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Slitless Spectrograph
Slitless spectroscopy is astronomical spectroscopy done without a small slit to allow only light from a small region to be diffracted. It works best in sparsely populated fields, as it spreads each point source out into its spectrum, and crowded fields will be too confused to be useful. It also faces the problem that for extended sources, nearby emission lines will overlap. The Crossley telescope utilized a slitless spectrograph that was originally employed by Nicholas Mayall. The Henry Draper Catalogue, published 1924, contains stellar classifications for hundreds of thousands of stars, based on spectra taken with the objective prism method at Harvard College Observatory. The work of classification was led initially by Williamina Fleming and later by Annie Jump Cannon, with contributions from many other female astronomers including Florence Cushman. See also *Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph (JWST component) * Echelle grating An echelle ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopy
Spectroscopy is the field of study that measures and interprets the electromagnetic spectra that result from the interaction between electromagnetic radiation and matter as a function of the wavelength or frequency of the radiation. Matter waves and acoustic waves can also be considered forms of radiative energy, and recently gravitational waves have been associated with a spectral signature in the context of the Laser Interferometer Gravitational-Wave Observatory (LIGO) In simpler terms, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of astronomy, chemistry, materials science, and physics, allowing the composition, physical structure and e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Crossley Telescope
The Crossley telescope is a reflecting telescope located at Lick Observatory in the U.S. state of California. It was used between 1895 to 2010, and was donated to the observatory by Edward Crossley, its namesake. It was the largest glass reflecting telescope in the United States for several years after its recommissioning in California. Lick Director, James Edward Keeler, remarked of the Crossley in 1900, "... by far the most effective instrument in the Observatory for certain class of astronomical work." History Given to the Lick Observatory in 1895 by British politician Edward Crossley, it was rebuilt from the ground up as it was on a very flimsy mounting. It was last used in 2010 in the search for extra-solar planets but has been taken out of service due to budget cuts. The mirror, and some of the initial mounts, came from the 36-inch reflector originally mounted in Andrew Ainslie Common's backyard Ealing observatory. He had used it from 1879 to 1886 to prove the concept o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nicholas Mayall
Nicholas Ulrich Mayall (May 9, 1906 – January 5, 1993) was an American observational astronomer. After obtaining his doctorate from the University of California, Berkeley, Mayall worked at the Lick Observatory, where he remained from 1934 to 1960, except for a brief period at MIT's Radiation Laboratory during World War II. During his time at Lick, Mayall contributed to astronomical knowledge of nebulae, supernovae, spiral galaxy internal motions, the redshifts of galaxies, and the origin, age, and size of the Universe. He played a significant role in the planning and construction of Lick's reflector, which represented a major improvement over its earlier telescope. From 1960, Mayall spent 11 years as director of the Kitt Peak National Observatory until his retirement in 1971. Under his leadership KPNO, and the Cerro Tololo Inter-American Observatory, developed into two of the world's top research observatories, equipped with premier telescopes. Mayall was responsible f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harvard College Observatory
The Harvard College Observatory (HCO) is an institution managing a complex of buildings and multiple instruments used for astronomical research by the Harvard University Department of Astronomy. It is located in Cambridge, Massachusetts, United States, and was founded in 1839. With the Smithsonian Astrophysical Observatory, it forms part of the Center for Astrophysics Harvard & Smithsonian. HCO houses a collection of approximately 500,000 astronomical plates taken between the mid-1880s and 1989 (with a gap from 1953–1968). This 100-year coverage is a unique resource for studying temporal variations in the universe. The Digital Access to a Sky Century @ Harvard project is digitally scanning and archiving these photographic plates. History In 1839, the Harvard Corporation voted to appoint William Cranch Bond, a prominent Boston clockmaker, as "Astronomical Observer to the University" (at no salary). This marked the founding of the Harvard College Observatory. HCO's first tele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Williamina Fleming
