Early Robotic Telescope
David Todd (1855-1939), an astronomer at Amherst College, developed a cluster of automated cameras and small telescopes which he placed on an English equatorial mount. A container of sand was topped with a heavy weight and pierced at the bottom so that a uniform flow of sand allowed a counterweight to drop and power the slow movement of the assembly. Camera shutters were fired, and plate holders were shifted in a precise sequence controlled by a pneumatic system using parts from a pedal organ. Todd's first attempt at automation, on December 22, 1889, took place during a solar eclipse expedition to West Africa. Although everything worked, he was clouded out. David persisted and on his third expedition (to Tripoli) he made the first successful observations with a robotic telescope on May 28, 1900 [1, 2].
Around 1965 a small computer-controlled telescope was put into operation at the University of Wisconsin’s Pine Bluff Observatory to provide real-time measurements of extinction coefficients. This 8-inch, f/4, off-axis, UBV photometric telescope was a spinoff from the space telescope program being actively pursued in Wisconsin [3, 4]. The system was controlled by the very first production (Serial #1) DEC PDP-8 minicomputer which featured a magnetic-core memory of 4096 12-bit words contained within a 4-inch-on-a-side cube. The system was reliable enough to operate 3 or 4 nights in a row without the need for human input. Although it didn’t operate very long, the Wisconsin-8 should, I feel, be credited for being the first robotic telescope in the modern sense of the word.
About the same time, several remotely located telescopes were controlled by linking them to a distant main-frame computer. A 50-inch Boller & Chivens telescope installed at Kitt Peak National Observatory was controlled remotely from a main-frame computer in Tucson some 40 miles away . Although automation was achieved, the system was not reliable enough for continued operation and the telescope was modified to support manual observations. Sterling Colgate also linked a remote robotic telescope to a main-frame computer in Socorro, New Mexico and similarly found that reliable operation could not be achieved. What was really required for reliable, affordable mountaintop observatory automation, however, was microcomputer control. Enter the Fairborn Observatory.
The first successful robotic telescope observations were made with a pneumatically controlled array of telescopes and cameras on May 28, 1900 in West Africa (left). In 1965, Art Code and his associates at the University of Wisconsin achieved successful computer-controlled robotic operation with a PDP-8 minicomputer with 4 K of RAM (right).
Fairborn Observatory Origins
In late 1978, I was a research supervisor at Wright-Patterson Air Force Base near Dayton Ohio. While attending graduate school at the Air Force Institute of Technology, I looked into what basic scientific research I could conduct on my own with modest personal funding. I quickly narrowed my search to astronomy and spent lunch hours for a week at the Institute’s library looking through the previous five years of the Astronomical Journal. I glanced at each article, asking: could I have conducted similar research and written a similar paper? Although I did not have the background for purely theoretical investigations, I realized my background in electrical engineering would be helpful for instrumented observations. While many of the papers reported observations made with large telescopes—not practical for my small backyard on a limited budget—there were 28 papers reporting photoelectric observations of variable stars made with telescopes with apertures of 16 inches or less.
Drawing the obvious conclusion, I ordered a 10-inch Cassegrain mirror set from Coulter Optics, 10 and 12-inch worm gears from Thomas Mathis (I was his first customer), a 1P21 RCA photomultiplier, and a strip chart recorder. A TRS-80 microcomputer was purchased for data reduction . In early 1979 while waiting for the ground to thaw so I could dig the foundation for the telescope’s pier, I built the telescope and photometer and familiarized myself with the TRS-80 and BASIC programming. My observatory was named after the nearby town of Fairborn, Ohio.
Initial photometric observations were of eclipsing binary stars suspected of having large dark spots on one of the stars. As the star spots moved about or got larger or smaller, the shape of the photometric eclipse light curve reflected these changes. This cooperative program between about a dozen small observatories was coordinated by Douglas Hall, an astronomer at Vanderbilt University.
