Picture of the Week

24 September 2012

A Hard Day's Night Ahead

Sunset is typically a sign that another working day is over. City lights are slowly switched on as people return home eager to enjoy the evening and a good night’s sleep. However, this does not apply to astronomers working at an observatory such as ESO’s Paranal Observatory in Chile. Observing starts as soon as the Sun has disappeared below the horizon. Everything needs to be ready before dusk.

This panoramic photograph captures the ESO Very Large Telescope (VLT) against a beautiful twilight on Cerro Paranal. The enclosures of the VLT stand out in the picture as the telescopes in them are readied for a night of studying the Universe. The VLT is the world’s most powerful advanced optical telescope, consisting of four Unit Telescopes with primary mirrors 8.2 metres in diameter and four movable 1.8-metre Auxiliary Telescopes (ATs), which can be seen in the left corner of the image.

The telescopes can also work together as a single giant telescope, the ESO Very Large Telescope Interferometer (VLTI), which allows astronomers to observe the finest possible detail. This configuration is only used for a limited number of nights per year. Most of the time, the 8.2-metre Unit Telescopes are used individually.

Over the past 13 years, the VLT has had a huge impact on observational astronomy. With the advent of the VLT, the European astronomical community has experienced a new age of discoveries, most notably, the tracking of the stars orbiting the Milky Way’s central black hole and the first image of an extrasolar planet, which are two of the top three of ESO’s Top 10 Astronomical Discoveries.

The VLT’s four Unit Telescopes are named after celestial objects in Mapuche, which is an ancient native language of the indigenous people of Chile and Argentina. From left to right, we have Antu (UT1; the Sun), Kueyen (UT2; the Moon), Melipal (UT3; the Southern Cross) and Yepun (UT4; Venus).

This photograph was taken by ESO Photo Ambassador, Babak Tafreshi.

This image is available as a Mounted Image in the ESOshop.

#L


17 September 2012

ALMA and a Starry Night — a Joy to Behold

A crystal-clear sky on any night is always a joy to behold. But if you are on the Chajnantor Plateau, at 5000 metres altitude in the Chilean Andes and one of the best places in the world for astronomical observations, it could be an experience that you’ll remember for your whole life.

This panoramic view of Chajnantor shows the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) against a breathtaking starry night sky.

In the foreground, we can see some of ALMA’s antennas, working together. The plateau appears curved, because of the effect of the wide-angle lens used. ALMA is the world’s most powerful telescope for studying the Universe at submillimetre and millimetre wavelengths. Construction work for ALMA will be completed in 2013, and a total of 66 of these high-precision antennas will be operating on the site. At the moment, the telescope is in its initial phase of Early Science Observations. Even though it is not fully constructed, the telescope is already producing outstanding results, outperforming all other submillimetre arrays.

In the sky above the antennas, countless stars shine like distant jewels. Two other familiar celestial objects also stand out. First, the image is crowned by the Moon. Second, outshone by the glow of the Moon, it is possible to distinguish the Milky Way as a hazy stripe across the sky. Dark regions within the band are areas where the light from background stars is blocked by interstellar dust.

This photograph was taken by ESO Photo Ambassador, Babak Tafreshi. Babak is founder and leader of The World At Night, an international project to produce and exhibit a collection of stunning photographs and time-lapse videos of the world’s landmarks with a backdrop of the most beautiful celestial wonders.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links


10 September 2012

A Timeless Sanctuary in Santiago — The ESO Guesthouse, Then and Now

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO facilities in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

This month, we are showing a part of ESO that feels almost timeless. After a long intercontinental flight to Santiago, or the night-shifts of an observing run at the telescopes, what could be better than a comfortable staging post at which to recover and rest before the next part of the journey? From the organisation’s earliest years, ESO’s Guesthouse in Santiago has provided just this for visitors to the observatory’s sites in Chile. Our Then and Now photographs this month show the guesthouse lounge, in 1996 and the present day.

