Measuring asteroids with homemade monsters: using home-built scopes of up to 32 inches, Bob Holmes outdoes most of the world of tracking near-Earth objects. And he's just getting started.
IT'S A STILL SUMMER night at 2 a.m. Insects chirp and drone. Frogs sing. The air is heavy with dew and the smell of cut grass. An occasional breeze rustles the surrounding cornstalks and soybeans and the branches on a few sentinel trees. Farther out across the flat farmland, insecurity lights dot the horizon, some blessedly obscured by the growing crops.
The sky is clear, so Robert E. Holmes, Jr., and his big instruments are busily working.
Dim light glows from a basement window of the nearby house, betraying Bob's lone vigil. Linked to his desk by network cables, a 24-inch f/4.6 and a 32-inch f/4 telescope follow electronic marching orders in their observatory buildings. CCD cameras at the telescopes' prime foci count photons pixel by pixel. The soothing chords of astronomical work--the whirring of drive motors and the clicking of CCD camera shutters--are sometimes audible over nature's chorus.
Only occasionally does a car drive down the country road in front of Bob's office, headlights briefly illuminating the trees and shrubs. Neither the telescopes nor their operator are distracted.
Bob and his wife Jackie used to live near the glow of Charleston, Illinois, close to an over-lit Walmart. In 2009 they moved 12 miles to this new, much darker location--the outcome of an intense, 10-year astronomical saga.
"Twenty years ago," explains Bob, "I left my astronomy hobby for a career as a commercial magazine photographer. I sold my home-built 14-inch Newtonian to finance this venture. It turned out to be an excellent investment--I've had over 4,600 photographs published in magazines in more than 50 countries worldwide."
But in 1999, after picking up an issue of Sky & Telescope in a store, he went to a meeting of the Champaign-Urbana Astronomical Society and then attended a talk by Robert Kirshner at the University of Illinois at Urbana-Champaign. These events rekindled Bob's interest in amateur astronomical research. A commercial 16-inch telescope soon provided his first images and data.
He made two supernova discoveries by repeatedly imaging distant galaxies, and these motivated him to continue farther down the path of imaging for scientific purposes. In 2002 Bob created the not-for-profit Astronomical Research Institute (ARI) to ease the financial burden of running his own observatory, to allow him to apply more easily for grants and donations, and to facilitate outreach to schools, colleges, and students. As he describes it: "The ARI mission was to bring real science directly to the classroom, and provide students with a rewarding handson research project that would demonstrate in a small way the opportunities that are possible by continuing with higher education." He named the 16-inch scope's building the Astronomical Research Observatory (ARO).
By then Bob's main interest had turned from the relatively unproductive task of taking hundreds of images looking for rare supernovae, to the more immediate task of imaging and reporting the positions of asteroids and the occasional comet, especially near-Earth objects (NEOs). The Minor Planet Center in Cambridge, Massachusetts, receives his data; Bob joined hundreds of observatories, amateur and professional, that contribute positions to determine the precise orbits of these objects. The better an orbit is known, the clearer it becomes whether an object poses an impact threat to Earth, the Moon, or another planet.
In particular, the MPC posts a "wish list" of objects needing more position measurements. These include objects that were lost and have to be recovered, objects needing more accurate orbits, and newly discovered objects that need immediate confirmation and tracking.
Bob is particularly dedicated to educational outreach. He shared images and data with other researchers and eager students early on. A pilot program involving a high-school teacher and students in North Carolina in 2006 produced several dozen new asteroids and a few supernovae. But this pushed the 16-inch telescope to its limits. Its relatively long (f/10) focal length meant that, even with a focal reducer, the telescope's field of view was narrow, so it was easy for him to miss his target if the object's position was not precisely known. And 16 inches just wasn't very big. "Making discoveries using the 16-inch reflector became increasingly difficult for students," Bob recalls, "as undiscovered objects became fewer and fainter." Bob decided that a larger instrument was in order.
Building a Bigger Scope
By 2003 he was drawing up the plans for a 32-inch f/4 fork-mounted, truss-tube Newtonian with a CCD camera permanently installed at its prime focus. Such an instrument could image objects fainter than 23rd magnitude, a realm few other amateurs could reach. Small, faint asteroids are far more numerous than larger ones and thus pose a greater impact risk to Earth. Yet even with twice the aperture the new telescope was designed to have a larger imaging field of view, covering more sky in each image. All Bob had to do was build it.
On a shoestring budget, Bob designed and built his 32-inch professional-quality instrument himself, and then later a 24-inch. Luckily, Bob had friends who were up to the task of doing the optical work and machining critical drive components. In his garage shop he used a hand grinder to cut steel plate into telescope parts. He wore out several grinders in the process. He welded the parts for the 32-inch, including its massive fork mount, in the same modest shop, using an engine hoist to move heavy steel assemblies.
He completed the telescope body in 2005. "Installation in the observatory proceeded very smoothly," he says, "and the major telescope components were assembled in just over two hours." But it still lacked a primary mirror. The optical company he paid to do the work proved incapable of it and shipped the mirror back to Bob, at his expense, in a crate that was literally falling apart. The mirror was scratched and badly astigmatic with surface roughness; in other words, unusable.
Another company finished the mirror, and in June 2006 the 32-inch was finally complete. After debugging problems with collimation, the mirror cell, and the coma corrector, the telescope began producing a river of quality data that rivaled larger professional instruments. To this day, Bob regularly hears that his 32-inch scope in a cornfield produces NEO data that rivals or beats that from much larger professional instruments on mountaintops.