In order to meet Doug Hall and other photometrists in person, I organized a small workshop which was held at the Dayton (Ohio) Museum of Natural History in June 1980. Attendees Douglas Hall, Arne Henden, Ronald Kaithuck, Ken Kissell, Jerry Persha, and I all went on to play an active role in the development of early robotic telescopes after this initial meeting. Doug stayed on after the meeting and we launched the International Amateur-Professional Photoelectric Photometry (IAPPP) organization . We edited the first issues of its quarterly publication, the IAPPP Communications, which continued for over two decades with over 1000 subscribers from 40 countries. I suggested meetings also be held on the west coast, and IAPPP West began its annual conferences in 1981 and has held them every year since then. IAPPP West was eventually renamed the Society for Astronomical Sciences.
Making photometric observations was time consuming, tedious, and boring. Stars had to be found and centered, filters changed, and the strip chart recorder turned on and off—the same thing over and over, hour after hour. On cloudy nights, the strip chart results had to be painstakingly measured with a ruler and the numbers typed into the TRS-80 for final reduction which, gratefully, was totally automated. To make the process less tedious and more efficient, I developed an interface between the photometer and TRS-80 that not only logged the data directly but also changed the filters via a stepper motor. As the computer had to be told what was being logged, I wrote a BASIC program that led me, the observer, through a sequence of variable, comparison, and check star and sky observations in U, B, and V filters. The instructions, generated by the TRS-80 in my study, were displayed on a remote monitor out in the observatory and I responded by following the instructions and making choices on a remote keypad . As each 10-second integration proceeded, the changing signal was plotted on the remote monitor—a “paperless strip chart recorder” of sorts.
The computer was now in charge, doing everything except finding and centering the stars—which it delegated to me. Now I was totally bored! My wife was complaining about my late hours, while at the laboratory where I was a branch chief, the director wondered why I was falling asleep in staff meetings. Obviously, the computer needed to take over finding and centering stars so I could get a good night’s sleep, thus restoring marital bliss and the good will of my boss!
Russ Jr. (1979) centers a star at the Fairborn Observatory’s first telescope (left). The UBV photometer, DC amplifier, high voltage power supply, and strip chart recorder are visible. A Radio Shack TRS-80 microcomputer (right) was used for data reduction. Also shown are a thermal printer, modem, and (upper left) a floppy drive (right).
The first of a series of annual conferences Russ organized (upper left) was held in June 1980 at the Dayton Museum of Natural History. By 1984, the annual conference had grown to a substantial size as can be seen by the many attendees (lower right) posing in front of the Fairborn Observatory. Microcomputers in Astronomy  and Microcomputers in Astronomy II  were book-proceedings from these early conferences.
Doug Hall and Russ Genet wrote a photometry guide in 1981  that was issued as a second, hardback edition  in 1988 (left). Data logging and control circuits and attendant programs for the TRS-80 were published in 1982 in what appears to be the first-ever book on real time control with microcomputers . This book led to many other control applications of the TRS-80 including those at the rat and pigeon laboratory of B.F. Skinner, the famous behavioral psychologist at Harvard.
Automation at the Fairborn Observatory
In 1981—while visiting a sister Air Force laboratory division in Mesa, Arizona—an amateur astronomer, Jeff Hopkins, kindly introduced me to a number of Phoenix-area photometrists, including Louis Boyd. Lou had been helping Richard and Helen Lines with photoelectric equipment at the Lines’ observatory in Mayer, Arizona. Richard operated the telescope, while Helen recorded the observations. Lou kept suggesting how various portions of the process could be automated. Content with their smooth two-person manual operation, Helen told Lou that they were not interested in automation. If Lou wanted an automated system, he should go build his own, which Lou set out to do. Having a common goal of full automation, Lou and I joined forces under the rubric of the Fairborn Observatory (east and west).