The guesthouse is a large villa in a quiet part of the Chilean capital. It is renowned among ESO staff and visiting astronomers as a welcome and inviting rest stop on the long journey between Europe and the remote observatory sites. Almost all European astronomers visiting La Silla, Paranal, or Chajnantor are likely to pass through the guesthouse. Here they can recover from the journey, converse with fellow astronomers, prepare for their observation run and — for newcomers — perhaps get their first glimpse of the southern night sky.

It was decided as early as 1964, with the ESO activity increasing in Santiago, to acquire a pied à terre in the city so that ESO would not have to rely on hotels. The purchase of the guesthouse was completed in March 1965, and it was originally used as an administration office as well as a lodge for visitors. However, in the early 1970s the official ESO offices were moved to the new building in Vitacura, a few kilometres away in the city, allowing the guesthouse to be used exclusively for the comfort and convenience of travel-weary astronomers and other staff.

As can be seen in these two photographs, the guesthouse has not changed much over the years. Wireless internet is now available, and a more modern coffee machine has been provided, but the guesthouse remains a relaxed and peaceful sanctuary. The perfect place to unwind and prepare for gruelling yet exciting nights of observations, and perhaps for the next big discovery.

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3 September 2012

A Surprising Superbubble

This colourful new view shows the star-forming region LHA 120-N44 [1] in the Large Magellanic Cloud, a small satellite galaxy of the Milky Way. This picture combines the view in visible light from the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile with images in infrared light and X-rays from orbiting satellite observatories.

At the centre of this very rich region of gas, dust and young stars lies the star cluster NGC 1929. Its massive stars produce intense radiation, expel matter at high speeds as stellar winds, and race through their short but brilliant lives to explode as supernovae. The winds and supernova shock waves have carved out a huge cavity, called a superbubble, in the surrounding gas.

Observations with NASA's Chandra X-ray Observatory (shown here in blue) reveal hot regions created by these winds and shocks, while infrared data from NASA's Spitzer Space Telescope (shown in red) outline where the dust and cooler gas are found. The visible-light view from the MPG/ESO 2.2-metre telescope (in yellow) completes the picture and shows the hot young stars themselves as well as the glowing clouds of gas and dust that surround them.

Combining these different views of this dramatic region has allowed astronomers to solve a mystery: why are N44, and similar superbubbles, giving off such strong X-rays? The answer seems to be that there are two extra sources of bright X-ray emission: supernova shock waves striking the walls of the cavities, and hot material evaporating from the cavity walls. This X-ray emission from the edge of the superbubble shows up clearly in the picture.

Links

Notes

[1] The designation of this object indicates that it was included in the Catalogue of H-alpha emission stars and nebulae in the Magellanic Clouds, compiled and published in 1956 by American astronomer–astronaut Karl Henize (1926–1993). The letter “N” indicates that it is a nebula. The object is often called simply N44.


27 August 2012

Night Comes to Paranal

Imagine that you have just watched a beautiful sunset from the top of Cerro Paranal. As the Atacama Desert silently fades into the night, ESO’s Very Large Telescope (VLT) opens its powerful eyes on the Universe. With this spectacular 360-degree panorama, you can imagine the view that you would have if you were standing there, near the southern edge of the VLT’s platform.

In the foreground, the fourth of the VLT’s Auxiliary Telescopes (AT4) is opening. To its left, the Sun has already set over the Pacific Ocean — covered by clouds below the altitude of Paranal, as usual. Across the rest of the platform, the other three Auxiliary Telescopes are seen in front of the large buildings of the four 8.2-metre Unit Telescopes. Finally, the Residencia and other basecamp facilities are also visible a little distance away, near the right-hand edge of the picture.

As the night begins, imagine that you are immersed in a deep silence, barely interrupted by the wind or by the smooth movement of these giant machines. It is hard to believe that intense activity is going on in the VLT Control Building, located on the slope of the mountain just below the level of the platform, in the direction of the setting Sun. There, astronomers and telescope operators are starting the first observations of the night. 

