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33-592: GREGOR is the third-largest solar telescope in the world, after the Big Bear Observatory and the McMath-Pierce solar telescope . It is aimed at observing the solar photosphere and chromosphere at visible and infrared wavelengths. GREGOR sports a high-order adaptive optics (AO) system with a 256-actuator deformable mirrors and a 156-subaperture Shack-Hartmann wavefront sensor . Efforts are underway to implement multi-conjugate AO in 2014. Initial astigmatism

66-431: A computer . Recent advances have seen increasing reliance of computational algorithms in a range of miniaturised spectrometers without diffraction gratings, for example, through the use of quantum dot-based filter arrays on to a CCD chip or a series of photodetectors realised on a single nanostructure. Joseph von Fraunhofer developed the first modern spectroscope by combining a prism, diffraction slit and telescope in

99-526: A 16-inch (41 cm) Cassegrain reflecting telescope. In 1997, the primary BBSO telescope was in the 50-centimetre (20 in) class, as were the world's other high-resolution solar telescopes. However, to resolve the fundamental scale in the Sun's atmosphere (photon mean free path of 100 km (62 mi) at the Solar surface), an aperture of at least 1.5 m (59 in) is required. Correction of distortion by

132-445: A demonstrator phase for wide-field correction. It is the only MCAO system in operation with three deformable mirrors. Light corrected by adaptive optics is fed to either the visible (VIS) or near-infrared (NIRIS) spectro-polarimeter. Additionally, uncorrected light can be fed to a cryogenic spectrograph (CYRA) operating out to wavelengths of 5 microns. BBSO also operates full-disk patrol telescopes. The telescopes and instruments at

165-471: A gas cloud, and these absorption lines can also identify chemical compounds. Much of our knowledge of the chemical makeup of the universe comes from spectra. Spectroscopes are often used in astronomy and some branches of chemistry . Early spectroscopes were simply prisms with graduations marking wavelengths of light. Modern spectroscopes generally use a diffraction grating , a movable slit , and some kind of photodetector , all automated and controlled by

198-433: A low pressure sodium vapor lamp . In the original spectroscope design in the early 19th century, light entered a slit and a collimating lens transformed the light into a thin beam of parallel rays. The light then passed through a prism (in hand-held spectroscopes, usually an Amici prism ) that refracted the beam into a spectrum because different wavelengths were refracted different amounts due to dispersion . This image

231-464: A manner that increased the spectral resolution and was reproducible in other laboratories. Fraunhofer also went on to invent the first diffraction spectroscope. Gustav Robert Kirchhoff and Robert Bunsen discovered the application of spectroscopes to chemical analysis and used this approach to discover caesium and rubidium . Kirchhoff and Bunsen's analysis also enabled a chemical explanation of stellar spectra , including Fraunhofer lines . When

264-495: A material is heated to incandescence it emits light that is characteristic of the atomic makeup of the material. Particular light frequencies give rise to sharply defined bands on the scale which can be thought of as fingerprints. For example, the element sodium has a very characteristic double yellow band known as the Sodium D-lines at 588.9950 and 589.5924 nanometers, the color of which will be familiar to anyone who has seen

297-447: A multi-channel detector system or camera that detects and records the spectrum of light. The term was first used in 1876 by Dr. Henry Draper when he invented the earliest version of this device, and which he used to take several photographs of the spectrum of Vega . This earliest version of the spectrograph was cumbersome to use and difficult to manage. There are several kinds of machines referred to as spectrographs , depending on

330-452: A slit is used and a CCD-chip records the spectrum. Both gratings have a wide spacing, and one is blazed so that only the first order is visible and the other is blazed with many higher orders visible, so a very fine spectrum is presented to the CCD. In conventional spectrographs, a slit is inserted into the beam to limit the image extent in the dispersion direction. A slitless spectrograph omits

363-425: A wide range of non-optical wavelengths, from gamma rays and X-rays into the far infrared . If the instrument is designed to measure the spectrum on an absolute scale rather than a relative one, then it is typically called a spectrophotometer . The majority of spectrophotometers are used in spectral regions near the visible spectrum. A spectrometer that is calibrated for measurement of the incident optical power

