Gart Westerhout (15 June 1927 – 14 October 2012) was a Dutch-American astronomer. Well before completing his university studies at Leiden, he had already become well-established internationally as a radio astronomer in the Netherlands, specializing in studies of radio sources and the Milky Way Galaxy based on observations of radio continuum emissions and 21-cm spectral line radiation that originates in interstellar hydrogen. He emigrated to the United States, became a naturalized citizen, and held a number of important scientific and management positions in academic and government institutions.
Westerhout was born in The Hague, and studied at the University of Leiden (Sterrewacht te Leiden) with Hendrik van de Hulst and Jan Hendrik Oort. Contemporaries and colleagues in the Netherlands included Hugo van Woerden, C. Lex Muller, Maarten Schmidt, Kwee Kiem King, Lodewijk Woltjer, and Charles L. Seeger, III (son of the ethnomusicologist, brother of Pete Seeger and half-brother of Mike Seeger). While they were students, Wim Brouw, Mike Davis, Ernst Raimond, Whitney Shane and Jaap Tinbergenworked with him.
He was awarded Physics and Astronomy degrees: Cand. (1950) and Drs. (1954) and was awarded a Ph.D. in Astronomy and Physics in 1958. Notable scientific achievements included: the significant Westerhout Catalogof continuum emission radio sources, by which "W" numerical designations such sources are still referenced (see for example Westerhout 49), done with the then-new Dwingeloo telescope; and his survey of neutral hydrogen in the outer parts of our Galaxy. His pioneering work, with colleagues, showed the first hints of spiral structure in the interstellar gas, revealed differential rotation in our Galaxy, and established a revised Galactic coordinate system still in use today.
While still at Leiden University, he held the posts of Assistant (1952–56), Scientific Officer (1956–59, and Chief Scientific Officer (1959–62). Arriving in 1962 as the first Director of a fledgling Astronomy Program at the University of Maryland (started by Uco van Wijk), he grew it into a major department granting masters and doctorate degrees. On the research side the Line Survey,Maryland-Green Bank Galactic 21-cm undertaken with the 91-m radio telescope of the National Radio Astronomy Observatory, not only extended to higher angular resolution our knowledge of Galactic structure, but also accomplished the training of graduate students who went on to notable achievements of their own.
He continued at Maryland in that role through 1973, with additional responsibilities from 1972-73 as Chairman of the Division of Mathematical & Physical Sciences and Engineering. From 1973 to '77 he was Professor of Astronomy at the University of Maryland, temporarily becoming Visiting Astronomer at the Max-Planck-Institut für Radioastronomie (MPIfR) in Bonn, Germany 1973-74.
From 1977-1993 he was Scientific Director at the U.S. Naval Observatory in Washington, DC. While there, he guided the evolution of that observatory toward astronomical data obtained from telescopes at the Flagstaff station, astrometric data produced by the techniques of radio interferometry and by innovative application of optical interferometry techniques (ground- and space-based.)
Together with his wife Judith, he had 5 children – Magda Cathleen, Gart, Bridget, Julian, and Anthony.
When Edward L. G. Bowell discovered asteroid 5105 Westerhout, he named it in Westerhout's honor.
Memberships include International Astronomical Union (IAU) (Commissions 33, 34, 40, 24 & 5), International Scientific Radio Union (URSI), American Astronomical Society (AAS), Royal Astronomical Society, and Sigma Xi.
He contributed his scientific and management expertise widely, for example to IAU, National Science Foundation (NSF), AAS, National Research Council, Associated Universities Inc., Inter-Union Committee for the Allocation of Frequencies (IUCAF), URSI, National Radio Astronomy Observatory, MPIfR, MIT's Haystack Observatory, Arecibo Observatory, National Academy of Sciences.
Awards and special recognition have included a NATO Fellowship, CSIRO (Australia) Fellowship, Award for the Teaching of Science, Washington Academy of Sciences, Humboldt Prize, Listings in : Outstanding Educators of America, American Men and Women in Science, Who's Who in America.
A. Papers published in refereed journals
l. Astronomy research
2. Instrumentation or techniques
B. Papers presented at scientific meetings
1. Invited papers
Proc. 9th Ann. PTTI meeting, NASA Tech. Mem. 78104, 1, 1978
2. Contributed papers
C. Books or contributions to edited books
D. Technical reports and others
The galactic coordinate system is a celestial coordinate system in spherical coordinates, with the Sun as its center, the primary direction aligned with the approximate center of the Milky Way Galaxy, and the fundamental plane parallel to an approximation of the galactic plane but offset to its north. It uses the right-handed convention, meaning that coordinates are positive toward the north and toward the east in the fundamental plane.
The Small Magellanic Cloud (SMC), or Nubecula Minor, is a dwarf galaxy near the Milky Way. Classified as a dwarf irregular galaxy, the SMC has a diameter of about 7,000 light-years, contains several hundred million stars, and has a total mass of approximately 7 billion solar masses. The SMC contains a central bar structure, and astronomers speculate that it was once a barred spiral galaxy that was disrupted by the Milky Way to become somewhat irregular. At a distance of about 200,000 light-years, the SMC is among the nearest intergalactic neighbors of the Milky Way and is one of the most distant objects visible to the naked eye.