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20 August 2012

Laser Guide Star Sweeps Across a Starry Sky

A powerful laser beam from ESO’s Very Large Telescope (VLT) paints the night sky over the Chilean Atacama Desert in this stunning image taken by Julien Girard. The Earth’s rotation during the 30-minute exposure — and the movement of the laser as it compensated for this — is why the beam appears to fan out. This is also why the stars are stretched into curved trails, revealing subtle differences in their colours.

The laser is used to create a point of light — an artificial star — by making sodium atoms 90 kilometres up in the Earth’s atmosphere glow. Measurements of this so-called guide star are used to correct for the blurring effect of the atmosphere in astronomical observations — a technique known as adaptive optics. While sufficiently bright natural stars are also used for adaptive optics, a laser guide star can be positioned wherever it is needed, meaning that adaptive optics can be used for targets across more of the sky.

The four large enclosures of the VLT’s 8.2-metre Unit Telescopes are visible in the photograph, with the smaller VLT Survey Telescope (VST) in the background. Julien is an ESO astronomer based in Chile, who works at the VLT. On the night this photo was taken, he was supporting observations on the rightmost Unit Telescope, and took the opportunity to set up his camera on a fixed tripod before returning to the control building to make the observations.

The movements of the telescope enclosures during the long exposure also appear as a blur, while faint trails of light, made by people walking across the platform between the telescopes, can also be seen.

Julien submitted this photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

Links


13 August 2012

Orion Watching Over ALMA

Standing watch over the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), Orion, the Hunter, shines high in the Chilean night sky. With its distinctive hourglass shape and the three bright stars of Orion’s Belt in the centre, the constellation is easily recognisable. Taken from the southern hemisphere, this image shows Orion’s sword above the Belt. The sword is home to one of the most stunning features of the sky — the Orion Nebula — which appears as the middle “star” in the sword, its fuzzy nebulosity visible to the naked eye under good conditions.

The three ALMA antennas visible in the image represent only a small part of the complete ALMA array, which has a total of 66 antennas. ALMA combines the signals from its antennas, separated over distances of up to 16 kilometres, to form a single giant telescope, using a technique called interferometry. While construction is not due to be completed until 2013, early scientific observations began with a partial set of antennas late in 2011.

At 5000 metres altitude on the Chajnantor Plateau in the foothills of the Chilean Andes, in one of the most arid regions in the world, ALMA is guaranteed outstanding observing conditions. A high, dry site such as Chajnantor is needed because water vapour and oxygen in the Earth’s atmosphere strongly absorb the millimetre and submillimetre wavelengths of light at which ALMA is designed to observe.

In this photograph, the antennas were being tested at ALMA’s Operations Support Facility, located at the slightly lower altitude of 2900 metres. Once tested and fully equipped, they were transported up to the Chajnantor plateau to begin their work.

This image was taken by Adrian Russell, who submitted the photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

Links


6 August 2012

From a Dirt Track to the World’s Leading Observatory

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

This pair of pictures shows a view from the entrance of the Paranal Observatory site in northern Chile, looking towards the summit of Cerro Paranal, as seen in 1987 and in the present day.

The Cerro Paranal region was first scouted out as a possible site for the future Very Large Telescope (VLT) in 1983 by a team including ESO’s Director General at that time, Lodewijk Woltjer (see The Messenger, No. 64, pp 5–8 for more information). In 1987 a dirt road to the summit was constructed and a permanent station for monitoring the conditions was established. The historical picture shows the view at that time.

The site testing results were extremely good — the conditions were clearly better than either ESO’s La Silla Observatory or the other sites then under consideration. They led to the decision to site the VLT on Paranal, which was made by the ESO Council in December 1990 (see eso9015).

Much has changed at Paranal in the 25 years since the historical photograph was taken. The summit of the mountain was leveled and a high-quality road put in place, and of course the observatory’s telescopes themselves were constructed. The complete and fully operational observatory can be seen in the present day photograph. On the summit now stand the four 8.2-metre VLT Unit Telescopes, along with the four smaller 1.8-metre Auxiliary Telescopes, used for interferometry, as well as the 2.6-metre VLT Survey Telescope. At the gate many buildings forming the observatory’s basecamp have been erected. For a view from the opposite direction, looking down from the mountaintop over the basecamp, see the earlier Picture of the Week potw1230.

