Picture of the Week

1 July 2013

European Antennas at ALMA’s Operations Support Facility

In this photograph from 2012, we see antennas destined to become part of the Atacama Large Millimeter/submillimeter Array (ALMA). The three antennas in the foreground, as well as some of those in the background, were supplied by ESO as part of its contribution to ALMA, through a contract with the European AEM Consortium [1]. In total ESO is providing 25 of the 12-metre-diameter antennas. A further twenty-five 12-metre antennas are provided by the North American ALMA partner, while the remainder, a set of twelve 7-metre and four 12-metre antennas comprising the Atacama Compact Array, are provided by the East Asian ALMA partner.

The antennas are seen here at ALMA’s Operations Support Facility (OSF), at an altitude of 2900 metres in the foothills of the Chilean Andes. Those in the foreground are in the AEM Site Erection Facility, where the antennas are assembled and rigorously tested before they are handed over to the observatory. The antennas in the background have been handed over, and are undergoing further tests or having their sensitive receivers installed. Once the antennas are ready, they are transported to the Array Operations Site, on the Chajnantor Plateau at an altitude of 5000 metres. There, they join their counterparts as part of the ALMA array, working to study some of the deepest questions of our cosmic origins. Even once all the antennas are ready, the OSF will remain the centre of activities for the daily operation of ALMA, as a workplace for astronomers and the teams responsible for maintaining the observatory.

On the horizon is the Andes mountain range, the tallest peak belonging to the conical volcano, Licancabur. Licancabur marks the border between Chile and Bolivia and dominates the landscape of the area.

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.


[1] The AEM Consortium is composed of Thales Alenia Space, European Industrial Engineering, and MT-Mechatronics.


24 June 2013

Moonlight and Zodiacal Light Over La Silla

What may look like a futuristic city out of a science fiction story, floating high above the clouds, is ESO’s longest-serving observatory, La Silla. This photograph was taken by astronomer Alan Fitzsimmons while standing near the ESO 3.6-metre telescope just after sunset. The Moon is located just outside the frame of this picture, bathing the observatory in an eerie light that is reflected off the clouds below.

The very faint band of glowing golden light just above the clouds still illuminated by the sunset is the zodiacal light. It is caused by sunlight diffused by dust particles between the Sun and the planets. This can only be seen just after sunset or just before sunrise, at particular times of year, from very good sites.

Several telescopes can be seen in this photograph. For example, the large angular structure at the end of the road is the New Technology Telescope (NTT). True to its name, when completed in 1989 the telescope included a number of revolutionary features including being the first to use full active optics as well as a revolutionary octagonal enclosure. Many of the NTT’s features went on to be incorporated into ESO’s Very Large Telescope.

The dome in the foreground, just to the right is the Swiss 1.2-metre Leonhard Euler Telescope named in honour of the famous Swiss mathematician Leonhard Euler (1707–83).

Alan 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.



17 June 2013

Thunderbolts and lightning

In this electrifying image, taken on Friday 7 June 2013, a furious thunderstorm is discharging its mighty rage over Cerro Paranal. The colossal enclosures of the four VLT Unit Telescopes, each one the size of an eight-storey building, are dwarfed under the hammering of the powerful storm.

In the left of the image, a solitary star has emerged to witness the show — a single point of light against an obscured sky. This star is Procyon, a bright binary star in the constellation of Canis Minor (The Lesser Dog).

Clouds over ESO’s Paranal Observatory are a rare sight. On average, the site experiences an astonishing 330 clear days every year. Lightning is even rarer, as the observatory is located in one of the driest places in the world: the Atacama Desert in Northern Chile, 2600 metres above sea level. If there are any clouds, most of the time the observatory stands above them.

Over a 16-year period working as an engineer on Paranal, ESO photo ambassador Gerhard Hüdepohl had seen lightning there just once before — so he grabbed his camera and ventured out into the elements to capture this unique sight.