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396-582: Is BBSO director. Funding comes from NASA , the National Science Foundation , the United States Air Force , and other agencies. Optical spectrometer An optical spectrometer ( spectrophotometer , spectrograph or spectroscope ) is an instrument used to measure properties of light over a specific portion of the electromagnetic spectrum , typically used in spectroscopic analysis to identify materials. The variable measured

429-446: Is about 2,055 meters (6,742 ft) above sea level , putting it above a significant portion of the atmosphere. The main observatory building is in the open waters of the lake with an approximately 200-meter (660 ft) causeway extending south from the north shore. The observatory was originally equipped with four telescopes, including two 10-inch (25 cm) refracting telescopes, a 9-inch (23 cm) reflecting coronagraph , and

462-449: Is called a spectroradiometer . In general, any particular instrument will operate over a small portion of this total range because of the different techniques used to measure different portions of the spectrum. Below optical frequencies (that is, at microwave and radio frequencies), the spectrum analyzer is a closely related electronic device. Spectrometers are used in many fields. For example, they are used in astronomy to analyze

495-535: Is most often the irradiance of the light but could also, for instance, be the polarization state. The independent variable is usually the wavelength of the light or a closely derived physical quantity, such as the corresponding wavenumber or the photon energy, in units of measurement such as centimeters, reciprocal centimeters , or electron volts , respectively. A spectrometer is used in spectroscopy for producing spectral lines and measuring their wavelengths and intensities. Spectrometers may operate over

528-503: Is operated by New Jersey Institute of Technology (NJIT). BBSO has a 1.6-meter (5.2 ft) clear-aperture Goode Solar Telescope (GST), which has no obscuration in the optical train . BBSO is located on the north side of Big Bear Lake in the San Bernardino Mountains of southwestern San Bernardino County, California , approximately 120 kilometers (75 miles) east of downtown Los Angeles . The telescopes and instruments at

561-606: Is sometimes called polychromator , as an analogy to monochromator . The star spectral classification and discovery of the main sequence , Hubble's law and the Hubble sequence were all made with spectrographs that used photographic paper. James Webb Space Telescope contains both a near-infrared spectrograph ( NIRSpec ) and a mid-infrared spectrograph ( MIRI ). An echelle -based spectrograph uses two diffraction gratings , rotated 90 degrees with respect to each other and placed close to one another. Therefore, an entrance point and not

594-528: The New Jersey Institute of Technology (NJIT) would run the BBSO. The agreement was signed in early 1997 to have NJIT lease the land and buildings from Caltech until 2048. The instruments and grants, worth about $ 1.6 million per year at that time, were transferred to NJIT on July 1, 1997. After the transfer, the directorship of BBSO passed to NJIT professor Philip R. Goode . Currently NJIT professor Wenda Cao

627-592: The 10-centimetre (3.9 in) Full Disk H-alpha (FDHA) Patrol Telescope, located in an additional small building called the Ash Dome. It is co-mounted with another small telescope dedicated to observing earthshine . The observatory also hosts a station of the Global Oscillation Network Group , an experiment in helioseismology operated by the National Solar Observatory . It is located at

660-406: The absorption spectra of gemstones, thereby allowing them to make inferences about what kind of gem they are examining. A gemologist may compare the absorption spectrum they observe with a catalogue of spectra for various gems to help narrow down the exact identity of the gem. A spectrograph is an instrument that separates light into its wavelengths and records the data. A spectrograph typically has

693-488: The camera, allowing real-time spectrographic analysis with far greater accuracy. Arrays of photosensors are also used in place of film in spectrographic systems. Such spectral analysis, or spectroscopy, has become an important scientific tool for analyzing the composition of unknown material and for studying astronomical phenomena and testing astronomical theories. In modern spectrographs in the UV, visible, and near-IR spectral ranges,

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726-581: The corrected field of view—MCAO is essential for studies requiring wide-field correction with high temporal cadence. The GST was the largest clear-aperture solar telescope in the world, able to resolve features on the Sun less than 50 km (31 mi) across, until it was replaced by the 4-meter Daniel K. Inouye Solar Telescope , which saw first light in 2019. The telescope was named the Goode Solar Telescope in July 2017. Other telescopes in BBSO include