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30 July 2012

Red Cocoon Harbours Young Stars

On Earth, cocoons are associated with new life. There are “cocoons” in space too, but, rather than protecting pupae as they transform into moths, they are the birthplaces of new stars.

The red cloud seen in this image, taken with the EFOSC2 instrument on ESO’s New Technology Telescope, is a perfect example of one of these star-forming regions. This is a view of a cloud called RCW 88, which is located about ten thousand light-years away and is about nine light-years across. It is not made of silk, like a moth’s cocoon, but of glowing hydrogen gas that surrounds the recently formed stars. The new stars form from clouds of this hydrogen gas as they collapse under their own gravity. Some of the more developed stars, already shining brightly, can even be seen peering through the cloud.

These hot young stars are very energetic and emit large amounts of ultraviolet radiation, which strips the electrons from the hydrogen atoms in the cloud, leaving the positively charged nuclei — protons. As the electrons are recaptured by the protons, they can emit H-alpha light, which has a characteristic red glow.

Observing the sky through an H-alpha filter is the easiest way for astronomers to find these star-forming regions. A dedicated H-alpha filter was one of the four filters used to produce this image.


23 July 2012

The Paranal basecamp from above

Looking down from a vantage point at the ESO Very Large Telescope on Cerro Paranal in the Chilean Atacama Desert, the observatory’s basecamp stretches out below. The Paranal Residencia, a haven for those working on the mountain, can be seen near the centre with the dome on its roof. To the left of the Residencia, on the other side of the road, is the basecamp’s gymnasium, and to the left of that is the Mirror Maintenance Building (MMB), where the giant VLT mirrors are periodically cleaned and recoated. Behind the MMB is the site’s power station, and further to the left is the mechanical workshop building. Winding up the mountainside in the foreground is the Star Track, a walking path from the Residencia to the summit.

The Sun had set about a quarter of an hour before this photograph was taken, leaving the basecamp bathed in beautiful orange light. This twilight creates gentle shadows which give the hills great depth. Such a sight at Paranal can only be seen during the so-called "golden hours" before sunrise or after sunset, as direct sunlight during the day results in unforgiving lighting contrasts.

This panoramic photograph was created by ESO Photo Ambassador Gerhard Hüdepohl.

Links


16 July 2012

An ALMA Antenna on the Move

This photograph shows one of the 12-metre-diameter European antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) being moved at the project’s Operations Support Facility. Since this photograph was taken, this antenna, and others like it, have been put into operation as ALMA has begun scientific observations with a partial array (see eso1137). Most recently, the Call for Proposals for ALMA’s next phase of observations closed on Thursday 12 July. Over 1100 proposals were received from astronomers around the world.

ALMA makes its observations on the Chajnantor plateau at an altitude of 5000 metres. Once construction is completed, ALMA will have an array of 66 high-precision 12-metre- and 7-metre-diameter antennas, spread over distances of up to 16 kilometres, working together as a single telescope at wavelengths of 0.32 to 3.6 millimetres. More than half of the 66 antennas are already on Chajnantor (see ann12035). Twenty-five ALMA antennas are being provided by ESO through a contract with the European AEM Consortium, 25 antennas are being provided by North America, and 16 by East Asia.

The antennas, each weighing about 100 tonnes, are assembled and tested at the Operations Support Facility, high in Chile’s Atacama region, at an altitude of 2900 metres. They are moved from there to the Chajnantor plateau, 5000 metres above sea level, with the help of two specially designed ALMA antenna transporters — huge vehicles that drive on 28 tyres, are 10 metres wide, 20 metres long and 6 metres high, weigh 130 tonnes, and have as much power as two Formula 1 engines. One of the transporters, named Otto, is being used in this photograph, which was taken when the first European antenna was handed over to the observatory in April 2011.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.