10 June 2013

The Rise and Fall of a Supernova

An unusual new video sequence shows the rapid brightening and slower fading of a supernova explosion in the galaxy NGC 1365. The supernova, which has been named SN 2012fr, was discovered by French astronomer Alain Klotz on the 27 October 2012. The images captured by the small TAROT robotic telescope, located at ESO’s La Silla Observatory in Chile, have been compiled to create this unique movie.

Supernovae are the results of the explosive and cataclysmic deaths of certain types of stars. They are so brilliant that they can outshine their entire parent galaxy for many weeks before slowly fading from sight.

The supernova 2012fr [1] was discovered by Alain Klotz on the afternoon of 27 October 2012. He was busy measuring the brightness of a faint variable star in an image from the TAROT (Télescope à Action Rapide pour les Objets Transitoires) robotic telescope at ESO’s La Silla Observatory, when he noticed a new object that was not present in an image taken three days earlier. After checking with telescopes and astronomers all across the world the bright object was confirmed to be a Type Ia supernova.

Some stars co-habit with a second star, both orbiting around a common centre of gravity. In some cases one of them might be a very old white dwarf that is stealing material from its companion. At some point the white dwarf has siphoned off so much matter from its companion that it becomes unstable and explodes. This is known as a Type Ia supernova.

This kind of supernova has become very important as they are the most reliable way of measuring distances to very remote galaxies in the early Universe. Beyond the local group of galaxies, astronomers needed to find very bright objects with predictable properties that could act as signposts to help them map out the expansion history of the Universe. Type Ia supernovae are ideal as their brightnesses peak and fade in almost the same way for each explosion. Measurements of the distances to Type Ia supernovae led to the discovery of the accelerating expansion of the Universe, work that was awarded the Nobel Prize for Physics in 2011.

The host galaxy of this supernova is NGC 1365 (see also potw1037a), an elegant barred spiral galaxy, located 60 million light-years away towards the constellation of Fornax (The Furnace). With its diameter of about 200 000 light-years, it stands out among the other galaxies in the Fornax cluster. A colossal straight bar runs through the galaxy, containing the nucleus at the centre. The new supernova can be easily spotted just above the core, in the middle of the image.

Astronomers discovered more than 200 new supernovae in 2012, of which SN 2012fr is among the brightest. The supernova was first spotted when it was very faint on the 27 October 2012, and it reached its peak brightness on 11 November 2012 [2]. It was then easily seen as a faint star through a medium-sized amateur telescope. The video was compiled from a series of images taken of the galaxy over a period of three months, from the discovery in October until mid-January 2013.

TAROT is a 25-centimetre optical robotic telescope, able to move very fast, and to start an observation within a second. It was installed at La Silla Observatory in 2006 with the purpose of detecting cosmic gamma-ray bursts. The images that revealed SN 2012fr were captured using blue, green and red filters.


[1] Supernovae are designated by the year in which they are discovered, and the order in which they are discovered during that year, by using letters of the alphabet. The fact that the the supernova was discovered by a French team and it has been designated by the letters “fr” is pure coincidence.

[2] At this time it was magnitude 11.9. This is about 200 times too faint to see with the unaided eye even on a clear and dark night. But if the supernova at its peak brightness and our star the Sun were seen together at the same distance from the observer the supernova would appear about 3000 million times brighter than the Sun.



Alain Klotz
Institut de Recherche en Astrophysique et Planetologie
Toulouse, France
Tel: +33 05 61 55 66 66
Email: alain.klotz@irap.omp.eu

Richard Hook
ESO, La Silla, Paranal, E-ELT & Survey Telescopes Press Officer
Garching bei München, Germany
Tel: +49 89 3200 6655
Cell: +49 151 1537 3591
Email: rhook@eso.org

3 June 2013

Three Planets Dance Over La Silla

It’s a real treat for photographers and astronomers alike: our skies are currently witnessing a phenomenon known as a syzygy — when three celestial bodies (or more) nearly align themselves in the sky. When celestial bodies have similar ecliptic longitude, this event is also known as a triple near-conjunction. Of course, this is just a trick of perspective, but this doesn't make it any less spectacular. In this case, these bodies are three planets, and the only thing needed to enjoy the show is a clear view of the sky at sunset.

