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82-622: It was founded in 1833 by Thomas Grubb as the Grubb Telescope Company , located in Dublin . Control of the company passed to his son Howard Grubb in the 1860s. They produced dozens of telescopes, including some of the largest of the 19th century, such as the 48-inch (1.2 m) Great Melbourne Telescope (a reflecting telescope ) in 1868, a 27-inch (0.69 m) refractor for the Vienna Observatory in 1878, and

164-500: A continuous spectrum , hot gases emit light at specific wavelengths, and hot solid objects surrounded by cooler gases show a near-continuous spectrum with dark lines corresponding to the emission lines of the gases. By comparing the absorption lines of the Sun with emission spectra of known gases, the chemical composition of stars can be determined. The major Fraunhofer lines , and the elements with which they are associated, appear in

246-445: A wave pattern created by an interferometer . This wave pattern sets up a reflection pattern similar to the blazed gratings but utilizing Bragg diffraction , a process where the angle of reflection is dependent on the arrangement of the atoms in the gelatin. The holographic gratings can have up to 6000 lines/mm and can be up to twice as efficient in collecting light as blazed gratings. Because they are sealed between two sheets of glass,

328-531: A cluster were moving much faster than seemed to be possible from the mass of the cluster inferred from the visible light. Zwicky hypothesized that there must be a great deal of non-luminous matter in the galaxy clusters, which became known as dark matter . Since his discovery, astronomers have determined that a large portion of galaxies (and most of the universe) is made up of dark matter. In 2003, however, four galaxies (NGC 821, NGC 3379 , NGC 4494, and NGC 4697 ) were found to have little to no dark matter influencing

410-476: A glassmaker to create very pure prisms, which allowed him to observe 574 dark lines in a seemingly continuous spectrum. Soon after this, he combined telescope and prism to observe the spectrum of Venus , the Moon , Mars , and various stars such as Betelgeuse ; his company continued to manufacture and sell high-quality refracting telescopes based on his original designs until its closure in 1884. The resolution of

492-458: A laboratory because they are forbidden lines ; the low density of a nebula (one atom per cubic centimetre) allows for metastable ions to decay via forbidden line emission rather than collisions with other atoms. Not all emission nebulae are found around or near stars where solar heating causes ionisation. The majority of gaseous emission nebulae are formed of neutral hydrogen. In the ground state neutral hydrogen has two possible spin states :

574-405: A material that emits electromagnetic radiation at all wavelengths. In 1894 Wilhelm Wien derived an expression relating the temperature (T) of a black body to its peak emission wavelength (λ max ): b is a constant of proportionality called Wien's displacement constant , equal to 2.897 771 955 ... × 10  m⋅K . This equation is called Wien's Law . By measuring the peak wavelength of

656-543: A metal billiard-table manufacturer. He diversified into making telescopes and erected a public observatory near his factory at 1 Upper Charlemont Street, Portobello, Dublin . As makers of some of the largest and best-known telescopes of the Victorian era, the company was at the forefront of optical and mechanical engineering. His innovations for large telescopes included clock-driven polar mounts , whiffletree mirror mounting cells and Cassegrain reflector optics. Later,

738-555: A metric 1.93-metre (76 in) mirror), Okayama Observatory (Japan, 1960) and Helwan Observatory (Egypt, 1963). They continued to produce numerous smaller telescopes in this period, including a 36-inch (0.91 m) for Cambridge Observatory (UK, 1955), a 40-inch (1.0 m) for the South African Astronomical Observatory (1963), and a 48-inch (1.2 m) for Dominion Astrophysical Observatory (Victoria, Canada, 1961). The next major project

820-534: A prism is limited by its size; a larger prism will provide a more detailed spectrum, but the increase in mass makes it unsuitable for highly detailed work. This issue was resolved in the early 1900s with the development of high-quality reflection gratings by J.S. Plaskett at the Dominion Observatory in Ottawa, Canada. Light striking a mirror will reflect at the same angle, however a small portion of