9 July 2012

The Cat's Paw Remastered

The Cat’s Paw Nebula is revisited in a combination of exposures from the MPG/ESO 2.2-metre telescope and expert amateur astronomers Robert Gendler and Ryan M. Hannahoe. The distinctive shape of the nebula is revealed in reddish puffy clouds of glowing gas against a dark sky dotted with stars.

The image was made by combining existing observations from the 2.2-metre MPG/ESO telescope of the La Silla Observatory in Chile (see ESO Photo Release eso1003) with 60 hours of exposures on a 0.4-metre telescope taken by Gendler and Hannahoe.

The resolution of the existing 2.2-metre MPG/ESO telescope observations was combined (by using their “luminance” or brightness) with the colour information from Gendler and Hannahoe’s observations to produce a beautiful combination of data from amateur and professional telescopes. For example, the additional colour information brings out the faint blue nebulosity in the central region, which is not seen in the original ESO image, while the ESO data contribute their finer detail. The result is an image that is much more than the sum of its parts.

The well-named Cat’s Paw Nebula (also known as NGC 6334) lies in the constellation of Scorpius (The Scorpion). Although it appears close to the centre of the Milky Way on the sky, it is relatively near to Earth, at a distance of about 5500 light-years. It is about 50 light-years across and is one of the most active star formation regions in our galaxy, containing massive, young brilliant blue stars, which have formed in the last few million years. It is host to possibly tens of thousands of stars in total, some of them visible and others still hidden in the clouds of gas and dust.

Links


2 July 2012

An Oasis for Astronomers — ESO’s Paranal Residencia Then and Now

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Since February 2002 (see eso0205), the Paranal Residencia has provided accommodation for people working shifts at ESO’s flagship observatory site. Paranal, in Chile’s Atacama Desert, is the home of ESO’s Very Large Telescope (VLT). This month, our Then and Now photographs — both taken by ESO Photo Ambassador Gerhard Hüdepohl — give us a unique view of how this oasis in the desert was built.

The historical photograph shows the Residencia under construction at the end of 2000. The building was designed by German architecture firm Auer+Weber, and is based around a subterranean L-shape. The building materials have the same colour as the desert, to help it blend into the landscape, and the partially completed central area of the Residencia is reminiscent of an amphitheatre, with stone tiers open to the cloudless sky.

Today, the Residencia looks quite different! Despite the subterranean location, the building’s distinctive design creates an interior with a feeling of open space. The central hall is protected by a 35-metre-wide glazed dome, which allows natural daylight into the building. The sterile amphitheatre of 2000 is reinvented as a lush tropical garden, with a pool at the bottom. Both the garden and the pool are designed to increase the humidity indoors, allowing staff some respite from the extremely arid conditions outside, in one of the driest places on Earth.

Thanks to the Residencia’s unique design, its fame has also spread beyond the astronomy community.  For example, in 2008 the James Bond movie Quantum of Solace filmed key scenes here, with the Residencia playing the role of the “Perla de las Dunas” hotel [1]. In 2009, the Residencia was selected as one of the “top 10 buildings of the decade” by the UK’s Guardian newspaper (see ann0940), and in 2012, the Paranal Observatory, including the Residencia, was featured in Land Rover’s “Perfect Places” ad campaign (see ann12008).

Notes

[1] For more information about James Bond at Cerro Paranal see eso0807, eso0838, and http://www.eso.org/public/outreach/bond/BondatParanal.html

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25 June 2012

Mars, 2099?

On a cold dark night on Mars, in the middle of an arid desert, a narrow road lit by artificial lights winds its way up to a lonely human outpost on the top of an old mountain. Or at least, that’s what a science fiction fan might make of this almost unearthly view.

The photograph actually shows ESO’s Paranal Observatory, home to the Very Large Telescope (VLT), on Earth. Nevertheless, it’s easy to imagine it as a future view of Mars, perhaps at the end of the century. Which is why Julien Girard, who took this photograph, calls it “Mars 2099”.

Located at 2600 metres altitude, ESO’s Paranal Observatory sits in one of the driest and most desolate areas on Earth, in Chile’s Atacama Desert. The landscape is so Martian, in fact, that the European Space Agency (ESA) and NASA test their Mars rovers in this region. For example, an ESA team recently tested the self-steering Seeker rover, as described in ann12048.

