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Amateur-astronomer Philip Corneille FRAS visited over 150 observatories in 33 countries to collect historical & technical data of telescopes and astronomical instruments.

During a recent lecture on my tour of observatories in Australia, the question popped on the number of astronomical observatories I already had visited. Checking my records I found to my astonishment that, during the last 4 decades I had visited over 150 sites in 33 countries. Consequently it was long overdue to write an article about the people who offered me an in-depth look at the optics and instruments that make astronomy the most exciting science, fascinating audiences worldwide.

Basic astronomy lessons about the Sun and the Moon were part of the Belgian national curriculum taught in elementary school so my obsession with the night sky started as a schoolboy eager to learn more about astronomy and telescopes. During the 1970s, further interest was sparked by the TV programs presented by the late astronomers Sir Patrick Moore (1923-2012) in "The Sky At Night" and Carl Sagan (1934-1996) in "Cosmos". In both programs, these brilliant communicators visited observatories all over the globe, and I got inspired to visit those remarkable places which serve as windows to the Universe and where important astrohistory was made.
As an amateur-astronomer and novice astrophotographer, it seemed logical to visit professional astronomical sites, which were after all carefully selected for their dark or radio-silence location. Moreover, some observatories offer open nights to the public, a great opportunity to observe the planets through larger and often historical telescopes. Nature lovers definitely will get their money's worth of hiking up to an astronomical observatory as few sites rival the beautiful remote natural locations of telescope domes, often described as jewels on mountaintops. At night, visitors enjoy the amazing sight of the Milky Way in a pitch-dark night sky and can reflect on the immensity of universal nature.
In the 1980s I started to visit the well-known sites among which the Palomar observatory (California), McDonald Observatory (Texas) and the Kitt Peak National Observatory (Arizona). The latter is the most visited astronomical observatory site in the continental USA, perhaps even in the world, giving the general public a good indication of the great diversity in telescopes used in modern astronomy. Mount Wilson in the San Gabriel mountains of California is my favorite US observatory as it breathes history with, on the one hand, solar towers and on the other the 60- and 100-inch reflectors, which enabled Edwin Hubble to discover the expanding Universe. Visitors of this legendary observatory can almost smell astrohistory by seeing Hubble's personal locker or taking a look at the fascinating collection of books in the library of the monastery building. In the cold 33m high steel dome, individuals get a sense of how difficult it must have been to manually track extragalactic nebulae during long nights of painstaking observations in order to measure redshifts. You get a sense of the discomfort and one nevers forgets the smell of the place or the sight of the copper handles and push buttons of the dome drive system. Moreover, members of the general public can experience the thrill of observing with these century old reflectors, an activity which grows in popularity as Mt Wilson will be celebrating some upcoming centaneries, such as first light 100-inch (November 1917) and the Great Debate of April 1920.
In the 1990s, the work of ground based observatories was overshadowed by the success of the Hubble Space Telescope, making headline news with superlative (brightest, most distant) findings. However, in October 1995, the discovery of the first extra-solar planet around a Sunlike star renewed worldwide interest in the work of small telescopes. Moreover, exoplanetary research became the most exciting and fastest-growing field in astrophysics as it might answer the fundamental question if there's life beyond the solar system. During my travels I've tried to focus on the ingenuity and resourcefulness of young astronomers using small instruments to detect signs of exoplanets. Moreover, computer technology, running sophisticated software, plays an increasingly large role in these "small" projects, such as Super-WASP (Wide Angle Search for Planets) and HATnet (Hungarian-made Automated Telescope network). Both projects have observatories in both hemispheres and use off-the shelf f/1.8 photo lenses to monitor large parts of the sky in order to detect periodically dimming of stars, which might indicate an exoplanet transit signal. The photometric system functioned properly and in the case of super-WASP, the expansion lead to a search for additional "paparazzi" photo lenses on auction websites as these were no longer available.