902-414: A spectrum can be calibrated by observing the spectrum of emission lines of known wavelength from a gas-discharge lamp . The flux scale of a spectrum can be calibrated as a function of wavelength by comparison with an observation of a standard star with corrections for atmospheric absorption of light; this is known as spectrophotometry . Radio astronomy was founded with the work of Karl Jansky in

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984-483: A star, the surface temperature can be determined. For example, if the peak wavelength of a star is 502 nm the corresponding temperature will be 5772 kelvins . The luminosity of a star is a measure of the electromagnetic energy output in a given amount of time. Luminosity (L) can be related to the temperature (T) of a star by: where R is the radius of the star and σ is the Stefan–Boltzmann constant, with

1066-486: A telescope. Some binary stars, however, are too close together to be resolved . These two stars, when viewed through a spectrometer, will show a composite spectrum: the spectrum of each star will be added together. This composite spectrum becomes easier to detect when the stars are of similar luminosity and of different spectral class . Spectroscopic binaries can be also detected due to their radial velocity ; as they orbit around each other one star may be moving towards

1148-405: A value of 5.670 374 419 ... × 10  W⋅m ⋅K . Thus, when both luminosity and temperature are known (via direct measurement and calculation) the radius of a star can be determined. The spectra of galaxies look similar to stellar spectra, as they consist of the combined light of billions of stars. Doppler shift studies of galaxy clusters by Fritz Zwicky in 1937 found that the galaxies in

1230-400: Is absorbed by atmospheric water and carbon dioxide, so while the equipment is similar to that used in optical spectroscopy, satellites are required to record much of the infrared spectrum. Physicists have been looking at the solar spectrum since Isaac Newton first used a simple prism to observe the refractive properties of light. In the early 1800s Joseph von Fraunhofer used his skills as

1312-463: Is frequency. For this work, Ryle and Hewish were jointly awarded the 1974 Nobel Prize in Physics . Newton used a prism to split white light into a spectrum of color, and Fraunhofer's high-quality prisms allowed scientists to see dark lines of an unknown origin. In the 1850s, Gustav Kirchhoff and Robert Bunsen described the phenomena behind these dark lines. Hot solid objects produce light with

1394-407: Is longer, appearing redder than the source. Conversely, the wavelength of blueshifted light is shorter, appearing bluer than the source light: where λ 0 {\displaystyle \lambda _{0}} is the emitted wavelength, v 0 {\displaystyle v_{0}} is the velocity of the object, and λ {\displaystyle \lambda }

1476-676: Is now known as the Tholen classification , the C-types are made of carbonaceous material, S-types consist mainly of silicates , and X-types are 'metallic'. There are other classifications for unusual asteroids. C- and S-type asteroids are the most common asteroids. In 2002 the Tholen classification was further "evolved" into the SMASS classification , expanding the number of categories from 14 to 26 to account for more precise spectroscopic analysis of

1558-478: Is the Hubble Constant , and d {\displaystyle d} is the distance from Earth. Redshift (z) can be expressed by the following equations: In these equations, frequency is denoted by f {\displaystyle f} and wavelength by λ {\displaystyle \lambda } . The larger the value of z, the more redshifted the light and the farther away

1640-560: Is the observed wavelength. Note that v<0 corresponds to λ<λ 0 , a blueshifted wavelength. A redshifted absorption or emission line will appear more towards the red end of the spectrum than a stationary line. In 1913 Vesto Slipher determined the Andromeda Galaxy was blueshifted, meaning it was moving towards the Milky Way. He recorded the spectra of 20 other galaxies — all but four of which were redshifted — and

1722-461: Is the speed of light. Objects that are gravitationally bound will rotate around a common center of mass. For stellar bodies, this motion is known as peculiar velocity and can alter the Hubble Flow. Thus, an extra term for the peculiar motion needs to be added to Hubble's law: This motion can cause confusion when looking at a solar or galactic spectrum, because the expected redshift based on