This image was taken at twilight, looking southwest towards the VLT, from the VISTA survey telescope on an adjacent peak. To the west lies the Pacific Ocean, only about 12 kilometres from Paranal. Rising up from the Paranal summit, the Milky Way can be seen, bearing the unmistakable mark of the southern sky — the asterism of the Southern Cross.

At Paranal, the skies can be so clear and dark on moonless nights, that the light from the Milky Way alone is enough to cast shadows. This is why ESO chose the site for the VLT, and why the observatory benefits from some of the best observing conditions in the world.

Julien Girard is an ESO astronomer based in Chile, who works at the VLT. He submitted this photograph to the Your ESO Pictures Flickr group. The Flickr group is regularly reviewed and the best photos are selected to be featured in our popular Picture of the Week series, or in our gallery. In 2012, as part of ESO’s 50th anniversary year, we are also welcoming your historical ESO-related images.

Links


18 June 2012

Yepun’s Laser and the Magellanic Clouds

One of the major enemies of astronomers is the Earth’s atmosphere, which makes celestial objects appear blurry when observed by ground-based telescopes. To counteract this, astronomers use a technique called adaptive optics, in which computer-controlled deformable mirrors are adjusted hundreds of times per second to correct for the distortion of the atmosphere.

This spectacular image shows Yepun [1], the fourth 8.2-metre Unit Telescope of ESO’s Very Large Telescope (VLT) facility, launching a powerful yellow laser beam into the sky. The beam creates a glowing spot — an artificial star — in the Earth’s atmosphere by exciting a layer of sodium atoms at an altitude of 90 km. This Laser Guide Star (LGS) is part of the VLT’s adaptive optics system. The light coming back from the artificial star is used as a reference to control the deformable mirrors and remove the effects of atmospheric distortions, producing astronomical images almost as sharp as if the telescope were in space.

Yepun’s laser is not the only thing glowing brightly in the sky. The Large and Small Magellanic Clouds can be seen, to the left and to the right of the laser beam, respectively. These nearby irregular dwarf galaxies are conspicuous objects in the southern hemisphere, and can be easily observed with the unaided eye. The prominent bright star to the left of the Large Magellanic Cloud is Canopus, the brightest star in the constellation Carina (The Keel), while the one towards the top-right of the image is Achernar, the brightest in the constellation Eridanus (The River).

This image was taken by Babak Tafreshi, an ESO Photo Ambassador.

Notes

[1] The VLT’s four Unit Telescopes are named after celestial objects in the indigenous Mapuche language, Mapudungun. The Unit Telescopes (UTs) are named: Antu (UT1, the Sun); Kueyen (UT2, the Moon); Melipal (UT3, the Southern Cross); and Yepun (UT4, Venus).

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#L


11 June 2012

Cascading Milky Way

Many astronomical photographs capture stunning vistas of the skies, and this is no exception. However, there’s something unusual about this panorama. Behind ESO’s Very Large Telescope (VLT), two streams of stars seem to cascade down like waterfalls, or perhaps rise like smoke columns to the heavens. That’s because this panorama captures the entire dome of the sky, from the zenith down to the horizon, a full 360 degrees around. The two streams are in fact a single band: the plane of our galaxy, the Milky Way, as it arcs across the sky from horizon to horizon. As it passes overhead, it appears to spread out across the whole top edge of the panorama, due to the distortion needed to squeeze the full dome of the sky into a flat, rectangular image.

To understand the picture, imagine that the far left side is attached to the far right, creating a loop around you, and that the top edge is drawn together to a single point overhead. Thus, it encompasses the full dome of the sky above you.

On the left side of the image, the silhouette of the observatory’s windsock on its pole can be seen above the building. To the left of the windsock is the bright smudge of the Small Magellanic Cloud, a neighbouring galaxy of the Milky Way. To the right, in the plane of the Milky Way, is the reddish glow of the Carina Nebula. Above that is the darkness of the Coalsack Nebula, next to the Southern Cross, and slightly higher still are the two bright stars of Alpha and Beta Centauri. The four tall buildings in the image house the 8.2-metre-diameter Unit Telescopes (UTs) of the VLT. Between the two UTs on the right is the smaller building of the VLT Survey Telescope. On the right of the image, the planet Venus glows just above the horizon.