What we developed was simple low-cost automatic photoelectric telescopes (APTs) that did not even have (expensive for us) position encoders. Each axis was driven by a stepper motor under computer control. The photometer not only measured the brightness of stars but, via the Hunt and Lock routines we devised, was able to find and center stars. A symmetrical sequence that involved 10 slews and some 33 individual 10-second observations was made of the variable, comparison, and check stars and a sky background in a “group” to obtain differential photometric magnitudes in three colors. The entire sequence, which involved hundreds of small telescope movements, took about 11 minutes to complete. During a typical winter night, about 50 groups could be observed, involving the finding and centering of over 400 stars. The two initial Fairborn Observatory robotic telescopes—the Phoenix 10 (Loy’s) and Fairborn 10 (mine)—continued to operate for over two decades, each finding and centering about 3 million stars and making over 8 million 10-second integrations.
Initial automatic operation was achieved at the Fairborn Observatory (west) in October 1983 with Lou’s Phoenix 10 telescope located in his backyard in Phoenix, Arizona. I achieved automatic operation at Fairborn Observatory (east) some six months later with the Fairborn 10 [14, 15, 16].
In 1983, Perry Remaklus at Willmann-Bell asked me to write a book on the microcomputer control of telescopes. I was not very far into this book when a large package arrived in the mail—a fan-folded printout of a master’s thesis on Telescope Control written by Mark Trueblood at the University of Maryland. Mark wondered if it would serve as the basis for a book. I assured him that it would and invited him to be the first author of the book I had initiated. Our book, Microcomputer Control of Telescopes, published in 1985, was widely read . Mark and I wrote a second version a dozen years later .
Ohio, unlike Arizona, was not a good location for automated photometry. Not only was it often cloudy, but the weather often changed, rather unpredictably, during the night. I began sleeping out on a cot with the telescope on clear nights, hoping that if it clouded up and started raining, I would wake up in time to close the roll-off roof before the telescope was completely drenched. While I could have installed weather sensors and roof control and fully automated the observatory, a better solution soon presented itself.
The Hunt and Lock routines used the photometer itself to find and center the stars. A symmetrical sequence of some 33 individual 10-second observations were made of variable, comparison, and check stars and sky background (termed a “group”) through Johnson U, B, and V filters.
Russ, Lou, and the Phoenix 10 robotic telescope (left) pose before its first full night of automatic operation on October 13, 1983. Russ assembled the Fairborn 10 robotic telescope (right) from a DFM Engineering mount, Meade 10-inch Schmidt Cassegrain optics, and an Optec SSP-4 VRI photometer.
Mark Trueblood and Russell Genet’s two books (1985 and 1997) on the microcomputer control of telescopes were quite influential not only with respect to telescope control, but also the full automation of telescopes. Mark (right) has worked for many years as an instrumentation engineer for the National Optical Astronomical Observatories.
The Automatic Photoelectric Telescope Service
In 1985, I attended the winter meeting of the American Astronomical Society held that year in Tucson, Arizona. One afternoon during the meeting, Sallie Baliunas—an astronomer at the Harvard-Smithsonian Center for Astrophysics—took Lou and I on a tour of the Smithsonian Astrophysical Observatory and the Multiple Mirror Telescope, both on Mt. Hopkins south of Tucson about halfway to the Mexican border. We fatefully drove past an unused roll-off-roof building that Sallie explained to us had been used for satellite tracking with a laser ranger and Backer Nunn camera.