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1804-454: The Doppler shift . Spectroscopy is also used to study the physical properties of many other types of celestial objects such as planets , nebulae , galaxies , and active galactic nuclei . Astronomical spectroscopy is used to measure three major bands of radiation in the electromagnetic spectrum: visible light , radio waves , and X-rays . While all spectroscopy looks at specific bands of

1886-703: The Greenwich 28 inch refractor in 1893. Leading up to and during the First World War (1914-18) the company produced periscopes for submarines and moved to St Albans in 1918. In 1925 the company was purchased by Charles Algernon Parsons , renamed Grubb Parsons, and moved to Newcastle upon Tyne . In the 20th century they produced large research telescopes including the Isaac Newton Telescope (1965), Anglo-Australian Telescope (1965) and UK Infrared Telescope (1979). Their final project

1968-405: The electron has either the same spin or the opposite spin of the proton . When the atom transitions between these two states, it releases an emission or absorption line of 21 cm. This line is within the radio range and allows for very precise measurements: Using this information, the shape of the Milky Way has been determined to be a spiral galaxy , though the exact number and position of

2050-416: The largest infrared telescope in the world), but not the mechanical parts. Smaller telescopes produced by Grubb Parsons in this period included the 1.0-metre (39 in) Jacobus Kapteyn Telescope (Roque de los Muchachos Observatory, 1979) and the optics for the 60-inch (1.5 m) Danish National Telescope ( La Silla Observatory , Chile, 1976). The company traded until 1985, with its last project being

2132-422: The spectrum of electromagnetic radiation , including visible light , ultraviolet , X-ray , infrared and radio waves that radiate from stars and other celestial objects. A stellar spectrum can reveal many properties of stars, such as their chemical composition, temperature, density, mass, distance and luminosity. Spectroscopy can show the velocity of motion towards or away from the observer by measuring

2214-577: The 1850s and 60s, the company also produced compound microscopes . With Thomas Grubb approaching retirement, in 1865 he was joined in managing the company by his son Howard Grubb . Thomas Grubb retired in 1868 and died in 1878. Howard Grubb solidified the company's reputation for high-quality optical instruments , and was knighted in 1887. The Grubbs contributed to the early development of astronomical spectroscopy by producing various spectroscopes . Surviving examples include spectroscopes with two and six prisms (the latter completed in 1867). In 1868

2296-642: The 4.2-metre (170 in) William Herschel Telescope . The surviving archives of the company are held at the Tyne and Wear Archives , part of the Discovery Museum in Newcastle. Ian Glass , a historian of astronomy , wrote a history of the company under the management of Thomas and Howard Grubb, based mostly on their letters. Glass also produced catalogues of the telescopes known to have been produced by Grubb and by Grubb Parsons. A partial history of

2378-719: The Cassegrain layout was innovative and had not been used on large telescopes before; it was widely adopted thereafter. Orders from outside Ireland soon followed, including the 6.7-inch (170 mm) Sheepshanks equatorial refractor for the Royal Observatory, Greenwich (London, 1838) and a 6.0-inch (150 mm) refractor for the United States Military Academy (West Point, 1840), both using lenses that had been produced by Cauchoix in Paris. In

2460-514: The Earth whilst the other moves away, causing a Doppler shift in the composite spectrum. The orbital plane of the system determines the magnitude of the observed shift: if the observer is looking perpendicular to the orbital plane there will be no observed radial velocity. For example, a person looking at a carousel from the side will see the animals moving toward and away from them, whereas if they look from directly above they will only be moving in

2542-516: The Irish astronomical community. His company would be officially be passed on to his son Thomas Grubb in 1916. What started as a general manufacturing firm would be formally renamed Grubb-Parsons by Sir Charles Parsons in 1925. The firm was instrumental to the war efforts in World War I and would change its focus from telescope making to aiding the allies in their war efforts. This would include