This panorama, which shows not only the VLT on the mountaintop of Cerro Paranal, but also the beautiful sky that the observatory studies, was created by ESO Photo Ambassador Serge Brunier. Just as the VLT’s state-of-the-art technology expands our view of the Universe, Serge has used the most advanced photographic techniques to capture an entire hemisphere of the sky in one image — far more than our eyes could see in a single view.

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4 June 2012

Computing at ESO Through the Ages — The amazing advance of technology

ESO turns fifty this year, and to celebrate this important anniversary, we are showing you glimpses into our history. Once a month during 2012, a special Then and Now comparison Picture of the Week shows how things have changed over the decades at the La Silla and Paranal Observatory sites, the ESO offices in Santiago de Chile, and the Headquarters in Garching bei München, Germany.

Our pair of photographs this month show how the computing power used by ESO has changed dramatically over time. Both photographs show Austrian astronomer Rudi Albrecht in front of ESO’s computer systems, but on dates separated by decades.

In the historical image, taken in 1974 in the ESO offices in Santiago, Chile, we can see Albrecht, pencil in hand, poring over code in front of a teletype. He was working on software for the Spectrum Scanner attached to the ESO 1-metre telescope [1] located at the La Silla Observatory. The data were processed in Santiago using the Hewlett Packard 2116 minicomputer which can be seen behind the printer. This bulky computer, with one processor and a breathtaking 16 kilobytes of magnetic-core memory (!), stored the results on magnetic tape, ready for further processing by visiting astronomers on computers at their home institutes. To handle files on tape that were larger than the available memory, Albrecht developed a virtual memory system, which he contributed to the Hewlett Packard Software Center.

The present-day photograph shows Albrecht in the Data Centre at ESO Headquarters in Garching bei München, Germany, which archives and distributes data from ESO’s telescopes. He is in front of a rack containing a system with 40 processor cores, 138 terabytes of storage capacity and 83 gigabytes of RAM — over 5 million times more than the machine used by him back in 1974! Even the tablet computer he is holding far outperforms the older machine, and provides a modern alternative to pencil and paper.

Over the years, ESO’s computing systems have developed to handle the flood of scientific data from the observatory’s telescopes. Advances in telescope, detector, and computer technology mean that observatories now produce massive quantities of images, spectra, and catalogues. For instance, the two survey telescopes at Paranal, the VST and VISTA, together produce over 100 terabytes of data per year. It’s a far cry from the days of magnetic tape and 16 kilobytes of memory!

Notes

[1] The ESO 1-metre telescope was decommissioned in 1994.


28 May 2012

The Southern Milky Way Above ALMA

ESO Photo Ambassador Babak Tafreshi snapped this remarkable image of the antennas of the Atacama Large Millimeter/submillimeter Array (ALMA), set against the splendour of the Milky Way. The richness of the sky in this picture attests to the unsurpassed conditions for astronomy on the 5000-metre-high Chajnantor plateau in Chile’s Atacama region.

This view shows the constellations of Carina (The Keel) and Vela (The Sails). The dark, wispy dust clouds of the Milky Way streak from middle top left to middle bottom right. The bright orange star in the upper left is Suhail in Vela, while the similarly orange star in the upper middle is Avior, in Carina. Of the three bright blue stars that form an “L” near these stars, the left two belong to Vela, and the right one to Carina. And exactly in the centre of the image below these stars gleams the pink glow of the Carina Nebula (eso1208).

ESO, the European partner in ALMA, is providing 25 of the 66 antennas that will make up the completed telescope. The two antennas closest to the camera, on which the careful viewer can find the markings “DA-43” and “DA-41”, are examples of these European antennas. Construction of the full ALMA array will be completed in 2013, but the telescope is already making scientific observations with a partial array of antennas.

