From ESOblog (EU): “Paranal Perspectives”

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From ESOblog (EU)

23 April 2021

Gerhard Hüdepohl

Home to ESO’s Very Large Telescope (VLT), Paranal Observatory in Chile’s Atacama Desert has been at the forefront of astronomical research since its inauguration in 1999.

Over the years, it has earned a reputation as one of the best observing sites in the world. To find out more about its evolution, we spoke to Gerhard Hüdepohl, who documented his time as an engineer at Paranal through some spectacular photography.

“I still have it here, on my shelf!” Gerhard holds up his Praktica, a purely mechanical reflex camera that he was given by his father at the age of fifteen. “It still sort of works. I wouldn’t bet that it still exposes correctly, but it’s a nice memory to have.”

When his father bought himself a new camera, giving Gerhard his old Praktica, it was the start of a life-long passion. “From there on I was hooked,” he says. “From my father, who developed his own film at home, and with friends, I continued to learn and improve. It’s been a never-ending process ever since.”

Gerhard took photographs whenever he could. After studying electronic engineering at university, he worked as a commissioning engineer in several countries, including China, Australia, and South Korea, providing plenty of chances for inspiration. His first time in Chile, however, was as a tourist. It was on this trip that he caught his first glimpse of ESO, in the form of La Silla — the oldest of ESO’s observatories.

“I was in Chile in ’94”, he recalls, “on a bus to the north. From the window I saw La Silla, and I remember thinking, ‘wow, that’s somewhere I would like to work.’ These huge telescopes that were used to understand the secrets of the stars really caught my attention.”

Construction of the VLT at ESO’s Paranal Observatory, 500 kilometres north of La Silla, began in 1991, but it wasn’t until the majority of concrete and steel work was complete that opportunities arose for electronic engineers. From Malaysia, where he was working at the time, Gerhard applied to work for ESO.

“Although I always had an interest in the Universe, I think I was more interested in these giant, perfect machines than in astronomy. These telescopes have the weight and size of a ship, but have to work to a precision of within a few thousandths of a milimetre. I find that fascinating”. [1]

The early days of Paranal

“I joined ESO in 1995, and in my first years I was working as part of the Assembly, Integration and Verification team of the VLT,” says Gerhard. “The priority was to reach the first light on schedule.”

At a time when the telescopes were still under construction, the atmosphere at Paranal was unique. The Residencia — the futuristic-looking lodge where ESO staff now reside when working on-site — had not been built yet, so everyone was living in the adjacent basecamp. And in this early stage of construction, priorities could change at short notice.

The long, facade opens towards the Pacific Ocean and provides a great view of the colourful sunset. The terrace in the middle is part of the Cantine Area but can only be used when the wind is not too strong. Credit: Gerd Hüdepohl (

“Living and working together, in such an isolated location, really welds the team together. You depend on each other, and there’s no escape. It’s a little bit like being on a ship in the middle of the ocean — if you don’t row together, the ship won’t go anywhere.”

One of the most important milestones for Paranal was the first light of the VLT’s Unit Telescope 1, Antu, in 1998. Unsurprisingly, this was one of Gerhard’s most memorable moments from his time at the observatory.

“Late one evening, after many months of assembling and testing the telescope, we opened the large observing slit doors of Antu’s dome for the first time, and pointed the telescope to the stars.

This huge telescope moved silently around its axes to the sky. That moment I will never forget.”

The almost-finished dome of UT1 (Antu) stands next to the empty steel frame of UT2 (Kueyen). Credit: G.Hüdepohl (

Engineers inside the dome of UT3 (Melipal) watch carefully as a crane lifts down the top ring of the telescope. Credit: G.Hüdepohl (

This image was taken when the UT4 telescope (Yepun) was still under construction. The golden evening sky can be seen through the empty skeleton of the dome. Cerro Armazones, home of the future Extremely Large Telescope, can be seen in the horizon. Credit:
G.Hüdepohl (

La Residencia

Inaugurated in 2002, La Residencia at ESO’s Paranal Observatory provides a welcome retreat from the harsh environment of the Atacama Desert. When you work in one of the driest places on Earth, the humidity provided by the oasis under the Residencia’s dome is a much-needed relief.

