Across the electromagnetic spectrum, different materials and techniques are used to focus and detect light at a variety of wavelengths. The goal for telescopes in every waveband is to collect as much light as possible and focus a sharp detailed image on a detector. Telescopes have similar limitations, so telescopes have to be redesigned to focus and detect light across the electromagnetic spectrum. The range of wavelengths the human eye can focus and detect defines the optical waveband. Telescope Design from Infrared to Gamma Ray Communication systems were developed to share the images and data from land- and space-based telescopes allowing astrophysicists to compare images and spectra of objects and phenomena in as many wavebands as possible to get a more complete picture of the Universe. As rocket and satellite technology improved, space observatories were built that carried an array of tools capable of capturing images and spectra at a variety of wavelengths. In the second half of the 20th century, methods to focus and detect light at a variety wavebands were developed that enabled space telescopes to provide images of the invisible radiation from astronomical objects. The international collaboration includes: Cork Institute of Technology, National University of Ireland in Galway, and University College Dublin in Ireland McGill University in Canada and DESY in Germany.Multiwavelength Land & Space Observatories: The atmospheric effects on incoming light in each waveband determines the placement of telescopes. In the United States, those are the Barnard College/Columbia University, University of California Los Angeles, University of California Santa Cruz, University of Chicago, the University of Delaware, Georgia Institute of Technology, University of Iowa, Iowa State University, University of Minnesota, Purdue University, University of Utah, and Washington University in St. VERITAS is a collaboration between CfA and a number of other research institutions. That in turn reveals the energy and origin of the primary gamma ray photons. The telescopes are about 100 meters (328 feet) apart in a rectangular arrangement, allowing the instruments to reconstruct the shape and direction of the shower of photons. The telescopes measure the Cherenkov light using photomultiplier tubes, which make a detectable electrical signal out of a small number of photons that are too faint for ordinary telescope cameras. The first VERITAS telescope began operation in 2004, with the full four-instrument array beginning observations in 2007. This location provides clear, dark skies through much of the year. The VERITAS observatory consists of four 12-meter (39-foot) optical telescopes located on Mt. The shower of Cherenkov photons covers an area roughly 260 meters (850 feet) in diameter. Gamma ray observatories like VERITAS effectively use the whole atmosphere as their detector, and track the blue visible light produced from the air shower using optical telescopes. Those particles in turn produce a burst of blue light known as Cherenkov radiation. When the highest-energy photons enter the atmosphere, they produce a burst of particles known as an “air shower”. VERITAS and similar ground-based gamma ray observatories take another route. However, the most energetic gamma rays come from sources that are too faint for the relatively small detectors in space telescopes. Gamma ray researchers look at galaxies for the sources of cosmic ray particles and signs of dark matter collisions.Įarth’s atmosphere blocks most of these photons, which means many gamma ray experiments are space-based, such as NASA’s Fermi Gamma Ray Observatory. Problems with conventional telescope designs Conventional telescope designs require reflection or refraction in a manner that does not work well for X-rays. Gamma rays are the highest energy form of light, produced by interactions between particles in extreme environments: matter swirling around the supermassive black holes known as blazars, supernova remnants, material battered by neutron stars, and many more. A Wolter telescope is a telescope for X-rays that only uses grazing incidence optics mirrors that reflect X-rays at very shallow angles. An optical telescope uses a large, curved-glass primary mirror to gather light, but X-rays would penetrate such a mirror’s reflective coating an X-ray telescope’s mirrors must be. Credit: CfA/Rick Peterson The Telescopes and the Science
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