Such telescopes can ideally serve as workhorses in the detection and follow-up observations of Earth-approaching asteroids and comets. Observations spanning several nights allow astronomers to compute the orbit of a Potentially Hazardous Asteroid (PHA). International observation programs, which have a high degree of continuity performed by both professional and amateur-astronomers, are coordinated through the Minor Planet Center (MPC - Harvard College Observatory). Finding and tracking Near-Earth Asteroids (NEA) appeals to the imagination and I was lucky to see two protagonists at work in this field of astronomical research; Robert McNaught (Siding Spring, Australia) and Korado Korlevic (Visnjan, Croatia).
Both astronomers showed a high degree of motivation and dedication to continue their work, even though there were little or no budgets available at the time. They had a great willingness to help other astronomers in the follow-up of certain objects and kept track with all advances in their field of research. After each visit, I had a convincing sense that their persisting work was a personal source of intense satisfaction and accomplishment for both men.
The use of "small" telescopes in extragalactic research can be illustrated by the compelling stories of the Sloan Digital Sky Survey (SDSS) and its counterpart in the Southern hemisphere, the Skymapper project. Both projects use a dedicated reflector (2.50 m SDSS at Apache Point, USA and 1.35 m Skymapper at Siding Spring, Australia) equiped with a tiled mosaic of Charge-Coupled Devices (CCD - electronic detectors) supported by powerful image-detection technology controlled by software to observe, record and archive all scientific data. Engineers can talk endlessly about the satisfaction of tackling problems ranging from a broken secundary mirror, the proper adjustment of the optics or even removing 50 kilograms of ladybird beetles from the dome's drive system. During my May 2008 visit to SDSS, periods of light snow were a gentle reminder that the weather can be an annoyance at all times in the year. Both projects will produce three-dimensional maps of the structure of the universe in order to map its expansion rate to 10 billion light years and beyond.
The professional astronomer's day starts in late afternoon, visiting the dome in order to check the instruments with the day crew and telescope operator. After dinner in the evening, the astronomers join the high tech environment of the control room to start and monitor their observation sequence. After a few hours they might enjoy a "midnight lunch" while their observations continu. Their observating run ends at dawn and after checking their data, the astronomers rejoin the sleeping quarters. Depending on the project, they get between one and three nights of observing time. Of course, solar observers and radio astronomers can work during daylight, providing it doesn't rain too hard. During my visit of the 64 m radio dish in Parkes - Australia, I witnessed the procedure of writing the names of everybody who climbed the narrow support tower on a large billboard, so technicians can check who went up the dish, before moving the 1000 tonnes radio telescope.
Visiting large professional optical telescopes (4 m class) is a totally different story as the usage of these oversubscribed telescopes is fixed six months in advance. Observatories with many telescopes are a bonus but each unit is under a different administration, so planning a tour requires some paper work. Moreover, visits preferably take place during full moon as moonlight pollutes the night sky and technicians take the opportunity to do maintenance or plan recoating of the mirrors. A behind the scenes look is always interesting as it's great to see how engineers tackled problems and developed compact optimised cylindrical enclosures which can windspeeds of 200 km/hour. The development of active optics (hydraulic supports to maintain the optimal shape of the main mirror) and LASER adaptive optics (computer-controlled deformable secondary mirror to descramble seeing-distorted starlight) was crucial for the development of a new generation of 10 m class telescopes.
Over the years, telescope managers have recognized the need to cooperate with peer-observatories in order to deliver cutting-edge astronomy. The costs and technological challenges to design, develop and test the next generation of 30 m class telescopes will require even more ambitious multi-institutional partnerships. Personally I have seen that this cooperation is already bearing fruit in the preparations for the Giant Magellan Telescope at the Advanced Instrumentation & Technology Center at Mt Stromlo, Australia and at the new head quarter of the European Southern Observatory (ESO) in Germany. At the latter, European teams are working on the mirror segments for the 40 m class European Extremely Large Telescope (E-ELT) and were glad to share experiences with their American colleagues who're working on the segments for the Thirty Meter Telescope (TMT). These behemoth reflectors will have a segmented main mirror consisting of 492 and 798 hexagonal segments with reserve segments so the telescope can operate continuously, ushering a new era of astronomical discoveries.

From the Uppsala Gamla Observatory in Sweden to the South African Astronomical Observatory (SAAO) near Sutherland in the Northern Cape province, I always enjoyed a warm welcome and was mesmerized by the enthusiasm of astronomers and technical staff alike. Getting access to some observatories can be undeniably very difficult (e.g. my dream destination the South Pole) and at some sites I was escorted by security personnel or park rangers. At night, I sometimes accompanied astronomers who ventured outside to photograph or observe the night sky with their personal equipment. I also learned that music plays an important role in keeping telescope operators awake as they might start an observing run with classical music but switch to rock music as the night progresses. Remarkably, occasionally there's a recurring theme that catches a visitor's attention, like the resourcefulness to make a finder scope or an eyecatching piece of furniture. The basic but suitable wooden Thonet chair found in the domes and workshops of Lick, Mt Wilson and Yerkes seems a personal touch by George Willis Ritchey, who was the son of an Irish cabinet maker. While spending a few days in the daily life of professional astronomers gets the visitor to some special areas, such as the open air swimming pool at the Haute Provence Observatory (OHP - France) or botanical gardens associated with some observatories in cooperation with other science branches. Managers have also been thinking out-of-the-box and it's great to know that the finacial burdens threathening the 3.8 m UKIRT (Hawaii), the 3.0 m Shane reflector (Lick, California) and some telescopes at Kitt Peak have been resolved.
During the International Year of Astronomy (IYA 2009), the European Southern Observatory (ESO) used some of my technical data on their decommissioned telescopes in the appendix 1 of their excellent anniversary book "Europe to the Stars — ESO’s first 50 years of exploring the southern sky". A feat that got me elected Fellow of the Royal Astronomical Society, a great honor for any amateur-astronomer.
Last but not least I would like to mention the "Astronomers without borders", an organization I have seen at work during my travels. This worldwide community donates telescopes and supports secondary schools while sharing the wonders of the Universe and capturing the imagination of youngsters without political, geographic or cultural borders. It's one of the most enjoyable and rewarding aspects of astronomy.
Anno 2015, we live in a golden era of astrophysical discoveries, ranging from primitive bodies in the outer solar system to Earthlike exoplanets orbiting other stars. I was very priviliged to see professional astronomers at work and meet an engaged staff or group of volunteers, so if you get the chance to visit an observatory, by all means go!

Photos: https://www.flickr.com/photos/72473941@N03/