“It was really nice to have a permanent room there,” says Gerhard. “As well as a gym and a swimming pool!”

The Residencia has also welcomed guests beyond the engineers and astronomers working on site. Its exterior was featured in the 2008 James Bond film, Quantum of Solace.

Gerhard was at Paranal during the filming, and had the fortunate opportunity to be involved in some behind-the-scenes work. “Below Paranal there is a small airstrip which was used in a scene, and they required some planes for decoration. At the time I had a pilot’s license, so I flew a small plane in from Antofagasta, which appears in the movie for a few seconds!

This marvellous aerial photograph of the home of ESO’s Very Large Telescope (VLT), fully demonstrates the superb quality of the observing site. In the foreground we see the Paranal Observatory, located at an altitude of 2,600 metres on mount Paranal in Chile. In the background we can see the snow-capped, 6,720 meter-high volcano Llullaillaco, located a mind-boggling 190 km further East on the Argentinean border. This image is a testimony of the magnificent quality of the air and the ideal conditions for observing at this remote site.

Clearly visible in the image are the domes of the four giant 8.2-metre Unit Telescopes of the VLT, with the Control Building, where astronomers carry out the observations, in the foreground. Taken several years ago, this photograph does not show the Auxiliary Telescopes nor the dome of the soon to come VST Survey Telescope. Credit: /G.Hüdepohl ( ESO.

Different views of Paranal

Gerhard’s pilot’s license came in handy on more occasions than the filming of Quantum of Solace. Several of his Paranal photographs, many of which can be found on the ESO image archive, were taken from the air.

“One of my favourite photos, a very old one, shows Paranal in front of a snow-covered Llullaillaco”. The world’s highest historically active volcano, Llullaillaco, lies on the border between Chile and Argentina. On clear days, it can be seen from ESO’s Paranal Observatory.

“There was a day when I happened to fly, when it had recently snowed, and when the skies were very clear. I got this picture, taken on film. I’ve tried several times to repeat this picture on digital, but could never get it exactly right.”

“But I think my favourite photo is one I took with a drone, between the four laser beams of Yepun,” he says, referring to the VLT’s Unit Telescope 4. “It took quite some preparation, and several attempts, to get the image I had in mind.”

Twinkling stars are far more desirable to poets and romantics than to astronomers. Even in the near-pristine seeing conditions over Chile, home to ESO’s fleet of world-class telescopes, turbulence in Earth’s atmosphere causes stars to twinkle, blurring our view of the night sky.

These four laser beams are specially designed to combat this turbulence. The intense orange beams dominating this image originate from the 4 Laser Guide Star Facility, a state-of-the-art component of the Adaptive Optics Facility of ESO’s Very Large Telescope (VLT). Each beam is some 4000 times more powerful than a standard laser pointer! Each creates an artificial guide star by exciting sodium atoms high in the Earth’s upper atmosphere and causing them to glow.

Creating artificial guide stars allows astronomers to measure and correct for atmospheric distortion, by adjusting and calibrating the settings of their observing equipment to be as accurate as possible for that particular area of sky. This gives the VLT a crystal-clear view of the cosmos, so it can capture the wonders of the Universe in stunning detail.

This amazing capture was taken using a drone flown over the VLT by ESO Photo Ambassador Gerhard Hüdepohl. Credit: G. Hüdepohl (

These lasers create four artificial “stars” high up in the atmosphere, which are then used to measure and correct the atmospheric turbulence, allowing the telescope to capture crisp images. To take this stunning shot, Gerhard had only a time slot of around ten minutes when it was dark enough to see the lasers, yet light enough for the surrounding desert to be visible. After many attempts, Gerhard captured this spectacular image, which was featured in the National Geographic magazine. “For a photographer, this is something like the Oscars!”

What’s next for Paranal?

Another memorable moment from my time at ESO was during 2019, my last year”, Gerhard describes. “I was able to follow the first part of the construction of the ELT. At one moment, I realised that this stage of construction I was seeing was roughly the same as that of Paranal, when I first started working there. For me, it closed a cycle.

The first evening of the new year was beckoned in by a spectacular supermoon, rising up from behind the majestic Cerro Armazones mountain in Chile. A supermoon like this is a magnificent, albeit relatively frequent, occurrence which takes place when a full moon coincides with the point in the lunar orbit that is closest to Earth, its diameter appearing about 14% larger in the sky.