Although it was shirtsleeve weather in Arizona, it was -20° F in Ohio, and my wife mentioned that our water pipes had frozen solid. Recognizing a unique opportunity, I suggested that we move to Arizona. Six months later we bought a house in Mesa, Arizona where I had been assigned to our sister Air Force laboratory as a Branch Chief supervisor. A few months later I visited David Latham, the Director of the Smithsonian Astrophysical Observatory. We agreed that the unused satellite tracking station would make an excellent home for our robotic telescopes. A ten-year agreement was drafted. The Smithsonian Institution would provide the facilities, utilities, and use of 4-wheel drive vehicles to negotiate the steep dirt access road. The Fairborn Observatory would provide and operate the robotic telescopes. My Fairborn 10 telescope, moved to Arizona from Ohio, would be devoted to Sallie Baliunus’ solar-type star research program to provide photometric VRI measurements to compliment her spectroscopic observations being made with the historic 60-inch telescope on Mt. Wilson. When Dave notified us that the Secretary of the Smithsonian Institution had approved the agreement, Lou and I had my Fairborn 10 robotic telescope bolted down to the floor of the observatory in less than 24 hours.
After I gave a talk on our robotic telescopes to the Astronomy Division at the National Science Foundation, they suggested we submit a proposal for a third robotic telescope. We teamed up with Doug Hall to propose a 16-inch telescope that was soon built by DFM Engineering. The Fairborn Observatory provided the control system.
For over a year, Lou and I spent most of our weekends and vacations on Mt. Hopkins. We operated the robotic telescopes while we were there and worked on automating the observatory itself so we would not have to continue making the long, four-hour drive from Phoenix to our observatory. We designed and built the weather sensors ourselves, modified the northern wall of the observatory to tilt down, thus giving our telescopes access to the northern skies, and installed a large bank of batteries in our control room to power the closure of the five-ton roof when commercial power failed (which was not unusual). A microcomputer was dedicated to reading the weather sensors, checking the roof and telescope’s limit switches, controlling the roll-off roof and tilt-down wall, and authorizing the robotic telescopes to observe or commanding them to park. The observatory control computer also kept a log of the commands it issued, weather sensor readings, and the status of each telescope.
On weekends, when we were on the mountain, we enabled the observatory to run itself. Finally, after reasonably reliable autonomous operation for many weeks had been achieved, we drove off one morning without disabling the observatory, leaving it to run without any human supervision or oversight whatsoever. It was a nerve-wracking moment. Should the telescopes fail to park properly, the low roll-off roof would “decapitate” the telescopes. If the roof failed to close, it could rain or snow on the telescopes. For many months we could not resist, now and then, calling the night operators at the other (manual) telescopes on the mountain and asking them to take a peek in our observatory. Were the telescopes still operating okay? One day we got a call from one of the Multiple Mirror Telescope day crew members who informed us that, as he drove by our observatory, he noted that the roof rolled open, then it rolled closed, then it rolled open... While our telescopes normally operated reliably, not really knowing what was happening at our observatory began to drive us nuts!
For 10 years, the Automatic Photoelectric Telescope (APT) Service on Mt. Hopkins was a joint operation between the Fairborn Observatory and the Smithsonian Astrophysical Observatory [19-23]. Located at 8010 feet elevation on the top of a ridge (left) between the Multiple Mirror Telescope and the Fred L. Whipple Observatory, the Fairborn Observatory telescopes were housed in a roll-off roof (center). Sallie Baliunas (right) was the key APT Service participant from the Harvard-Smithsonian Center for Astrophysics.
My Fairborn 10 robotic telescope (left) was the first to be installed at the Automatic Photoelectric Telescope (APT) Service on Mt. Hopkins in 1985. Left to right (back row): Russ, Don Hayes, Doug Hall, and Ken Kissell. Front row Russ Jr. and Judith Kissell. Lou’s Phoenix 10 was the second telescope on Mt. Hopkins, while the Vanderbilt 16 (shown with Doug Hall, right) was funded by the National Science Foundation.
The weather sensors (left) included a rain sensor (left side of pole) and cloud detector (right side of pole). An observatory control computer was added to our wall-mounted lineup of control systems (shown at the right with Lou Boyd).