Luckily, this is what happened for ESO photo ambassador Yuri Beletsky, who had the chance to spot this spectacular view from ESO's La Silla Observatory in northern Chile on Sunday 26 May. Above the round domes of the telescopes, three of the planets in our Solar System — Jupiter (top), Venus (lower left), and Mercury (lower right) — were revealed after sunset, engaged in their cosmic dance.

An alignment like this happens only once every few years. The last one took place in May 2011, and the next one will not be until October 2015. This celestial triangle was at its best over the last week of May, but you may still be able to catch a glimpse of the three planets as they form ever-changing arrangements during their journey across the sky.


27 May 2013

Ripples Across the Chilean Sky

At first sight, this mesmerising image might look like the waves caused by a stone thrown into a lake. And yet, this is the result of the apparent motion of the stars through the southern sky and some magic performed by the photographer. The image was taken at Cerro Armazones, a mountain peak 3060 metres above sea level, which lies in the central part of the Atacama Desert, in the Chilean Andes.

The long bright stripes are star trails and each one marks the path of a single star across the dark night sky. By leaving the camera’s shutter open for a long period of time, the movement of the stars, imperceptible to the naked eye, is revealed. Exposure times of as little as 15 minutes are long enough to do the trick. In this case, the photographer combined many shorter exposures to form the final image. The very wide-angle lens used for this series shows the celestial pole to the right, and the equator just above the short tower.

The amazingly large number of star trails in this picture also reveals the incredible quality of the night sky at Armazones: the atmosphere is extremely clear and there is no light pollution thanks to the mountaintop’s remote location. This is one of the reasons why this mountain was chosen to be the future home of the world’s biggest eye on the sky: the upcoming European Extremely Large Telescope (E-ELT).

20 May 2013

Admiring the Galaxy

It is difficult for even the most seasoned astronomer to resist taking time out of a busy observing schedule to stop and stare up at the gloriously rich southern sky. This image is a self portrait taken by astronomer Alan Fitzsimmons, who took this photo between observing sessions at ESO’s La Silla Observatory.

This bold photo shows the contrast between a simple, still and dark figure on Earth and the brilliant and bright starry night sky. In this picture, the sky is dominated by the enormous splash of stars and dust which make up the centre of the Milky Way, our home galaxy.

ESO’s observatories are located in the Atacama Desert in northern Chile, a region with very few inhabitants, which combines very dark nights with extremely clear atmospheric conditions, both factors conducive to making high quality observations.

La Silla is ESO’s first observatory. Inaugurated in 1969, it is home to a number of telescopes with mirror diameters of up to 3.6 metres. With more than 300 clear nights every year, La Silla is in an ideal position to house advanced observing instruments, but it also makes it a fabulous place to just stop and gaze up into the sky.

Alan 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 Picture of the Week series or in our picture gallery.

13 May 2013

Milky Way Shines over Snowy La Silla

In the outskirts of the Atacama Desert, far from the light-polluted cities of northern Chile, the skies are pitch-black after sunset. Such dark skies allow some of the best astronomical observing to take place — and at an altitude of 2400 metres, ESO’s La Silla Observatory has an incredibly clear view of the night sky. However, even such a remote, high, and dry location cannot always escape the weather that sometimes comes with the winter months, when blankets of snow can cover the mountain peak and its telescope domes.

This image shows a wintry La Silla sitting beneath a spray of stars from our Milky Way, the plane of which slants across the frame. Visible (from right to left) are the ESO 3.6-metre telescope, the 3.58-metre New Technology Telescope (NTT), the ESO 1-metre Schmidt telescope, and the MPG/ESO 2.2-metre telescope, which has snow on its dome. The small dome of the decommissioned Coudé Auxiliary Telescope can be seen adjacent to that of the ESO 3.6-metre telescope, and between it and the NTT are the water tanks of the observatory.

