Largest ever Cherenkov telescope sees first light

Jul 26, 2012
View of the full H.E.S.S. array with the four 12 m telescopes and the new 28 m H.E.S.S. II telescope (Credit: H.E.S.S. Collaboration, Frikkie van Greunen)

( -- On 26 July 2012, the H.E.S.S. II telescope started operation in Namibia. Dedicated to observing the most violent and extreme phenomena of the Universe in very high energy gamma-rays, H.E.S.S. II is the largest Cherenkov telescope ever built, with its 28-meter-sized mirror. Together with the four smaller (12 meter) telescopes already in operation since 2004, the H.E.S.S. (“High Energy Stereoscopic System”) observatory will continue to define the forefront of ground-based gamma ray astronomy and will allow deeper understanding of known high-energy cosmic sources such as supermassive black holes, pulsars and supernovae, and the search for new classes of high-energy cosmic sources.

With a mass of almost 600 tons and its 28-meter - the area of two tennis courts – the new arrival is just huge. This very large telescope named H.E.S.S. II saw its first light at 0:43 a.m. on 26 July 2012, detecting its very first images of atmospheric particle cascades generated by cosmic and by cosmic rays, marking the next big step in exploring the Southern sky at gamma-ray energies. “The new telescope not only provides the largest mirror area among instruments of this type worldwide, but also resolves the cascade images at unprecedented detail, with four times more pixels per sky area compared to the smaller telescopes” states Pascal Vincent from the French team responsible for the photo sensor package at the focus of the mirror.

Gamma rays are believed to be produced by natural cosmic particle accelerators such as supermassive black holes, supernovae, pulsars, binary stars, and maybe even relics of the Big Bang. The is filled with these natural cosmic accelerators, impelling charged particles such as electrons and ions to energies far beyond what the particle accelerators built by mankind can reach. As high-energy gamma rays are secondary products of these cosmic acceleration processes, gamma ray telescopes allow us to study these sources. Today, well over one hundred cosmic sources of very high- are known. With H.E.S.S. II, processes in these objects can be investigated in superior detail, also anticipating many new sources, as well as new classes of sources. In particular, H.E.S.S. II will explore the gamma ray sky at energies in the range of tens of Giga-electronvolts – the poorly-explored transition regime between space-based instruments and current ground-based telescopes, with a huge discovery potential.

The most extreme gamma ray emitters – Active Galactic Nuclei – shine in gamma rays with an apparent energy output which is one hundred times the luminosity of the entire Milky Way, yet the radiation seems to emerge from a volume much smaller than that of our Solar System, and turns on and off in a matter of minutes, a strong signature of supermassive black holes. For some of the objects seen with the four H.E.S.S. telescopes in the last years, no counterpart at other wavelengths is known; they may represent a new type of celestial object that H.E.S.S. II will help to characterize.

When gamma rays interact high up in the atmosphere, they generate a cascade of secondary particles that can be imaged by the telescopes on the ground and recorded in their ultra-fast photo sensor 'cameras', thanks to the emission known as Cherenkov radiation – a faint flash of blue light. The high-tech camera of H.E.S.S. II is able to record this very faint flash with an “exposure time” of a few billionths of a second, almost a million times faster than a normal camera. The H.E.S.S. II camera – with an area of the size of a garage door and a weight of almost 3 tons – is “flying” 36 meters above the primary mirror in the focal plane – at the height of a 20-story building when pointing up. Despite its size, the new telescope will be able to slew twice as fast as the smaller telescopes to immediately respond to fast and transient phenomena such as gamma ray bursts anywhere in the sky.

The telescope structure and its drive system were designed by engineers in Germany and South Africa, and produced in and Germany. The 875 hexagonal mirror facets which make up the huge reflector were manufactured in Armenia, and individually characterized in Germany. The mirror alignment system results from a cooperation of German and Polish institutes. The camera, with its integrated electronics, was designed and built in France. The construction of the new H.E.S.S. II telescope was driven and financed largely by German and French institutions, with significant contributions from Austria, Poland, South Africa and Sweden.

“The successful commissioning of the new H.E.S.S. II telescope represents a big step forward for the scientists of H.E.S.S., for the astronomical community as a whole, and for Southern Africa as a prime location for this field of astronomy” - so Werner Hofmann, spokesperson of the project – “H.E.S.S. II also paves the way to the realization of CTA – the Cherenkov Array— the next generation instrument ranked top priority by astroparticle physicists and funding agencies in Europe”.