To reduce our worries, we devised what we called a “Morning Report.” Every morning, after the observatory control computer had parked the telescopes and closed the roof, it initiated a modem call to us and downloaded a summary of the previous night’s operation in terms of weather, observatory control commands, and how successful each telescope had been in making its observations. This greatly reduced our worry factor, although the reports were occasionally inconclusive. For instance, we once received a morning report that the previous night had been clear but that it had been raining—same thing the next report. Puzzled, we called one of the night telescope operators who informed us it had been clear both nights. A drive to the observatory revealed that a bird had used our rain sensor as a toilet facility, thus producing the erroneous rain indications.
By 1987 we had a smooth-running operation. Once a list of program stars (and the attendant comparison and check stars and sky location that formed a group) was loaded on a telescope along with group observational priorities (whether or not they should be observed with respect to the moon being up, etc.), the telescope would itself choose the groups to observe. Various rules such as “first to set in the west” and “nearest the meridian” could be associated with each group. This was not a rigid observational sequence list but rather a quasi “artificial intelligence” approach (although the “intelligence” of the telescopes was limited by the slow speed and small size of our computers).
Infrequently loading the stars “once” and letting the “AI” program manage observations worked well for relatively fixed observing programs such as Sallie Baliunus’ solar-type stars on my Fairborn 10, or Greg Henry and Doug Hall’s spotted eclipsing binary program on the Vanderbilt 16. It did not work so well on Lou Boyd’s Phoenix 10 telescope which had a mix of often short-duration observational requests from multiple observers in our “rent-a-star” program where groups (33 separate observations taking a total of about 11 minutes) were made for $2 per group. It was time-consuming to keep up with the changing requests and interface with the multiple Phoenix 10 users. We did, after all, have an observatory to run, not to mention fulltime jobs and families. This difficulty was resolved by assigning a “Principal Astronomer” (PA) to each telescope. Mike Seeds kindly volunteered to be the PA for the troublesome Phoenix 10 telescope. He handled the interface with all of its many users, resolved observational conflicts, provided us with the consolidated observational program, provided the multiple users with uniform data reduction, kept an eye on the quality of the data, and collected the modest $2 fee for each group successfully observed [24, 25]. This worked well indeed, and every telescope from then on was always assigned to a single PA. Mike was the PA for the Phoenix 10 for over two decades, serving dozens of users, including many students—a major contribution to automated astronomy.
Four times a year we mailed a floppy disk with a quarter’s worth of data to each PA. We were always concerned that some equipment degradation that subtly ruined the data would not be discovered until the PA reduced the data. While this never happened, it did inspire us to devise a procedure and high-level language—the Automatic Telescope Instruction Set (ATIS)—that allowed the PAs to send in observational programs via modem each morning after observatory shut down, and have the previous night’s observations automatically sent to them via modem for immediate reduction if they so desired [26, 27, 28]. Bandwidth requirements for aperture differential photometry were modest (unlike imaging observations), and were readily handled by modem and soon the Internet in its early days.
Although the precision of our automated photometry was good, it was not as good as the best manual photometry such as that produced by Wes Lockwood at Lowell Observatory. Not to be outdone by mere human observers, I organized two workshops on “Precision Automated Photometry.” Under the guidance of Andy Young, a photometry expert at California State University, San Diego, we thoroughly discussed all the possible errors that might affect the precision and accuracy of differential photometric measurements. We then considered how we might minimize these error sources through photometer design, automated observations of standard stars throughout the night, and automated but human-monitored quality control analysis [29, 30]. Lou Boyd designed a precision photometer, and Greg Henry and Lou developed the quality control procedures and analysis program [31, 32]. The result was photometry of the highest precision and accuracy—better than what human observers could produce.
As word of our successful operation spread, additional telescopes were funded by the National Science Foundation and others. We designed a compact 0.8-meter (32-inch) telescope specifically for automated photometry. We were able, after the Backer-Nunn camera had been removed, to “shoehorn” four of these telescopes within the remaining space under our roll-off roof. These telescopes were so close together that they had to be networked so they would not run into one another. They followed a simple “first into the common space gets to complete its observations” rule. Annual winter conferences at the Lazy K-Bar Ranch near Tucson, summer workshops, many papers, and a number of books [33-40] spread the word on what could be done via full automation and remote access.