While the sight of snow at La Silla may initially be surprising, the high altitude ESO sites can experience both hot and cold temperatures through the year, and occasionally be subject to harsh conditions.

This photograph was taken by José Francisco Salgado, an ESO Photo Ambassador.

6 May 2013

Lore on the Move

In this photograph one of the two ALMA transporters, Lore, is carrying one of the 7-metre-diameter antennas of ALMA, the Atacama Large Millimeter/submillimeter Array. Lore and her twin, Otto, are two bright yellow 28-wheeled vehicles, custom-built to move ALMA’s antennas around on the Chajnantor Plateau at an elevation of 5000 metres. By doing this, they can reconfigure the telescope array to make the most useful observations of a given target. They also move antennas between Chajnantor and the lower altitude Operations Support Facility for maintenance.

ALMA has a main array of fifty 12-metre-diameter antennas, and an additional array of twelve 7-metre antennas and four 12-metre antennas, known as the Atacama Compact Array (ACA). Lore is carrying one of the smaller, 7-metre antennas of the ACA. The 12-metre antennas of the main array cannot be placed closer than 15 metres apart as they would otherwise bump into each other. This minimum separation between antennas limits the maximum scale of the features that they can detect in the sky. This means that the main array cannot observe the broadest features of extended objects such as giant clouds of molecular gas in the Milky Way, or nearby galaxies. The ACA is specifically designed to help ALMA make better observations of these extended objects. Its smaller 7-metre antennas can be placed closer together, making them better able to measure the broader structures that the main array misses.

The dramatic icy spikes in the foreground are known as penitentes (Spanish for penitents). These are a curious natural phenomenon found in high altitude regions, typically more than 4000 metres above sea level. They are thin blades of hardened snow or ice which point towards the Sun, attaining heights from a few centimetres up to several metres.

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.


29 April 2013

Wings for Science Fly Over ALMA

This beautiful image, taken in December 2012, shows the array of antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) [1], the largest astronomy project in existence, located at the Chajnantor Plateau in the Chilean Andes. The large antennas are 12 metres in diameter, and the smaller ones, gathered together in the middle of the image, form the ALMA Compact Array (ACA), which is made up of 12 antennas with a diameter of 7 metres. When the array is completed, there will be a total of 66 antennas.

ESO has initiated an outreach partnership with the ORA Wings for Science project, a non-profit organisation which offers aerial support to public research while on a year-long journey around the world. The two crew members of the Wings for Science Project, Clémentine Bacri and Adrien Normier, fly a special environmentally friendly ultralight [2] to help out scientists by providing aerial capabilities ranging from air sampling to archaeology, biodiversity observation and 3D terrain modelling.

The short movies and amazing pictures that are produced during the flights are used for educational purposes and for promoting local research. Their circumnavigation started in June 2012 and will finish in June 2013 with a landing at the Paris Air Show.


[1] The Atacama Large Millimeter/submillimeter Array (ALMA), an international astronomy facility, is a partnership of Europe, North America and East Asia in cooperation with the Republic of Chile. ALMA is funded in Europe by the European Southern Observatory (ESO), in North America by the U.S. National Science Foundation (NSF) in cooperation with the National Research Council of Canada (NRC) and the National Science Council of Taiwan (NSC) and in East Asia by the National Institutes of Natural Sciences (NINS) of Japan in cooperation with the Academia Sinica (AS) in Taiwan. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), which is managed by Associated Universities, Inc. (AUI) 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.

[2] The ultralight aircraft is a NASA-award winning Pipistrel Virus SW 80 using only 7 litres of fuel per 100 kilometres — less than most cars.


