Posts Tagged ‘Telescopes

The “Terrascope”

leave a comment »

On the Possibility of Using the Earth as an Atmospheric Lens


Illustration of a detector of diameter W utilizing the terrascope. Two rays of different impact parameters, but the same wavelength, lens through the atmosphere and strike the detector. The ring formed by those two rays enables a calculation of the amplification. In this setup, the detector is precisely on-axis

David Kipping
Distant starlight passing through the Earth’s atmosphere is refracted by an angle of just over one degree near the surface. This focuses light onto a focal line starting at an inner (and chromatic)boundary out to infinity – offering an opportunity for pronounced lensing. It is shown here that the focal line commences at ∼85% of the Earth-Moon separation, and thus placing an orbiting detector between here and one Hill radius could exploit this refractive lens. Analytic estimates are derived for a source directly behind the Earth (i.e. on-axis) showing that starlight is lensed into a thin circular ring of thickness W H∆/R, yielding an amplification of 8H∆/W, where H∆ is the Earth’s refractive scale height, R is its geopotential radius and W is the detector diameter. These estimates are verified through numerical ray-tracing experiments from optical to 30 µm light with standard atmospheric models. The numerical experiments are extended to include extinction from both a clear atmosphere and one with clouds. It is found that a detector at one Hill radius is least affected by extinction since lensed rays travel no deeper than 13.7 km, within the statosphere and above most clouds. Including extinction, a 1 metre Hill radius “terrascope” is calculated to produce an amplification of ∼45, 000 for a lensing timescale of ∼20 hours. In practice, the amplification is likely halved in order to avoid daylight scattering i.e. 22, 500 (∆mag=10.9) for W =1 m, or equivalent to a 150 m optical/infrared telescope.


Using Earth to See Across the Universe: The Terrascope with Dr. David Kipping:

Read also: “The Terrascope – Using Earth As A Lens

Written by physicsgg

August 2, 2019 at 8:19 pm


Tagged with ,

‘Smart dust’ technology could reshape space telescopes

leave a comment »

RIT scientist and NASA Jet Propulsion Laboratory explore adaptive optical imaging

Grover Swartzlander, associate professor at RIT’s Chester F. Carlson Center for Imaging Science, is a co-investigator on an RIT and NASA team exploring a new type of space telescope with an aperture made of swarms of particles released from a canister and controlled by a laser.

Grover Swartzlander, associate professor at RIT’s Chester F. Carlson Center for Imaging Science, is a co-investigator on an RIT and NASA team exploring a new type of space telescope with an aperture made of swarms of particles released from a canister and controlled by a laser.

Telescope lenses someday might come in aerosol cans.

Scientists at Rochester Institute of Technology and the NASA Jet Propulsion Laboratory are exploring a new type of space telescope with an aperture made of swarms of particles released from a canister and controlled by a laser.

These floating lenses would be larger, cheaper and lighter than apertures on conventional space-based imaging systems like NASA’s Hubble and James Webb space telescopes, said Grover Swartzlander, associate professor at RIT’s Chester F. Carlson Center for Imaging Science and Fellow of the Optical Society of America. Swartzlander is a co-investigator on the Jet Propulsion team led by Marco Quadrelli. Read the rest of this entry »

Written by physicsgg

December 5, 2014 at 3:29 pm


Tagged with

How to detect an exoplanet

leave a comment »

You don’t need a high-powered telescope to spot the signature of an alien world


Written by physicsgg

December 5, 2014 at 5:50 am

Hawc gamma-ray telescope captures its first image

leave a comment »

The Hawc facility is able to spot the highest-energy light ever seen on Earth - possibly the highest we will ever see

The Hawc facility is able to spot the highest-energy light ever seen on Earth – possibly the highest we will ever see

By Jason Palmer
A new set of “eyes” to capture the Universe’s highest-energy particles and light has snapped its first image.

The High-Altitude Water Cherenkov Observatory or Hawc, high on a Mexican plain, now holds the record for the highest-energy light it can capture.

The image – of the shadow cast by the Moon as it blocks the light and particles – was shown off at a meeting of the American Physical Society.

Hawc is currently made of 30 detectors, but by 2014 will comprise some 300.

Each one is a 7.3m-diameter, 4m-high tank filled with pure water.

They dot the landscape at an altitude of 4,100m in a national park near the Mexican city of Puebla.

But they do not capture the cosmic rays and gamma rays directly.

