. “Each of us put in $3,000, and as we got farther and farther into the planning, we realized there were more and more things that we wanted. We would vote on something, it would pass, and we’d all put in more money.” They agreed early on, for example, that they all wanted a separate clubhouse, with bunks, a kitchen and bath, and a living area in which they could come in to relax and cool off or warm up, since the observatory would have no climate control—telescopes need to be the same temperature as the outside environment, or air currents (warm air mixing with cool) will distort the images. They also wanted the scope to be a premium instrument with a rock-solid mount and a large-diameter mirror. The larger the mirror, the more light a telescope will collect and the brighter, more detailed the images in its eyepiece will be. Then, of course, there would be the computerization, the motorized dome, and a site far away from city lights to ensure dark skies.
While we wait for those dark skies to come, other members—Hudler, Jean Walker, Gary Mueller, and John Louden—straggle in. Some enter the clubhouse to go over star charts, read astronomy magazines, and catch up on one another’s lives; others go to the dome to test the computers and get out all the eyepieces. (The optics in an eyepiece determine the magnification of the object in view. For Mars, which occupies a tiny point in the sky, higher magnification is desirable; for a nebula that spreads out over a large area, astronomers choose an eyepiece with lower magnification in order to see the entire object.) With its small air conditioner working hard—it is clearly going to be needed throughout the night—the clubhouse is a cool, dim environment. Astrophotos and star maps hang on the walls, and the refrigerator in the galley kitchen is stocked with sodas and snacks.
Walker, a former political science professor who now describes herself as a “full-time volunteer,” says she joined the group to have access to a large and sophisticated telescope. “Seeing the Whirlpool Galaxy for the first time in the telescope took my breath away,” she says, clasping her hands together. “And I haven’t lost any of that first experience. It’s there every time.”
Smith adds that trips to the observatory can soothe frayed nerves. “On a bad day, you can drive up here and stay for just two hours,” he says. “There’s something about getting out here for a little while—what you’re worrying about just ain’t very damn important. You can calm down and just relax.”
Though amateurs have contributed important discoveries to the field of astronomy, most have no scientific agenda. Rather, they take pleasure in the learning process—studying galaxies, nebulas (gaseous remnants of exploded stars), and star clusters as they read about the objects. And of course they also enjoy what can be spectacularly beautiful sights. “Galaxies sometimes look like little puffs of cotton,” Walker says. “Then you realize what you’re looking at. Those are the things that give me chills.”
Many members, though, do have well-developed observing programs, in which they study, for example, the intricacies of double stars (two stars that orbit each other), variable stars (which change brightness), or distant galaxies. The group’s telescope is easy to use and has precision optics that show most major categories of celestial phenomena in great detail, so users can modify their programs as quickly as their interests change.
Bringing all this about took roughly three years, beginning with the site selection. The members found a dark site adjacent to one used by the Texas Astronomy Club, and they purchased the one-acre plot for $1,000. Construction began in 1988, with each member contributing some form of sweat equity. While some focused on the clubhouse, the rest worked on the concrete base on which the telescope would sit or the design and construction of the dome. “We had 12 well-educated professionals who’ve never built anything in their lives,” Smith says. “The early part became a wonderful learning experience for all of us. I mean, just how do you build a round building with a rotating roof?”
They studied other observatories to get ideas and broke off into teams to research the computer controls, the mount, and the telescope itself. They finally decided on the design that was the easiest to maneuver, provided the most accessible eyepiece position, and gave them the best views: a classical Cassegrain, which uses a large primary mirror and a smaller secondary one that reflects the light back down through a hole in the center of the primary and into an eyepiece.
As the members laid foundations and framed the two buildings, Mueller, an engineer with an oil well pump manufacturer and one of the few knowledgeable about construction, worked out the design for the steel equatorial mount, which has two arms that hold the telescope between them and a base that is polar aligned—oriented parallel to Earth’s rotation axis and angled to match the observatory’s latitude, enabling it to more easily track objects as Earth’s rotation causes them to appear to move across the sky. Then he built it. “We had a lot of extra room in the machine shop at work and some equipment that wasn’t being used,” Mueller recalls, “so I worked from five until 10 every night for a year to do it.”