(15 May 1857 – 21 May 1911) was a Scottish-American astronomer. She was a single mother, hired by the director of the Harvard College Observatory to help in the photographic classification of stellar spectra. She helped develop a common designation system for stars and cataloged more than ten thousand stars, 59 gaseous nebulae, over 310 variable stars, and 10 novae and other astronomical phenomena. Among several career achievements that advanced astronomy, Fleming is noted for her discovery of the Horsehead Nebula in 1888. Early life Williamina Paton Stevens was born in Dundee, Scotland on 15 May 1857, to Mary Walker and Robert Stevens, a carver and gilder. She worked, starting at the age of fourteen, as a pupil- teacher. In 1877, she married James Orr Fleming, an accountant and widower, also of Dundee. With links to manuscripts and other resources. The couple had one son, Edward P. Fleming. Career In 1878 she and her husband emigrated to Boston, Massachusetts, US, wh ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Annie Jump Cannon
Annie Jump Cannon (; December 11, 1863 – April 13, 1941) was an American astronomer whose cataloging work was instrumental in the development of contemporary stellar classification. With Edward C. Pickering, she is credited with the creation of the Harvard Classification Scheme, which was the first serious attempt to organize and classify stars based on their temperatures and spectral types. She developed the mnemonic "Oh! Be A Fine Girl — Kiss Me!" used by students to memorize the spectral classification of stars. She was nearly deaf throughout her career after 1893, as a result of scarlet fever. She was a suffragist and a member of the National Women's Party. Personal life Cannon was born on December 11, 1863, in Dover, Delaware. She was the eldest of three daughters born to Wilson Cannon, a Delaware shipbuilder and state senator, and his second wife, Mary Jump. Cannon's mother was the first person to teach her the constellations and she encouraged her to follow her own in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Florence Cushman
Florence Cushman (1860-1940) was an American astronomer specializing in stellar classification at the Harvard College Observatory who worked on the ''Henry Draper Catalogue''. Life Florence was born in Boston, Massachusetts in 1860 and received her early education at Charlestown High School, where she graduated in 1877. In 1888, she began work at the Harvard College Observatory as an employee of Edward Pickering. Florence was one of the "Harvard Computers" who worked under Pickering and, following his death in 1919, Annie Jump Cannon. Her classifications of stellar spectra contributed to '' Henry Draper Catalogue'' between 1918 and 1934. She stayed as an astronomer at the Observatory until 1937 and died in 1940 at the age of 80. Career at the Harvard College Observatory Florence Cushman worked at the Harvard College Observatory from 1918 to 1937. Over the course of her nearly fifty-year career, she employed the objective prism method to analyze, classify, and catalog the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fine Guidance Sensor And Near Infrared Imager And Slitless Spectrograph
Fine Guidance Sensor and Near Infrared Imager and Slitless Spectrograph (FGS-NIRISS) is an instrument on the James Webb Space Telescope (JWST) that combines a Fine Guidance Sensor and a science instrument, a near-infrared imager and a spectrograph. The FGS/NIRISS was designed by the Canadian Space Agency (CSA) and built by Honeywell as part of an international project to build a large infrared space telescope with the National Aeronautics and Space Administration (NASA) and the European Space Agency (ESA). FGS-NIRISS observes light from the wavelengths of 0.8 to 5.0 microns. The instrument has four different observing modes. Physically the FGS and NIRISS are combined, but optically they are separate with the FGS being used by the telescope to point it, whereas NIRISS is an independent science instrument. The spectroscopic mode is capable of doing exoplanet spectroscopy. The detector for NIRISS is a 2048 × 2048 pixel mercury cadmium telluride (HgCdTe) array, where each pixel is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Echelle Grating
An echelle grating (from French ''échelle'', meaning "ladder") is a type of diffraction grating characterised by a relatively low groove density, but a groove shape which is optimized for use at high incidence angles and therefore in high diffraction orders. Higher diffraction orders allow for increased dispersion (spacing) of spectral features at the detector, enabling increased differentiation of these features. Echelle gratings are, like other types of diffraction gratings, used in spectrometers and similar instruments. They are most useful in cross-dispersed high resolution spectrographs, such as HARPS, PARAS, and numerous other astronomical instruments. History The concept of a coarsely-ruled grating used at grazing angles was discovered by Albert Michelson in 1898, where he referred to it as an "echelon". However, it was not until 1923 that echelle spectrometers began to take on their characteristic form, in which the high-resolution grating is used in tandem with a cro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