When the cosmic rays and gamma rays smash into molecules in the Earth’s atmosphere, they set off a cascade of other fast-moving particles.

It is these that the “Cherenkov” detectors actually track.

Faster than light
While the speed of light in a vacuum cannot be exceeded, the speed in matter can be much slower.

When the fast-moving particles created in the atmosphere break this speed limit inside the water of the Hawc tanks, they give off flashes of light that detectors at the tanks’ bottoms can catch.

Cherenkov telescopes such as the Hess array in Namibia or the Magic facility in the Canary Islands catch this process directly from the atmosphere when the particles first arrive at Earth.

The image shows the "shadow" of the Moon, which blocks the arrival of cosmic rays

The image shows the “shadow” of the Moon, which blocks the arrival of cosmic rays

But while Hawc catches fewer of these events high in the atmosphere, it can survey more in a given night – or day, said Hawc collaboration member Tom Weisgarber of the University of Wisconsin-Madison.

“We’re very complementary to these other instruments – but we see a very large fraction of the sky,” he told BBC News.

“Hawc doesn’t need to point in one location, and it’s unaffected by the Sun, the Moon, the weather or anything – it just depends on the atmosphere being there.”

It also claims the crown for highest-energy light we can detect – up to 100 TeV, or tens of trillions of times more energetic than the visible light we can see.

Particles and light with these blistering energies give insights into the most violent processes the cosmos hosts, from the leftovers of supernovas to supermassive black holes eating matter.

Only by catching them can we understand just how these regions create them.

But Hawc is just starting its mission, and to make sure that its first 30 detectors are working as expected, the team snapped an image exactly where it did not expect any cosmic rays – the Moon’s shadow.

A fuller array of 100 detectors should be up and running by August.

“That’s when we’ll really be able to start doing some really interesting science,” Mr Weisgarber said.


Written by physicsgg

April 15, 2013 at 12:47 pm


Tagged with

World’s smallest space telescope

leave a comment »

This shows the assembly of one of the first two satellites in the BRITE constellation at the Space Flight Laboratory of the University of Toronto Institute for Aerospace Studies. Credit: Johannes Hirn, University of Toronto

This shows the assembly of one of the first two satellites in the BRITE constellation at the Space Flight Laboratory of the University of Toronto Institute for Aerospace Studies. Credit: Johannes Hirn, University of Toronto

The smallest astronomical satellite ever built will launch shortly after 07:20 a.m. EST on Monday, 25 February 2013 as part of a mission to prove that even a very small telescope can push the boundaries of astronomy.
The satellite was designed and assembled at the Space Flight Laboratory (SFL) of the University of Toronto Institute for Aerospace Studies (UTIAS). It will be launched from the Satish Dhawan Space Centre in Sriharikota, India, along with its twin, also designed in Canada, but assembled in Austria. Each nano-satellite in the BRIght Target Explorer (BRITE) mission is a cube 20 centimetres per side, and weighing less than 7 kilograms. The BRITE satellites are part of the new wave of nano-satellites that can be designed, assembled and deployed fast and relatively cheaply. “SFL has demonstrated that nano-satellites can be developed quickly, by a small team and at a cost that is within reach of many universities, small companies and other organizations,” says Cordell Grant, Manager of Satellite Systems for the Space Flight Laboratory at UTIAS. “A nano-satellite can take anywhere from six months to a few years to develop and test, but we typically aim for two years or less.” Up to now, such nano-satellites had been used only to monitor the earth and experiment with new technologies. “Researchers, scientists and companies worldwide, who have great ideas for space-borne experiments, but do not have the means to fund a large spacecraft, can now see their ideas realized,” said Grant. “BRITE has the potential to open an entirely new market for low-cost high-performance satellites.”…

Read more at:

Written by physicsgg

February 22, 2013 at 5:36 pm


Tagged with ,

APEX takes part in sharpest observation ever

with one comment

Telescopes in Chile, Hawaii, and Arizona reach sharpness two million times finer than human vision

Artist’s impression of the quasar 3C 279

An international team of astronomers has observed the heart of a distant quasar with unprecedented sharpness, two million times finer than human vision. The observations, made by connecting the Atacama Pathfinder Experiment (APEX) telescope [1] to two others on different continents for the first time, is a crucial step towards the dramatic scientific goal of the “Event Horizon Telescope” project [2]: imaging the supermassive black holes at the centre of our own galaxy and others.