Explore further: Gas cloud in the galactic centre is part of a larger gas streamer

Provided by H.E.S.S. collaboration

5 /5 (9 votes)

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User comments : 7

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1 / 5 (1) Jul 26, 2012
the scientific excitement just keeps growing!

I do believe Russia's Spectr R radio interferometer plans on putting up telescopes for other wavelengths, infrared, x-ray, gamma-ray telescopes as well; i'm wondering if they think they can do interferometry in those wavelengths as well?!
2.1 / 5 (7) Jul 26, 2012
"the scientific excitement just keeps growing!"

It does indeed. It's a great time to live in. Only a hundred years ago conventional wisdom had the Galaxy being all the unverse.
1.2 / 5 (16) Jul 26, 2012
I don't know what to say. Just another telescope in my view.

There's not enough applied sciences coming out of astronomy in recent years or even decades.

It would be "exciting" if they discovered new fundamental physics or materials, or new energy sources. Instead, we get a Hubble Deep field equivalent just in a different spectrum. Looks nice and all, might even want to frame it if you're an astronomy buff. As for helping normal people in their daily lives? Nada.

So guy accidentally discovers Graphene using a roll of scotch tape, and another guy invents a new metallurgy process to make a steel alloy 5% stronger, both with implications and immediate and future uses in daily life...what the heck have astronomers done lately with practical benefits like these?

Its akin to a wildlife photographer who takes 10,000 photos, which most people never even see, and then most of those who do see it just go "huh, pretty picture," and there's no "material" scientific benefit manifest to anyone.
5 / 5 (2) Jul 27, 2012
Not everything is about immediate "practical" benefits. Do you have any sense of wonder or curiosity about the cosmos of which you belong to? If we only ever tried to do things that are practical, we would never advance the envelope of science and we would still think we are the center of the universe.

Here is a quote from Dr. Sagan which I believe to be relevant: "I believe our future depends powerfully on how well we understand this Cosmos in which we float like a mote of dust in the morning sky."
4.7 / 5 (7) Jul 27, 2012
The telescope structure and its drive system were designed by engineers in Germany and South Africa, and produced in Namibia and Germany.

Woha. When did Africa just enter the high-end scientific community? Awesome job, guys!

There's not enough applied sciences coming out of astronomy in recent years or even decades.

You mean looking for processes and objects that could kill us all in an instant isn't worth doing?
The universe doesn't care if you stick your head in the sand and ignore it. It will not ignore us with all the stuff it has going on.

Cosmology is as much particle physics as what the guys at CERN are doing. Out there are objects that can generate energies way beyond what we can do. Observing that we can learn about matter, energy, gravity, ...
And nay of that WILL have benefits sooner or later. Clamoring that all results be immediately applicable is a shure-fire way of stopping progress altogether within a decade.
1.8 / 5 (5) Jul 27, 2012

You mean looking for processes and objects that could kill us all in an instant isn't worth doing?

This system isn't looking for NEOs, and anything at the distance it is studying is too far away to be a concern to us anyway, in terms of catastrophism.

If we only ever tried to do things that are practical, we would never advance the envelope of science and we would still think we are the center of the universe.

If we spent the sort of money thaat goes into some of these "less useful" space projects on drought mitigation, such as a network of pumping stations across the country to move water from rivers and lakes who have average or surplus to watering stations or reservoirs in drought prone areas, the long term economic savings would pay for all the space programs you want to do.

You can build a LOT of water pipelines for crops and cattle, spanning the entire country, for the cost of the James Webb telescope. No offense, but priorities...
5 / 5 (4) Jul 27, 2012
The problem is is that that is (whoa, neat) a slippery slope to a world without any scientific advancement. Almost nothing in science is immediately applicable. You start pulling funding with the promise of diverting it to other causes and pretty soon you can't justify any science. Not to mention that even if you cut funding, there is very little guarantee that that extra money will be used for anything useful anyway.

I'm all for increasing spending on human benefiting initiatives. But not at the expense of science, our future. It would be much wiser to cut the spending on military; their budget is far greater and their good for humanity far inferior than that of science.

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