Meanwhile, Smith and some other members had found a renowned optical engineer, Jerry Brunache, who convinced them that a certain mirror design—24 inches in diameter and shaped to a focal ratio of f/16—would give them magnificent, large-scale images with few optical defects. As Brunache manufactured the mirror, Hudler worked on the computerization, which he had to invent as he went along. He obtained publicly available databases of sky objects to get coordinates for the computer’s aiming software. It works by first determining where the telescope is pointed from the positions of its gears; then, using the coordinates of the object to be studied, it calculates where the telescope needs to go. Hudler worked to get the software to accommodate a variety of variables, from built-in errors within the electrical motors to the flexing of the 17-foot-long telescope as it moves up and down. When the telescope began operation in 1990, he began testing the software by repeatedly selecting a particular star, slewing away from it, then checking to see if the computer could find the object again.
A number of refinements were necessary. “At first I didn’t have a clue about how to correct these things,” says Hudler, sitting cross-legged on the observatory floor and cleaning a telescope that is much smaller—though still one many backyard observers would cherish as their primary instrument—and that serves as a “finder” scope. “But trial and error and a lot of thinking helped me sort it out. When we fixed them, the computer started nailing every object.”
When darkness falls, the user goes to the telescope’s control center, a desktop computer, and selects what he or she wants to observe (using either common names—Ring Nebula, M31, etc.—or numbered catalog designations). The computer sends the telescope slewing to the proper position. A recent upgrade provides precise simulations on the computer screen of the eyepiece view, point-and-click aiming, and detailed information—size, magnitude, distance, composition—about all objects. Then the observer sits on a large, wheeled, stair-step chair to line up with the eyepiece and uses a hand controller to rotate the 20-foot-diameter, 21-foot-high dome so its narrow opening is lined up with the telescope. The controller also adjusts the focus and moves the telescope around without any computer assistance—usually for random cruising around the universe.
At the eyepiece, the images are indeed spectacular: wispy details in cloud-like nebulas, dark lanes in distant galaxies, and stars so faint that they are inaccessible to most telescopes amateurs buy. Globular clusters, in which thousands of densely packed stars appear as tight spheres, show stars resolved straight to the core. We are eager to see what the scope will reveal of Jupiter, Saturn, and Mars, which at this time of the year won’t rise until after 3 a.m.
Each Lone Star member is entitled to sole use of the telescope a certain number of days per year. The rest of the evenings, such as this one, are open to everyone. The members often bring up school classes or scout troops, or individual young people interested in astronomy. This evening the members alternate at the eyepiece, taking time to discuss what they’re seeing and what might be an interesting next target. When not at the eyepiece, they stretch out on recliners on the observatory’s deck to enjoy the sky and chat. “I’ve always marveled that we were able to put this thing together without much disagreement,” Hudler notes. “Nerves got frayed a couple of times, but decorum was kept at a professional level.”
Inside the clubhouse, the lights, instead of the customary white, are a dim red, which helps preserve essential night vision. Even the refrigerator is equipped with a red light, to eerie effect—when you open the door, the light renders the Coke cans virtually invisible.
At about 2:30 a.m., we turn in for a two-hour nap, then get up to observe Jupiter and Saturn, which by then have risen in the east. Unfortunately, the early morning has also brought in a thick haze, and the sky is virtually impenetrable. Jupiter and Saturn are both disappointing—revealing about as much detail as you would get with an average backyard telescope under ideal conditions. “This is part of the risk,” Walker says. “The weather can completely turn on you.”
But all is not lost. As we gather outside, a bright meteor streaks across the sky, breaking into chunks that leave long, dramatic trails.
Later, as we all leave for breakfast, the members invite the visitors to return. You can’t see the universe in only one night.
Aiming for the Stars
The telescope’s base is angled, so the shaft from the right ascension gear can be kept parallel to Earth’s axis. That alignment helps the telescope to track various objects as they “move” across the sky.
Calibrated into millions of steps, the computerized gears can move the telescope in tiny (arc second) intervals. The computer plots each coordinate and then actuates the motorized worm gears (inset) to move the telescope.