The Atacama Pathfinder Experiment (APEX)

Astronomers connected APEX, in Chile, to the Submillimeter Array (SMA) [3] in Hawaii, USA, and the Submillimeter Telescope (SMT) [4] in Arizona, USA. They were able to make the sharpest direct observation ever [5], of the centre of a distant galaxy, the bright quasar 3C 279, which contains a supermassive black hole with a mass about one billion times that of the Sun, and is so far from Earth that its light has taken more than 5 billion years to reach us. APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. APEX is operated by ESO.

The telescopes were linked using a technique known as Very Long Baseline Interferometry (VLBI). Larger telescopes can make sharper observations, and interferometry allows multiple telescopes to act like a single telescope as large as the separation — or “baseline” — between them. Using VLBI, the sharpest observations can be achieved by making the separation between telescopes as large as possible. For their quasar observations, the team used the three telescopes to create an interferometer with transcontinental baseline lengths of 9447 km from Chile to Hawaii, 7174 km from Chile to Arizona and 4627 km from Arizona to Hawaii. Connecting APEX in Chile to the network was crucial, as it contributed the longest baselines.

The observations were made in radio waves with a wavelength of 1.3 millimetres. This is the first time observations at a wavelength as short as this have been made using such long baselines. The observations achieved a sharpness, or angular resolution, of just 28 microarcseconds — about 8 billionths of a degree. This represents the ability to distinguish details an amazing two million times sharper than human vision. Observations this sharp can probe scales of less than a light-year across the quasar — a remarkable achievement for a target that is billions of light-years away.

The observations represent a new milestone towards imaging supermassive black holes and the regions around them. In future it is planned to connect even more telescopes in this way to create the so-called Event Horizon Telescope. The Event Horizon Telescope will be able to image the shadow of the supermassive black hole in the centre of our Milky Way galaxy, as well as others in nearby galaxies. The shadow — a dark region seen against a brighter background — is caused by the bending of light by the black hole, and would be the first direct observational evidence for the existence of a black hole’s event horizon, the boundary from within which not even light can escape.

The experiment marks the first time that APEX has taken part in VLBI observations, and is the culmination of three years hard work at APEX’s high altitude site on the 5000-metre plateau of Chajnantor in the Chilean Andes, where the atmospheric pressure is only about half that at sea level. To make APEX ready for VLBI, scientists from Germany and Sweden installed new digital data acquisition systems, a very precise atomic clock, and pressurised data recorders capable of recording 4 gigabits per second for many hours under challenging environmental conditions [6]. The data — 4 terabytes from each telescope — were shipped to Germany on hard drives and processed at the Max Planck Institute for Radio Astronomy in Bonn.

The successful addition of APEX is also important for another reason. It shares its location and many aspects of its technology with the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope [7]. ALMA is currently under construction and will finally consist of 54 dishes with the same 12-metre diameter as APEX, plus 12 smaller dishes with a diameter of 7 metres. The possibility of connecting ALMA to the network is currently being studied. With the vastly increased collecting area of ALMA’s dishes, the observations could achieve 10 times better sensitivity than these initial tests. This would put the shadow of the Milky Way’s supermassive black hole within reach for future observations.

Positions of the telescopes used in the 1.3 mm VLBI observations of the quasar 3C 279

[1] APEX is a collaboration between the Max Planck Institute for Radio Astronomy (MPIfR), the Onsala Space Observatory (OSO) and ESO. Operation of APEX at Chajnantor is entrusted to ESO. APEX is a pathfinder for the next-generation submillimetre telescope, the Atacama Large Millimeter/submillimeter Array (ALMA), which is being built and operated on the same plateau.

[2] The Event Horizon Telescope project is an international collaboration, coordinated by the MIT Haystack Observatory (USA).

[3] The Submillimeter Array (SMA) on Mauna Kea, Hawaii, consisting of 8 dishes of 6 m diameter each, is operated by the Smithsonian Astrophysical Observatory (USA) and the Academia Sinica Institute of Astronomy and Astrophysics (Taiwan).

[4] The Submillimeter Telescope (SMT) of 10 m diameter on top of Mount Graham, Arizona, is operated by the Arizona Radio Observatory (ARO) in Tucson, Arizona (USA).

[5] Some indirect techniques have been used to probe finer scales, for example using microlensing (see heic1116) or interstellar scintillation, but this is a record for direct observations.

[6] These systems were developed in parallel in the USA (MIT-Haystack observatory) and in Europe (MPIfR, INAF — Istituto di Radioastronomia Noto VLBI Station, and HAT-Lab). A hydrogen maser time standard (T4Science) was installed as the very precise atomic clock. The SMT and SMA had already been equipped similarly for VLBI.