22 April 2013

Silver and Blue at Paranal

What might count as a beautifully clear day anywhere else in the world is actually an unusually cloudy day at ESO’s Paranal Observatory in the Atacama Desert. As this is one of the driest places on the planet, it is very uncommon to see clouds in the sky. Many astronomers and engineers who spend time at the site find the cloudless sky one of the most striking things about working in the Atacama Desert. This gorgeous 360-degree panorama photo, taken by ESO contractor Dirk Essl in 15 separate exposures, has captured one of the rare days with clouds at Paranal. A few thin, wispy cirrus clouds can be seen above the enclosures of the Very Large Telescope. These clouds form at high altitudes and are made up of tiny ice crystals.

Paranal Observatory receives less than 10 millimetres of rainfall per year, which is just one of the reasons why this 2600-metre-high mountain was chosen as the site for ESO’s Very Large Telescope (VLT). This panorama includes the four large Unit Telescopes of the VLT as well as the four smaller Auxiliary Telescopes in their rounded enclosures, one in the foreground and the other three further away. The tracks on the ground are there so that the the Auxiliary Telescopes can be moved into different positions.

Dirk 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.


15 April 2013

Under the Spell of the Magellanic Clouds

This beautiful image of the Atacama Large Millimeter/submillimeter Array (ALMA), showing the telescope’s antennas under a breathtaking starry night sky, comes from Christoph Malin, an ESO Photo Ambassador. This is a still frame taken from one of his painstakingly created time-lapse videos of ALMA, which are also available (see ann12099).

Located on the Chajnantor Plateau at an elevation of 5000 metres, 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.

Glowing brightly in the sky, the Large and Small Magellanic Clouds stand out above the antennas. These nearby irregular dwarf galaxies are conspicuous objects in the southern hemisphere, even with the naked eye. These galaxies are both orbiting the Milky Way — our galaxy — and there is evidence that both have been greatly distorted by their interaction with the Milky Way as they travel close to it.
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.


8 April 2013

A Sparkling Ribbon of Stars — The Southern Milky Way over La Silla

This panoramic photograph, taken by Alexandre Santerne, shows an insider’s view of the disc of the Milky Way, our home galaxy, as well as a cold winter’s night, with a sprinkling of snow at ESO’s La Silla Observatory in Chile. From our vantage point within it, the disc of the Milky Way appears as a sparkling ribbon of stars stretching across the sky. In this panorama, the Milky Way is distorted into an arc by the wide-angle projection.

Peeking over the hill on the left of this photo is the ESO 3.6-metre telescope, home to the world's foremost exoplanet hunter, HARPS (the High Accuracy Radial velocity Planet Searcher). On the far right is the Swiss 1.2-metre Leonhard Euler Telescope, built and operated by the Geneva Observatory.

There are a number of reasons why La Silla is such an ideal location for observing the night sky in general, and the Milky Way in particular. Firstly, it’s located in the southern hemisphere, giving us a better view of the richer central region of the galaxy, and secondly, it’s located far from light and urban pollution, at an altitude of 2400 metres above sea level, making the nights dark and the atmosphere clear.

Alexandre 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. Since submitting the photo, Alexandre has also become an ESO Photo Ambassador.


1 April 2013

Stars Circle over the Residencia at Cerro Paranal

This image from ESO Photo Ambassador Farid Char, of the southern night sky over the Residencia “hotel” at ESO’s Paranal Observatory in Chile, presents a beautifully star-filled and dynamic view of the heavens.

To make the swirling star trails on this image, Farid used a 30-minute exposure to reveal the observed movement of the stars due to the rotation of the Earth. In the centre is the apparently still point of the south celestial pole. On the left, and at the top of the image, are the extended blurs of the Large and Small Magellanic Clouds, neighbouring galaxies of the Milky Way.

The dark glass dome below the circling stars is part of the roof of the Residencia building. This unique partially subterranean construction has been in use since 2002 by scientists and engineers working at the observatory. During the day, the 35-metre-wide dome allows natural daylight into the building.

At the observatory, located on a mountain at an elevation of 2600 metres in the arid Atacama Desert, the excellent astronomical conditions come at a price. People there face intense sunlight during the day, very low humidity, and the high altitude can leave them short of breath. To help them relax and rehydrate after long shifts on the mountaintop, there is an artificial oasis at the Residencia, with a small garden, a swimming pool that humidifies the air, a lounge, a dining room, and other recreational facilities. The building can accommodate over 100 people.