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2624-569: The asteroids. The spectra of comets consist of a reflected solar spectrum from the dusty clouds surrounding the comet, as well as emission lines from gaseous atoms and molecules excited to fluorescence by sunlight and/or chemical reactions. For example, the chemical composition of Comet ISON was determined by spectroscopy due to the prominent emission lines of cyanogen (CN), as well as two- and three-carbon atoms (C 2 and C 3 ). Nearby comets can even be seen in X-ray as solar wind ions flying to

2706-585: The company Grubb Parsons and moved the factory to Newcastle-upon-Tyne , where his other engineering companies were already located. The first large telescope completed under the new management (though not the first ordered) was a 36-inch (0.91 m) reflector for the Royal Observatory Edinburgh , which saw first light in 1930. A year later the Royal Greenwich Observatory ordered a copy of this instrument, which

2788-428: The company completed the 48-inch (1.2 m) Great Melbourne Telescope , one of the last large instruments to use a speculum primary mirror. It was the second largest telescope in the world at that time, and the largest that was fully steerable. In 1871 they produced a 18-inch (0.46 m) reflector, also using speculum, for the private observatory of William Huggins at Tulse Hill . A 24-inch (0.61 m) reflector

2870-431: The company under Parsons was written by its last managing director, George Sisson. Thomas Grubb Thomas Grubb (4 August 1800 – 16 September 1878) was an Irish optician and founder of the Grubb Telescope Company . He was born near Portlaw , County Waterford , Ireland, the son of William Grubb Junior, a prosperous Quaker farmer and his second wife, Eleanor Fayle. Thomas started out in 1830 in Dublin as

2952-426: The creation of gun-sights and submarine periscopes. The escalation of the war – particularly in 1916 – caused the firm to be under military guard. In 1918, the factory would be moved to St. Albans, England in fear that Grubb-Parsons would be vulnerable in the weaker Ireland. This shift of focus from the company from telescopes to the war effort marked a decrease in economic power that Irish astronomers held over

3034-427: The discovery of the 21-centimeter H I line in 1951. Radio interferometry was pioneered in 1946, when Joseph Lade Pawsey , Ruby Payne-Scott and Lindsay McCready used a single antenna atop a sea cliff to observe 200 MHz solar radiation. Two incident beams, one directly from the sun and the other reflected from the sea surface, generated the necessary interference. The first multi-receiver interferometer

3116-417: The distance to a galaxy, which may be a more accurate method than parallax or standard candles . The interstellar medium is matter that occupies the space between star systems in a galaxy. 99% of this matter is gaseous – hydrogen , helium , and smaller quantities of other ionized elements such as oxygen . The other 1% is dust particles, thought to be mainly graphite , silicates , and ices. Clouds of

3198-430: The dust and gas are referred to as nebulae . There are three main types of nebula: absorption , reflection , and emission nebulae. Absorption (or dark) nebulae are made of dust and gas in such quantities that they obscure the starlight behind them, making photometry difficult. Reflection nebulae, as their name suggest, reflect the light of nearby stars. Their spectra are the same as the stars surrounding them, though

3280-468: The early 1930s, while working for Bell Labs . He built a radio antenna to look at potential sources of interference for transatlantic radio transmissions. One of the sources of noise discovered came not from Earth, but from the center of the Milky Way , in the constellation Sagittarius . In 1942, JS Hey captured the Sun's radio frequency using military radar receivers. Radio spectroscopy started with

3362-577: The early years of our universe, with their extreme energy output powered by super-massive black holes . The properties of a galaxy can also be determined by analyzing the stars found within them. NGC 4550 , a galaxy in the Virgo Cluster, has a large portion of its stars rotating in the opposite direction as the other portion. It is believed that the galaxy is the combination of two smaller galaxies that were rotating in opposite directions to each other. Bright stars in galaxies can also help determine

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3444-555: The elements and molecules present in the atmosphere. To date over 3,500 exoplanets have been discovered. These include so-called Hot Jupiters , as well as Earth-like planets. Using spectroscopy, compounds such as alkali metals, water vapor, carbon monoxide, carbon dioxide, and methane have all been discovered. Asteroids can be classified into three major types according to their spectra. The original categories were created by Clark R. Chapman, David Morrison, and Ben Zellner in 1975, and further expanded by David J. Tholen in 1984. In what