[7] 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. ESO is the European partner in ALMA.

Read more:

Written by physicsgg

July 18, 2012 at 1:28 pm


Tagged with ,

At the End of the Earth, Seeking Clues to the Universe

leave a comment »

Antennas of the Atacama Large Millimeter/submillimeter Array being installed, 16,597 feet above sea level

For More Photos Press here

Trucks stall on the road to this plateau 16,597 feet up in the Atacama Desert, where scientists are installing one of the world’s largest ground-based astronomical projects. Heads ache. Noses bleed. Dizziness overcomes the researchers toiling in the shadow of the Licancabur volcano.
“Then there’s what we call ‘jelly legs,’ ” said Diego García-Appadoo, a Spanish astronomer studying galaxy formation. “You feel shattered, as if you ran a marathon.”

Still, the same conditions that make the Atacama, Earth’s driest desert, so inhospitable make it beguiling for astronomy. In northern Chile, it is far from big cities, with little light pollution. Its arid climate prevents radio signals from being absorbed by water droplets. The altitude, as high as the Himalaya base camps for climbers preparing to scale Mount Everest, places astronomers closer to the heavens.

Opened last October, the Atacama Large Millimeter/submillimeter Array, known as ALMA, will have spread 66 radio antennas near the spine of the Andes by the time it is completed next year. Drawing more than $1 billion in funding mainly from the United States, European countries and Japan, ALMA will help the oxygen-deprived scientists flocking to this region to study the origins of the universe.

The project also strengthens Chile’s position in the vanguard of astronomy. Observatories are already scattered throughout the Atacama, including the Cerro Paranal Observatory, where scientists discovered in 2010 the largest star observed to date, and the Cerro Tololo Inter-American Observatory, which was founded in 1961 and endured Chile’s tumult of revolution and counterrevolution in the 1970s.

But ALMA opens a new stage for astronomy in Chile, which is favored by international research organizations for the stability of its economy and legal system. Like other radio telescopes, ALMA does not detect optical light but radio waves, allowing researchers to study parts of the universe that are dark, like the clouds of cold gas from which stars are formed.

With ALMA, astronomers hope to see where the first galaxies were formed, and perhaps even detect solar systems with the conditions to support life, like water-bearing planets. But the scientists here express caution about their chances of finding life elsewhere in the universe, explaining that such definitive proof is likely to remain elusive.

“We won’t be able to see life, but perhaps signatures of life,” said Thijs de Graauw, a Dutch astronomer who is ALMA’s director.

Still, scientists believe ALMA will make transformational leaps possible in the understanding of the universe, enabling a hunt for so-called cold gas tracers, the ashes of exploded stars from a time about a few hundred million years after the Big Bang that astronomers call “cosmic dawn.”……
Read more:

Written by physicsgg

April 8, 2012 at 12:02 pm


Tagged with ,

Inside Euler’s Head Or how to see a telescope through the walls of its dome

with one comment

As night was falling over ESO’s La Silla Observatory in Chile on 20 December 2009, the sky was not yet dark enough for the telescopes to start observations. But conditions were perfect to perform a clever trick with the dome of the Swiss 1.2-metre Leonhard Euler Telescope: allowing us to peer inside with this photograph apparently taken through the dome.

This image is a 75-second exposure taken while the slit of the Euler telescope’s dome was performing half a rotation at full speed. Through the ghostly blur of the moving dome walls, the telescope is clearly visible. A dim light was switched on in the interior of the building especially for the purpose of this photo.

The picture was taken by Malte Tewes, a young astronomer from the École Polytechnique Fédérale de Lausanne in Switzerland, who had just finished a two-week observing run at the telescope on the evening in question. The next observer, Amaury Triaud, and the telescope’s technician, Vincent Mégevand (both pictured), were on site so they could operate the dome from the inside while Malte took the photograph from outside.

The road that leads to ESO’s nearby 3.6-metre telescope is visible lined by a chain of lights to the left of the image. In addition to the 3.6-metre telescope, the New Technology Telescope, and the MPG/ESO 2.2-metre telescope, La Silla Observatory also hosts several national and project telescopes that are not operated by ESO. The Euler telescope, named after the famous Swiss mathematician Leonhard Euler, is one of them.

Written by physicsgg

December 26, 2011 at 12:19 pm


Tagged with , ,