25 March 2013

The Lost Galaxy

This image depicts the galaxy NGC 4535, in the constellation of Virgo (The Maiden), on a beautiful background full of many distant faint galaxies. Its almost circular appearance shows that we observe it nearly face-on. In the centre of the galaxy, there is a well-defined bar structure, with dust lanes that curve sharply before the spiral arms break from the ends of the bar. The bluish colour of the spiral arms points to the presence of a large number of hot young stars. In the centre, however, older and cooler stars give the bulge of the galaxy a yellower appearance.

This visible image was made with the FORS1 instrument on ESO’s 8.2-metre Very Large Telescope. The galaxy can also be seen through smaller amateur telescopes, and was first observed by William Herschel in 1785. When seen through a smaller telescope, NGC 4535 has a hazy, ghostly appearance, which inspired the prominent amateur astronomer Leland S. Copeland to name it “The Lost Galaxy” in the 1950s.

NGC 4535 is one of the largest galaxies in the Virgo Cluster, a massive cluster of as many as 2000 galaxies, about 50 million light-years away. Although the Virgo Cluster is not much larger in diameter than the Local Group — the galaxy cluster to which the Milky Way belongs —  it contains almost fifty times as many galaxies.

11 March 2013

Comets and Shooting Stars Dance Over Paranal

This impressive picture was taken on 5 March 2013 by Gabriel Brammer, one of the ESO Photo Ambassadors, and shows a sunset view of the Paranal Observatory, featuring two comets that are currently moving across the southern skies. Close to the horizon, on the right-hand side of the image, Comet C/2011 L4 (Pan-STARRS), the brightest of the two, shows a bright tail that is caused mainly by dust reflecting the sunlight. In the centre of the image, just above the right-hand slopes of Cerro Paranal, the greenish coma — a nebulous envelope around the nucleus — of Comet C/2012 F6 (Lemmon) can be distinguished, followed by a fainter tail. The green colour is a result of the ionisation of gases in the coma by sunlight. You might even be tricked into thinking that there is a third comet visible in this photo, but the bright object whizzing between comets Lemmon and Pan-STARRS is a serendipitous shooting star burning up in the atmosphere at just the right time and in the right place.

4 March 2013

Snow Comes to the Atacama Desert

The Atacama Desert is one of the driest places in the world. Several factors contribute to its arid conditions. The magnificent Andes mountain range and the Chilean Coast Range block the clouds from the east and west, respectively. In addition, the cold offshore Humboldt Current in the Pacific Ocean, which creates a coastal inversion layer of cool air, hinders the formation of rain clouds. Moreover, a region of high pressure in the south-eastern Pacific Ocean creates circulating winds, forming an anticyclone, which also helps to keep the climate of the Atacama Desert dry. These arid conditions were a major factor for ESO in placing the Very Large Telescope (VLT) at Paranal, in the Atacama Desert. At the Paranal Observatory, located on the summit of Cerro Paranal, the precipitation levels are usually below ten millimetres per year, with the humidity often dropping below 10%. The observational conditions are excellent, with over 300 clear nights per year.

The splendid conditions for astronomical observations in the Atacama Desert are only rarely disturbed by the weather. However, for perhaps a couple of days each year, snow pays a visit to the Atacama Desert. This picture shows a beautiful panoramic view of Cerro Paranal. The VLT is on the peak on the left, and the VISTA survey telescope is on a slightly lower peak, a short distance to the right. The blue sky shows that this is yet another clear sunny day. This time, though, something is different: a thin dusting of snow has transformed the desert landscape, producing an unusual view of rare beauty.

This image was taken by ESO Photo Ambassador Stéphane Guisard on 1 August 2011.