3526-407: The elements present in a star and their relative abundances can be determined. Using this information stars can be categorized into stellar populations ; Population I stars are the youngest stars and have the highest metal content (the Sun is a Pop I star), while Population III stars are the oldest stars with a very low metal content. In 1860 Gustav Kirchhoff proposed the idea of a black body ,

3608-467: The exception of stars in the Milky Way and the galaxies in the Local Group , almost all galaxies are moving away from Earth due to the expansion of the universe . The motion of stellar objects can be determined by looking at their spectrum. Because of the Doppler effect , objects moving towards someone are blueshifted , and objects moving away are redshifted . The wavelength of redshifted light

3690-519: The following table. Designations from the early Balmer Series are shown in parentheses. Not all of the elements in the Sun were immediately identified. Two examples are listed below: To date more than 20 000 absorption lines have been listed for the Sun between 293.5 and 877.0 nm, yet only approximately 75% of these lines have been linked to elemental absorption. By analyzing the equivalent width of each spectral line in an emission spectrum, both

3772-422: The gas, imprinting the spectrum of the gas on that of the solid object. In the case of worlds with thick atmospheres or complete cloud or haze cover (such as the four giant planets , Venus , and Saturn 's satellite Titan ), the spectrum is mostly or completely due to the atmosphere alone. The reflected light of a planet contains absorption bands due to minerals in the rocks present for rocky bodies, or due to

3854-491: The global astronomers community and bolster Grubb's reputation. Unfortunately, the project would end in failure when the telescope was actually dismantled and shipped to Australia. Grubb was tasked of constructing a Cassegrain reflector that would include two 4-foot metal mirrors. The problem with the project was Grubb's choice of metal. This caused defects in the form of the astronomers in Melbourne being unable to re-polish

3936-532: The government of Ireland in 1866 to construct a telescope that would be sent to the southern hemisphere for use to compare the sky from there. This project would be known as the construction of the Melbourne Telescope. Grubb was tasked with mounting the telescope. He provided a large support to provide stability. The Royal Society Committee would go on to describe the telescope as 'a masterpiece of engineering'. This project would become renown amongst

4018-417: The holographic gratings are very versatile, potentially lasting decades before needing replacement. Light dispersed by the grating or prism in a spectrograph can be recorded by a detector. Historically, photographic plates were widely used to record spectra until electronic detectors were developed, and today optical spectrographs most often employ charge-coupled devices (CCDs). The wavelength scale of

4100-456: The horizontal plane. Planets , asteroids , and comets all reflect light from their parent stars and emit their own light. For cooler objects, including Solar System planets and asteroids, most of the emission is at infrared wavelengths we cannot see, but that are routinely measured with spectrometers . For objects surrounded by gas, such as comets and planets with atmospheres, further emission and absorption happens at specific wavelengths in

4182-626: The industry. A global shift to provide for the United States and the allies would change the scope of Grubb-Parsons forever. It is noted that during the war, Grubb-Parsons built around 95% of the periscopes in British submarines. Thomas died in 1878 in Monkstown, County Dublin , Ireland. He is buried at Mount Jerome Cemetery , Dublin , Ireland. Although the source of his death is unknown, he had been suffering from rheumatism since

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4264-558: The international Carte du Ciel project; the 13 inch refracting telescopes were designed to produce uniform photographic plates. In 1896 they produced a 30-inch (0.76 m) reflector for the Royal Observatory, Greenwich. The company produced an 18/24-inch double refractor for the Royal Observatory, Cape of Good Hope (South Africa, 1897) and a copy for the Radcliffe Observatory (Oxford, 1901). After