759-576: The observatory are designed and employed specifically for studying the activities and phenomena of the Sun . Construction of the GST began in 2005 and the telescope saw first light in January 2009, with first AO-corrected imaging in the summer of 2010 in the near-infrared. Second-generation AO corrected visible light in the summer of 2012. In summer 2016, the first successful MCAO observations were made, which roughly tripled

792-403: The observatory are designed and employed specifically for studying the activities and phenomena of the Sun . The observatory location, on Big Bear Lake in the San Bernardino Mountains , was chosen for its combination of high altitude and daytime stabilizing influence of the lake, which were found to be ideal for solar observation. The location at Big Bear Lake is optimal due to the clarity of

825-424: The precise nature of the waves. The first spectrographs used photographic paper as the detector. The plant pigment phytochrome was discovered using a spectrograph that used living plants as the detector. More recent spectrographs use electronic detectors, such as CCDs which can be used for both visible and UV light. The exact choice of detector depends on the wavelengths of light to be recorded. A spectrograph

858-486: The radiation from objects and deduce their chemical composition. The spectrometer uses a prism or a grating to spread the light into a spectrum. This allows astronomers to detect many of the chemical elements by their characteristic spectral lines. These lines are named for the elements which cause them, such as the hydrogen alpha , beta, and gamma lines. A glowing object will show bright spectral lines. Dark lines are made by absorption, for example by light passing through

891-418: The shore end of the causeway and began operating in 1995. In 1995, when professor Zirin announced his intent to retire as the director, Caltech began to search for a successor. Eventually, the university decided to change the focus of what had been a solar-physics slot in the astrophysics department and to look for another organization to take over the observatory. By the spring of 1996, Caltech announced that

924-494: The sky and the presence of a body of water. The lake has more than a mile of water to the west, which is the direction from which the prevailing winds come. The cool lake provides a natural inversion that greatly reduces ground-layer turbulence and stabilizes images taken by the telescope (the water provides a cooling effect on the atmosphere surrounding the building and helps eliminate ground heat radiation waves that normally would cause optical aberrations ). The lake surface

957-452: The slit; this results in images that convolve the image information with spectral information along the direction of dispersion. If the field is not sufficiently sparse, then spectra from different sources in the image field will overlap. The trade is that slitless spectrographs can produce spectral images much more quickly than scanning a conventional spectrograph. That is useful in applications such as solar physics where time evolution

990-487: The spectrum is generally given in the form of photon number per unit wavelength (nm or μm), wavenumber (μm , cm ), frequency (THz), or energy (eV), with the units indicated by the abscissa . In the mid- to far-IR, spectra are typically expressed in units of Watts per unit wavelength (μm) or wavenumber (cm ). In many cases, the spectrum is displayed with the units left implied (such as "digital counts" per spectral channel). Gemologists frequently use spectroscopes to determine

1023-520: The terrestrial atmospheric via adaptive optics (AO) is the enabling technology for the first facility-class solar telescope built in the United States in a generation—the Goode Solar Telescope (GST). The GST is a 1.6-metre (63 in) clear-aperture off-axis telescope , which feeds its unobstructed light to visible-light and near-infrared spectro-polarimeters. The GST benefits from three generations of AO, which now includes multi-conjugate AO (MCAO) in

GREGOR Solar Telescope - Misplaced Pages Continue

1056-415: Was fixed during an upgrade with some corrective optics: two off-axis parabolic mirrors. This telescope -related article is a stub . You can help Misplaced Pages by expanding it . This article related to the Sun is a stub . You can help Misplaced Pages by expanding it . Big Bear Observatory Big Bear Solar Observatory ( BBSO ) is a university-based solar observatory in the United States. It

1089-415: Was then viewed through a tube with a scale that was transposed upon the spectral image, enabling its direct measurement. With the development of photographic film , the more accurate spectrograph was created. It was based on the same principle as the spectroscope, but it had a camera in place of the viewing tube. In recent years, the electronic circuits built around the photomultiplier tube have replaced

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