25 February 2013

The Comet and the Laser

Gerhard Hüdepohl, one of the ESO Photo Ambassadors, captured this spectacular image of ESO’s Very Large Telescope (VLT) during the testing of a new laser for the VLT 14 February 2013. It will be used as a vital part of the Laser Guide Star Facility (LGSF), which allows astronomers to correct for most of the disturbances caused by the constant movement of the atmosphere in order to create much sharper images. Nevertheless, is hard not to think of it as a futuristic laser cannon being pointed towards some kind of distant space invader.

As well as the amazing view of the Milky Way seen over the telescope, there is another feature making this picture even more special. To the right of the centre of the image, just below the Small Magellanic Cloud and almost hidden among the myriad stars seen in the dark Chilean sky, there is a green dot with a faint tail stretching to its left. This is the recently discovered and brighter-than-expected Comet Lemmon, which is currently moving slowly through the southern skies.

18 February 2013

Super-thin Mirror Under Test at ESO

This remarkable deformable thin-shell mirror has been delivered to ESO at Garching, Germany and is shown undergoing tests. It is 1120 millimetres across but just 2 millimetres thick, making it much thinner than most glass windows. The mirror is very thin so that it is flexible enough for magnetic forces applied to it to alter the shape of its reflective surface. When in use, the mirror's surface will be constantly changed by tiny amounts to correct for the blurring effects of the Earth’s atmosphere and so create much sharper images.

The new deformable secondary mirror (DSM) will replace the current secondary in one of the VLT’s four Unit Telescopes. The entire secondary structure includes a set of 1170 actuators that apply a force on 1170 magnets glued to the back face of the thin shell. Sophisticated special-purpose electronics control the behaviour of the thin shell mirror. The reflecting surface can be deformed up to a thousand times per second by the action of the actuators.

The complete DSM system was delivered to ESO by the Italian companies Microgate and ADS in December 2012 and concludes eight years of sustained development efforts and manufacturing. This is the largest deformable mirror ever produced for astronomical purposes and is the latest of a long line of such mirrors. The extensive experience of these contractors shows in the high performance of the system and its reliability. The installation on the VLT is scheduled to start in 2015.

The shell mirror (ann12015) itself was manufactured by the French company REOSC. It is a sheet of ceramic material that has been polished to a very accurate shape. The manufacturing process starts with a block of Zerodur ceramic, provided by Schott Glass (Germany) that is more than 70 millimetres thick. Most of this material is ground away to create the final thin shell that must be carefully supported at all times as it is extremely fragile.


11 February 2013

Laser and Light Painting

On a clear night in Bavaria, ESO staff attended the filming of an ESOcast episode focusing on ESO’s new compact laser guide star unit, seen here in action at the Allgäu Public Observatory in Ottobeuren, Germany. Using the glow from their mobile phones, staff took advantage of the long-exposure photograph to draw the letters “ESO” in light, while standing in front of the observatory. Just left of the vertical laser beam, the Milky Way can be seen. Just above the horizon over the observatory, the dotted tracks of aircraft can be seen in the distance. The laser has a powerful beam of 20 watts, and to protect pilots and passengers a no-fly zone around the observatory was created by the Deutsche Flugsicherung (responsible for air traffic control in Germany) during the nighttime observing hours.

Laser guide stars are artificial stars created in the Earth’s atmosphere using a laser beam. The laser makes the sodium atoms in a layer 90 kilometres up in the atmosphere glow and so creates an artificial star in the sky that can be observed by a telescope. Using measurements of the artificial star, adaptive optics instruments can then correct the blurring effect of the atmosphere in the observations.

ESO’s innovative concept uses a powerful laser whose beam is launched with a small telescope, combined into a single modular unit which can be mounted directly on a large telescope. The concept, which has been patented and licensed by ESO, will be used to provide the Very Large Telescope (VLT) with four similar laser units. It will also play a key role in the units that will equip the future European Extremely Large Telescope (E-ELT).

At the time of filming, the unit was undergoing testing before being shipped to the ESO Paranal Observatory in Chile, home of the VLT.


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