4346-601: The largest constructed in this period included a 24-inch (0.61 m) for the private observatory of William Edward Wilson (1881, Daramona House, Ireland); a 19-inch (0.48 m) heliostat for the Smithsonian Astrophysical Observatory (1890, Washington DC, USA); and the 28-inch (0.71 m) refractor at the Royal Observatory, Greenwich (1893, still the largest refractor in the UK). In 1887 Grubb's firm built seven identical astrographs for

4428-408: The light is bluer; shorter wavelengths scatter better than longer wavelengths. Emission nebulae emit light at specific wavelengths depending on their chemical composition. In the early years of astronomical spectroscopy, scientists were puzzled by the spectrum of gaseous nebulae. In 1864 William Huggins noticed that many nebulae showed only emission lines rather than a full spectrum like stars. From

4510-414: The light will be refracted at a different angle; this is dependent upon the indices of refraction of the materials and the wavelength of the light. By creating a "blazed" grating which utilizes a large number of parallel mirrors, the small portion of light can be focused and visualized. These new spectroscopes were more detailed than a prism, required less light, and could be focused on a specific region of

4592-419: The manufacturing firm changed its name to Grubb-Parsons in 1925. Thomas Grubb's reputation as a competent telescope maker began to spread as he offered his talents to the Irish astronomical community. Grubb first met the director of Armagh Observatory , Romney Robinson , sometime in the 1830s. His first commission was for E.J. Cooper of Markree Observatory . He was tasked to mount a 13.3 inch lens which

4674-520: The mechanical supports. Grubb provided an equatorial mount that could track targets automatically using a clock drive ; although this was not the first telescope with an equatorial mount, it was far larger than previous examples. This was followed in 1835 by a 15-inch (380 mm) reflecting telescope for Armagh Observatory (run by Robinson), which used the Cassegrain layout and another equatorial mount. The combination of an equatorial mount with

4756-554: The military contracts ended and peace returned in 1919, the company struggled to return to profitability. Howard Grubb, then in his 70s, attempted to revive the sale of large telescopes but the company began to lose money. Several telescopes had been delayed or not completed due to the war, such as a 24-inch (0.61 m) reflector for the National Astronomical Observatory of Chile (Santiago), which had been ordered in 1909, partially constructed in 1913, but

4838-574: The mirrors adequately. The last major work of Thomas Grubb's would start with him and end with his son Howard Grubb . In 1875, he would go on to build the Great Vienna Telescope. This would be known as the largest refracting telescope in the world up to that point. Thomas Grubb would begin his professional career in Dublin, Ireland in the year 1830 as a mechanical engineer. Here he would create telescopes that became infamous within

4920-568: The motion of the stars contained within them; the reason behind the lack of dark matter is unknown. In the 1950s, strong radio sources were found to be associated with very dim, very red objects. When the first spectrum of one of these objects was taken there were absorption lines at wavelengths where none were expected. It was soon realised that what was observed was a normal galactic spectrum, but highly red shifted. These were named quasi-stellar radio sources , or quasars , by Hong-Yee Chiu in 1964. Quasars are now thought to be galaxies formed in

5002-518: The object is from the Earth. As of January 2013, the largest galaxy redshift of z~12 was found using the Hubble Ultra-Deep Field , corresponding to an age of over 13 billion years (the universe is approximately 13.82 billion years old). The Doppler effect and Hubble's law can be combined to form the equation z = v Hubble c {\displaystyle z={\frac {v_{\text{Hubble}}}{c}}} , where c

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5084-492: The primary mirror for the 3.9-metre (150 in) Anglo-Australian Telescope (AAT) (at Siding Spring Observatory , Australia), which was completed in 1965, though its design and mounting were completed by other companies. Grubb Parsons also produced the 49-inch (1.2 m) UK Schmidt Telescope in 1973, located adjacent to the AAT. They produced the optical components of the 3.8-metre (150 in) UK Infrared Telescope (1979, then

5166-493: The simple Hubble law will be obscured by the peculiar motion. For example, the shape and size of the Virgo Cluster has been a matter of great scientific scrutiny due to the very large peculiar velocities of the galaxies in the cluster. Just as planets can be gravitationally bound to stars, pairs of stars can orbit each other. Some binary stars are visual binaries, meaning they can be observed orbiting each other through