Babak Tafreshi is founder of The World At Night, a programme to create and exhibit a collection of stunning photographs and time-lapse videos of the world’s most beautiful and historic sites against a night-time backdrop of stars, planets and celestial events.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

 

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21 May 2012

Icy Penitents by Moonlight on Chajnantor

Babak Tafreshi, one of the ESO Photo Ambassadors, has captured a curious phenomenon on the Chajnantor plateau, the site of the Atacama Large Millimeter/submillimeter array (ALMA).

These bizarre ice and snow formations are known as penitentes (Spanish for “penitents”). They are illuminated by the light of the Moon, which is visible on the right on the photograph. On the left, higher in the sky, the Large and Small Magellanic Clouds can be faintly seen, while the reddish glow of the Carina Nebula appears close to the horizon on the far left.

The penitentes are natural marvels found in high-altitude regions, such as here in the Chilean Andes, typically more than about 4000 metres above sea level. They are thin spikes and blades of hardened snow or ice, which often form in clusters, with their blades pointing towards the Sun. They attain heights ranging from a few centimetres, resembling low grass, up to five metres, giving an impression of an ice forest in the middle of the desert.

The precise details of the mechanism that forms the penitentes are still not completely understood. For many years, people of the Andes believed the penitentes to be the result of strong winds prevalent in the Andes mountains. However, the strong winds have only a limited role in shaping these icy pinnacles. Nowadays, it is believed that they are the product of a combination of physical phenomena.

The process begins with sunlight shining on the surface of the snow. Due to the very dry conditions in these desert regions, the ice sublimes rather than melts — it goes from solid to gas without melting and passing through a liquid water phase. Surface depressions in the snow trap reflected light, leading to more sublimation and deeper troughs. Within these troughs, increased temperature and humidity means that melting can occur. This positive feedback accelerates the growth of the characteristic structure of the penitentes.

These icy statues are named after the spiked hats of the nazarenos, members of a brotherhood that participates in Easter processions around the world. It is not hard to picture them as an assembly of icy monks, congregating in the moonlight.

The image was taken by the side of the road that leads to ALMA. The observatory, which started Early Science operations on 30 September 2011, will eventually consist of 66 high-precision antennas operating together as a single giant telescope.

ALMA, an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ). The Joint ALMA Observatory (JAO) provides the unified leadership and management of the construction, commissioning and operation of ALMA.

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14 May 2012

Getting the VLT Ready for Even Sharper Images

This 360 degree panorama shows one of ESO’s Very Large Telescope (VLT) Unit Telescopes (UT4) whilst it was recently briefly held prisoner by ESO’s engineers. It was surrounded by a temporary cage of scaffolding as part of the preparations for the new Adaptive Optics Facility (AOF). This project will convert UT4 into a fully adaptive telescope. The AOF will correct for the blurring effects of the Earth’s atmosphere and will allow much sharper images to be achieved with the HAWK-I and MUSE instruments.

Many new components are being added to UT4 as part of the AOF. Among these is the deformable secondary mirror (DSM):  a thin-shell mirror, 1.1 metres in diameter, but just 2 millimetres thick. This mirror is thin enough to be easily deformed by more than a thousand actuators, up to a thousand times per second in order to counteract the atmosphere’s distortions. The DSM is the largest adaptive mirror manufactured to date (ann12015). Another vital element is the four Laser Guide Star Facility (4LGSF) — four special telescopes that fire laser beams high into the atmosphere to create artificial stars [1] (ann12012). Finally, the GRAAL and GALACSI adaptive optics modules will be responsible for analysing the light coming back from the laser guide stars.

This picture shows an ESO engineer supervising the work performed on UT4. To allow full access to the telescope, the cell of the primary mirror has been temporarily removed. Cables and pipes have also been removed and new ones have been installed. Mounting brackets have been added in preparation for the installation of the 4LGSF electronic cabinets and launch telescopes.

Notes

[1] The laser beams excite a layer of sodium atoms at an altitude of 90 kilometres in the atmosphere, making them glow as artificial stars.


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