The road zigzagging up Cerro Armazones appears to lead directly to the Moon itself — truly making it a road to the stars. By 2024, the “world’s biggest eye on the sky” will rest on top of this mountain, as its peak will be home to the Extremely Large Telescope. At an altitude of 3046 metres, Cerro Armazones provides a spectacular environment for astronomical observations, in particular because it receives 320 clear nights per year.

This photo was captured by ESO Photo Ambassador Gerhard Hüdepohl. He walked two kilometres from ESO’s nearby Paranal Observatory into the Atacama Desert to find the right position to take this photo. Beforehand, he had calculated the path the Moon would take to know the right time and place for this extraordinary shot. Credit: G.Hüdepohl (

At Cerro Armazones, just 25 kilometres from Paranal, ESO is building the Extremely Large Telescope (ELT).

As the largest infrared and visible light telescope in the world, the ELT will be revolutionary for astronomy. However, it is by no means the end of Paranal’s story. An exciting host of upcoming instruments, as well as upgrades to existing infrastructure, will open up new windows to continue studying the universe from Paranal. Moreover, the ELT will be operated from Paranal as well.

Extremely large astronomy
The era of extremely large telescopes is beginning — and it will revolutionise our understanding of the Universe. ESO’s Extremely Large Telescope (ELT) is currently under construction in the remote Chilean Atacama Desert; this groundbreaking telescope alone will collect more light than over 200 NASA/ESA Hubble Space Telescopes.

As the name suggests, such telescopes are truly colossal. The largest primary mirrors — by which a telescope collects light — currently in operation at all of ESO’s sites are the 8.2-metre-diameter mirrors in the four Unit Telescopes comprising the Very Large Telescope (VLT). The ELT will dwarf the already impressive VLT with its vast mirror at 39 metres in diameter! However, constructing a single, science-quality mirror of such a size is simply not possible — the ELT’s primary mirror will, in fact, be a complex honeycomb arrangement of 798 tessellated hexagonal 1.4-metre mirrors.

Finding a suitable place for such a structure was also no easy task. As well as requiring the dry and light-pollution-free conditions at a high altitude necessary for successful astronomy, the ELT needed a huge space on which to spread its foundations. As such a location was not available, it was created! The complex journey of the ELT’s construction began by flattening the top of the Cerro Armazones mountain in Chile, taking 18 metres off its full height. That site is now covered by a web of foundations — as seen in this image. Credit: G. Hüdepohl/ESO.


[1] The movable structure of each VLT Unit Telescope weighs about 430 tonnes and is so well-balanced and well-oiled that it can be moved by hand.

See the full article here .


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ESO (EU) is the foremost intergovernmental astronomy organisation in Europe and the world’s most productive ground-based astronomical observatory by far. It is supported by 16 countries: Austria, Belgium, Brazil, the Czech Republic, Denmark, France, Finland, Germany, Italy, the Netherlands, Poland, Portugal, Spain, Sweden, Switzerland and the United Kingdom, along with the host state of Chile. ESO carries out an ambitious programme focused on the design, construction and operation of powerful ground-based observing facilities enabling astronomers to make important scientific discoveries. ESO also plays a leading role in promoting and organising cooperation in astronomical research. ESO operates three unique world-class observing sites in Chile: La Silla, Paranal and Chajnantor. At Paranal, ESO operates the Very Large Telescope, the world’s most advanced visible-light astronomical observatory and two survey telescopes. VISTA works in the infrared and is the world’s largest survey telescope and the VLT Survey Telescope is the largest telescope designed to exclusively survey the skies in visible light. ESO is a major partner in ALMA, the largest astronomical project in existence. And on Cerro Armazones, close to Paranal, ESO is building the 39-metre European Extremely Large Telescope, the E-ELT, which will become “the world’s biggest eye on the sky”.

European Southern Observatory(EU)/MPG Institute for Radio Astronomy [MPG Institut für Radioastronomie](DE) ESO’s Atacama Pathfinder Experiment(CL) high on the Chajnantor plateau in Chile’s Atacama region, at an altitude of over 4,800 m (15,700 ft).