5248-403: The spectrum by tilting the grating. The limitation to a blazed grating is the width of the mirrors, which can only be ground a finite amount before focus is lost; the maximum is around 1000 lines/mm. In order to overcome this limitation holographic gratings were developed. Volume phase holographic gratings use a thin film of dichromated gelatin on a glass surface, which is subsequently exposed to

5330-447: The spectrum, different methods are required to acquire the signal depending on the frequency. Ozone (O 3 ) and molecular oxygen (O 2 ) absorb light with wavelengths under 300 nm, meaning that X-ray and ultraviolet spectroscopy require the use of a satellite telescope or rocket mounted detectors . Radio signals have much longer wavelengths than optical signals, and require the use of antennas or radio dishes . Infrared light

5412-593: The spectrum. The chemical reactions that form these molecules can happen in cold, diffuse clouds or in dense regions illuminated with ultraviolet light. Most known compounds in space are organic , ranging from small molecules e.g. acetylene C 2 H 2 and acetone (CH 3 ) 2 CO; to entire classes of large molecule e.g. fullerenes and polycyclic aromatic hydrocarbons ; to solids , such as graphite or other sooty material. Stars and interstellar gas are bound by gravity to form galaxies, and groups of galaxies can be bound by gravity in galaxy clusters . With

5494-400: The spiral arms is the subject of ongoing research. Dust and molecules in the interstellar medium not only obscures photometry, but also causes absorption lines in spectroscopy. Their spectral features are generated by transitions of component electrons between different energy levels, or by rotational or vibrational spectra. Detection usually occurs in radio, microwave, or infrared portions of

5576-578: The standardisation of designs to be profitable, so continued the approach with a series of six near-identical 74-inch (1.9 m) telescopes for the David Dunlap Observatory (Ontario, Canada, 1935), Radcliffe Observatory (South Africa, construction completed 1938 but first light delayed until after the Second World War ), Mount Stromlo Observatory (Canberra, Australia, 1955), Haute-Provence Observatory (France, 1956, with

5658-413: The start of the 1870s. He had married Sarah Palmer. Their youngest son was Sir Howard Grubb , who took over the optical business. Thomas Grubb's cousin, John Grubb Richardson (1813 - 1891) was a major Irish industrialist who founded the model village of Bessbrook. Astronomical spectroscopy Astronomical spectroscopy is the study of astronomy using the techniques of spectroscopy to measure

5740-444: The submarine periscope was invented in 1902, Howard Grubb patented several improvements to their design. The Grubb factory began manufacturing the new instruments, which became their primary business by 1914. During the First World War , most British submarines were equipped with a periscope built by Grubb; following the 1916 Easter Rising in Dublin, the periscope workshop was moved to St Albans in 1918 for better security. When

5822-474: The work of Kirchhoff, he concluded that nebulae must contain "enormous masses of luminous gas or vapour." However, there were several emission lines that could not be linked to any terrestrial element, brightest among them lines at 495.9 nm and 500.7 nm. These lines were attributed to a new element, nebulium , until Ira Bowen determined in 1927 that the emission lines were from highly ionised oxygen (O ). These emission lines could not be replicated in

5904-473: Was able to calculate their velocities relative to the Earth. Edwin Hubble would later use this information, as well as his own observations, to define Hubble's law : The further a galaxy is from the Earth, the faster it is moving away. Hubble's law can be generalised to: where v {\displaystyle v} is the velocity (or Hubble Flow), H 0 {\displaystyle H_{0}}

5986-450: Was built in the same year by Martin Ryle and Vonberg. In 1960, Ryle and Antony Hewish published the technique of aperture synthesis to analyze interferometer data. The aperture synthesis process, which involves autocorrelating and discrete Fourier transforming the incoming signal, recovers both the spatial and frequency variation in flux. The result is a 3D image whose third axis