Although the temperature, sounds, and environment change with the seasons, Bob's routine became steady after the completion of the 32-inch. Every clear night he began observing at the end of twilight and went to sleep only with the arrival of clouds or dawn. For a year Bob kept this demanding schedule while working days as a photographer. He made his astronomical images available for download by interested high-school and college classes so that students could search for and share in the discovery of new asteroids.
Most objects that Bob images are moving, often rapidly, so accurate pointing and short exposures are necessary. This is what his scopes were built for. An image that successfully captures an elusive object yields valuable position and brightness data. Images are analyzed with software, and the resulting data goes by email to the Minor Planet Center.
In 2007 a NASA grant changed Bob's role from sleep-deprived volunteer to paid, professional data gatherer and observatory operator. He had impressed NASA with the quality, quantity, and reliability of his data to the point that they began to fund it. Bob closed his photography studio to devote himself fully to astronomy.
Not the type to be bored, he filled his free daylight hours building a new, lightweight 24-inch Newtonian, again with a camera permanently at its prime focus. At his former location, he added a second observatory and installed the 24-inch inside it on a Paramount equatorial mount.
Bob now focuses (pun intended) solely on his telescope duties and maintenance, writing grant proposals for new equipment, spending time with his understanding and supportive wife Jackie--and now building a 50-inch telescope to expand his imaging capabilities. Occasionally he sleeps.
If you get to know an unusual and capable person, you often find more that's unusual. Bob used to build model airplanes and rockets capable of reaching hundreds of miles per hour. With some construction background, Bob built all of his observatory buildings himself from the ground up, fast and cheap. At his current location he built the three observatory buildings pictured on the next page and recently completed a larger fourth for the 50-inch.
In 2008, Bob's old observatory near the lights of town produced 11,593 observations of asteroids and NEOs accepted by the Minor Planet Center (MPC). This was more than any other individual or professional observatory (most of which had larger instruments) in the world that year. In 2009 he produced 7,893 observations while also working to move to his new location.
Bob explains: "One advantage of the Midwestern location are the observations we make during the summer months, when the Southwestern observatories are closed due to the monsoon season. In the summer of 2011, ARO worked 66 out of 75 nights, producing more than 2,200 NEO measures and confirming hundreds of potentially new NEO discoveries made by PanSTARRS," one of the next generation of giant professional sky surveys. "During the same time period all other observatories in the entire U.S. made just over 1,250 measures--including PanSTARRS."
He made nearly all his early observations from an altitude of 721 feet less than a mile from a badly overlit apartment complex and a Walmart parking lot striving for permanent daylight. In one direction down the street, a neighbor had bright lights that would occasionally interfere with scientific work. In the other direction, every night an inconsiderate church shone a parking lot spotlight directly at Bob's house, casting shadows on his property from a distance of a quarter mile, despite Bob's repeated requests for it to be re-aimed or replaced.
Under these conditions Bob produced data accepted by the MPC for objects as faint as magnitude 23.7, and he imaged stars fainter than that. The telescope was carefully baffled against stray light, and the interior of the observatory was painted a dark color.
Bob and Jackie's new 40-acre tract, all their own, has meant not only more room for observatories but a larger buffer zone between them and neighbors' lights.
The property already had a house. The relatively lightweight 24-inch telescope was easily disassembled and moved. The 32-inch required a crane to lift parts out of the old observatory and onto trucks. After everything was reassembled, realigned, and rewired, in November 2009 Bob resumed observations under a new MPC observatory code: H21. Only after the telescopes came back to life did the couple complete the move of their household!
Even prior to the move, however, Bob had begun an ambitious new project: a 50-inch scope, to increase productivity. Next to the other two new observatories he staked out a site for its building. But first came a third, smaller observatory. This one houses a donated 30-inch instrument that is mostly run by students via the internet. Modernizing and debugging the drive system took more time and work than expected, but the 30-inch came online in 2010.
Bob then devoted his "spare" time to the 50-inch project. A huge fork mount rose from a pile of metal in his shop. The base of the mount was next. As of this writing, most of the telescope is complete except for the primary mirror itself.
Only the Start
"From the very beginning education and public outreach has been an important element of our research." Holmes insists. "Putting current data in the hands of teachers and students directly in the classroom continues to be a major focus. Each night we work, about 3 gigabytes of images are uploaded to our FTP site for student researchers less than 12 hours after acquisition. Through our work in NASA education and public outreach programs, we reach about 300 schools in 40 countries each year."
He continues: "I think what sets ARO apart from most other observatories is our passion for the science. When we were told that the telescopes we were using were simply not large enough for NEO observations, we built our own from scratch. When the site was no longer dark enough for faint observations, we moved all our instrumentation and built new observatories to produce the best observations that we possibly can in the Midwest."
Based on past experience, Bob won't stop until the new 50-inch is performing superbly, and then he will start planning some new instrument or endeavor, which will cost him even more sleep... and so goes the life astronomic on the Holmes telescope farm. ?
Professional optician Mike Lockwood manufactures large telescope optics and made the mirrors for Holmes's big scopes.
Position Measures of Faint Near-Earth Objects in 2010 Observatory Max. aperture Measurements Magdalena Obs. 2.4m 2,907 David Tholen team 2.2m 621 Mark Trueblood 2.1m 292 Spacewatch II 1.8m 5,406 PanSTARRS 1.8m 779 Mt. Lemmon 1.5m 7,109 Spacewatch I 0.9m 1,510 Tenagra II 0.81m 2,187 Robert Holmes/ARO 0.81m 11,492 WISE Space Telescope 0.41m 10,360
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|Title Annotation:||Amateur Achievements|
|Publication:||Sky & Telescope|
|Date:||Dec 1, 2011|
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