With our building fully occupied, the operations at the Fairborn Observatory on Mt. Hopkins steadied out. I wrote a book, Robotic Observatories, with my good friend and astronomer Donald Hayes, that documented much of what been learned in the pioneering 1979-1989 decade at the Fairborn Observatory . It also considered what might unfold in the future for robotic and remotely accessed telescopes—quite prophetically it turned out. There were many other related developments beyond the Fairborn Observatory between 1979 and 1989. These have been described by Alberto Castro-Tirado in his masterful history of robotic observatories .
The robotic telescopes at the Fairborn Observatory on Mt. Hopkins were managed remotely by Principal Astronomers (PAs). Mike Seeds, Sallie Baliunas, and Greg Henry (shown above in his office at Tennessee State University) were early PAs. Greg, who has managed multiple remote telescopes at the Fairborn Observatory for over a quarter of a century, is by far the planet’s most experienced user of robotic telescopes.
The three original robotic telescopes at the rear of the Fairborn Observatory are almost obscured by the four 0.8-meter telescopes that were subsequently added—completely filling up the available space. These seven robotic telescopes observed together harmoniously every clear night on Mt. Hopkins for many years.
The publication of the book Robotic Observatories that I wrote with Donald Hayes marked the end of the pioneering 1979-1989 decade of automated telescope and remotely accessed observatory developments at the Fairborn Observatory. Don was instrumental in many developments and co-authored a number of books with me.
The Later Years
In 1990, I retired from my day job as a Federal laboratory research supervisor. I moved on to other things, and Lou took complete charge as the sole Director of the Fairborn Observatory. When the ten-year agreement between the Fairborn Observatory and the Smithsonian Institution expired, Lou moved the observatory to Camp Washington, a remote, dark site just five miles north of the Mexican border . The original telescopes, such as the Four College APT, continued their operation . No longer constrained by the limited space on Mt. Hopkins, the observatory began to grow. Lou designed a new generation of 0.8-meter photometric telescopes, and four of these telescopes were brought into operation at the Fairborn Observatory including Wolfgang and Amadeus, the University of Vienna’s twin automatic telescopes . In cooperation with Tennessee State University, a 2-meter telescope and automated spectrograph was brought into operation . With the occasional help of Donald Epand writing new software, Lou not only kept all 11 telescopes operating for many years but, as time allowed, started working on additional telescopes. Lou also been worked with Saul Adelman and others on an automated spectrophotometer .
Although William Borucki and I proposed searching for exoplanet transits as early as 1992 , it was not until 1999 that Greg Henry, using a robotic telescope at the Fairborn Observatory, discovered the first transit of an exoplanet. Greg was following up on systems, known via radial velocity measurements to harbor an exoplanet, to see if their spatial alignment would also produce a transit. A number of earlier candidates had not revealed any such transit. Automated photometric measurements of HD 209458 at the Fairborn Observatory on the night of November 7, 1999, caught the first exoplanet transit just before the star disappeared into the western sky .
With continuous operation of multiple robotic telescopes for almost four decades (1983-2021), the Fairborn Observatory and the many books and meetings associated with the observatory and the IAPPP, led the way for many years in the growing automation of astronomical telescopes and observatories.
After 10 years on Mt. Hopkins, the Fairborn Observatory purchased remote dark sky property south of Mt. Hopkins, just 5 miles north of the Mexican border. Operating every clear night is a two-meter automated spectroscopic telescope (left) and an array of smaller telescopes. These 11 robotic telescopes (right) will eventually be supplemented by five additional telescopes now under construction.
Greg Henry, with a robotic telescope at the Fairborn Observatory, observed the first transit of an exoplanet on the night of November 7, 1999. The ingress was caught, but the star was lost in the west before egress.