6068-572: Was constructed as the Yapp telescope . In 1931 the company provided both a 40-inch (1.0 m) reflector and a 24/20-inch double refractor for the new site of the Stockholm Observatory (Sweden). Charles Parsons died in 1931, but Grubb Parsons remained a subsidiary of his engineering business, C. A. Parsons and Company . In 1938, the company acquired the telescope manufacturing arm of Cooke, Troughton & Simms . The company found

6150-562: Was his own 9-inch (230 mm) refractor, which he operated as a public observatory in Portobello, Dublin , as a visitor attraction . The company's first order was the mount for the 13.3-inch (340 mm) telescope at Markree Observatory , completed in 1834 as the largest refracting telescope in the world. Edward Joshua Cooper , the owner of Markree Castle , had purchased the optics from Robert-Aglaé Cauchoix of Paris and commissioned Grubb (on Robinson's recommendation) to construct

6232-497: Was not operational until 1925. In 1925, with Howard Grubb aged 81 and the company on the verge of bankruptcy , it was sold to Charles Parsons . Parsons was an Anglo-Irish engineer with family connections to telescope making – Parson's father William Parsons had constructed the Leviathan of Parsonstown (the largest telescope in the world from 1845-1917). The families had been friends for two generations. Charles Parsons renamed

6314-427: Was produced for Royal Observatory, Edinburgh (1872, at Calton Hill Observatory ). The company constructed a 27-inch (0.69 m) refractor for the Vienna Observatory in 1878, which was then the largest refractor in the world and regarded as being of high optical quality. The Melbourne and Vienna telescopes substantially enhanced the reputation of the company, leading to numerous orders for new telescopes. Some of

6396-547: Was the William Herschel Telescope in 1985, after which the company shut down. The Grubb Telescope Company was founded in Dublin by the Irish engineer Thomas Grubb in 1833. He ran a precision engineering company whose cast iron products included billiard tables and printing presses for banknotes . Grubb had a personal interest in optics and was a friend of the Irish astronomer Thomas Romney Robinson . His first foray into telescope construction

6478-647: Was the 98-inch (2.49 m) Isaac Newton Telescope for Royal Greenwich Observatory , which had moved to Herstmonceux Castle , completed in 1965. The location was later deemed unsuitable, so from 1979-84 this telescope was moved to Roque de los Muchachos Observatory in the Canary Islands , during which Grubb Parsons upgraded it with a 100-inch (2.54 m) mirror. The company began to concentrate on optical systems, not mechanical designs, producing thousands of small mirrors, lenses and prisms for spectrometers as well as small telescopes. They ground and polished

6560-818: Was used to sketch Halley's comet in 1835 and to view the solar eclipse of 15 May 1836. Grubb's work at the Markree Observatory would become known as a milestone in the creation and handling of large-scale telescopes. In 1837, Thomas Grubb worked with fellow Irish scientist James MacCullagh . Together, they conducted a series of experiments on metallic refraction. Later he built telescopes for observatories worldwide, including Aldershot Observatory , Melbourne , Vienna, Madrid and Mecca and others. Thomas Grubb's company also made various scientific devices for Trinity College in Dublin. In 1839, his company made about twenty sets of magnetometers . These magnetometers were requested by Professor Humphrey Lloyd who

6642-514: Was used to view the solar eclipse of 15 May 1836. Grubb helped build the famous telescope for William Parsons, 3rd Earl of Rosse , at Parsonstown (now known as Birr) , County Offaly , Ireland. One of his earliest instruments - the telescope for Markree Observatory in County Sligo in the West of Ireland, supplied in 1834 - was, until 1839, the largest refracting telescope in the world. It

6724-457: Was very involved with Grubb's work. He sought Grubb's talents because so he could be close to the creation process and supervise his work. Starting from 1840, Grubb also worked as an engineer for the Bank of Ireland. He was responsible for designing machines used in the creation of banknotes. These machines were used for engraving, printing and numbering the banknotes. Grubb made a contract with

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