The radial velocity of an object with respect to a given point is the rate of change of the distance between the object and the point. That is, the radial velocity is the component of the object's velocity that points in the direction of the radius connecting the point and the object. In astronomy, the point is usually taken to be the observer on Earth, so the radial velocity then denotes the speed with which the object moves away from the Earth.
Jan Hendrik Oort was a Dutch astronomer who made significant contributions to the understanding of the Milky Way and who was a pioneer in the field of radio astronomy. His New York Times obituary called him "one of the century's foremost explorers of the universe"; the European Space Agency website describes him as "one of the greatest astronomers of the 20th century" and states that he "revolutionised astronomy through his ground-breaking discoveries." In 1955, Oort's name appeared in Life magazine's list of the 100 most famous living people. He has been described as "putting the Netherlands in the forefront of postwar astronomy."
The hydrogen line, 21-centimeter line, or H I line is the electromagnetic radiation spectral line that is created by a change in the energy state of neutral hydrogen atoms. This electromagnetic radiation is at the precise frequency of 1,420,405,751.7667±0.0009 Hz, which is equivalent to the vacuum wavelength of 21.1061140542 cm in free space. This wavelength falls within the microwave region of the electromagnetic spectrum, and it is observed frequently in radio astronomy because those radio waves can penetrate the large clouds of interstellar cosmic dust that are opaque to visible light. This line is also the theoretical basis of the hydrogen maser.
The Dwingeloo Radio Observatory is a single-dish radio telescope near the village of Dwingeloo in the northeastern Netherlands. Construction started in 1954, and the telescope was completed in 1956. The radio telescope has a diameter of 25 m. At the time of completion it was the largest radio telescope in the world, but it was overtaken in 1957 by the 250 foot (76 m) Lovell Telescope.
In astronomy, an open cluster remnant (OCR) is the final stage in the evolution of an open star cluster.
The last of NASA's three High Energy Astronomy Observatories, HEAO 3 was launched 20 September 1979 on an Atlas-Centaur launch vehicle, into a nearly circular, 43.6 degree inclination low-Earth orbit with an initial perigeum of 486.4 km. The normal operating mode was a continuous celestial scan, spinning approximately once every 20 min about the spacecraft z-axis, which was nominally pointed at the Sun. Total mass of the observatory at launch was 2,660.0 kilograms (5,864.3 lb).
In astronomy Westerhout 49 also known as W49, is a strong galactic thermal radio source characteristic of an HII region. It was discovered by Gart Westerhout in 1958.
The Naval Observatory Vector Astrometry Software (NOVAS) is a software library for astrometry-related numerical computations. It is developed by the Astronomical Applications Department, United States Naval Observatory. Currently, NOVAS has three different editions for C, Fortran, and Python, respectively.
Propynylidyne is a chemical compound that has been identified in interstellar space.
Martha Patricia Haynes is an American astronomer who specializes in radio astronomy and extragalactic astronomy. She is the Goldwin Smith Professor of Astronomy at Cornell University. She has been on a number of high-level committees within the US and International Astronomical Community, including Advisory Committee for the Division of Engineering and Physical Sciences of the National Academies (2003–2008) and Astronomy and Astrophysics Decadal Review. She was a Vice-President of the Executive Committee of the International Astronomical Union from 2006–2012, and has been on the Board of Trustees of Associated Universities Inc since 1994.
Astrophysical X-ray sources are astronomical objects with physical properties which result in the emission of X-rays.
Pushchino Radio Astronomy Observatory is a Russian radio astronomy observatory. It was developed by Lebedev Physical Institute (LPI), Russian Academy of Sciences within a span of twenty years. It was founded on April 11, 1956, and currently occupies 70 000 square meters.
Arp-Madore 1 is a globular cluster visible in the constellation Horologium, located 123.3 kiloparsecs away from Earth. It is one of the most distant known globular clusters of the Milky Way galaxy's halo; its distance gives it interest as a test case for gravitational theories. It is named after Halton Arp and Barry F. Madore, who identified it as a distant globular cluster in 1979, using the UK Schmidt Telescope, after previous researchers at the European Southern Observatory had observed its existence but not its classification.
The Lockman Hole is an area of the sky in which minimal amounts of neutral hydrogen gas are observed. Clouds of neutral hydrogen glow faintly with infrared light and obscure distant views at extreme ultraviolet and soft x-ray wavelengths. They interfere with observations at those wavelengths in nearly all other directions since they are common in our galaxy. So the Lockman Hole serves as a relatively clear window on distant objects, which makes it an attractive area of the sky for observational astronomy surveys. It is located near the pointer stars of the Big Dipper in the constellation Ursa Major and is about 15 square degrees in size. It is named after its discoverer, astronomer Jay Lockman.
Prajval Shastri is an astrophysicist at the Indian Institute of Astrophysics, Bangalore and specializes in the area of phenomenology of active galaxies driven by supermassive blackholes using multi-wavelength observations ranging from radio to X-ray wavelengths.
Nancy Houk is an American astronomer who led the effort to establish a comprehensive database of stellar temperatures and luminosities.
Albert Bijaoui is a French astronomer, former student of the Ecole Polytechnique, renowned in image processing in astrophysics and its application in cosmology, he then prepared his PhD thesis at the Paris Observatory, under the supervision of André Lallemand. He defended his thesis at the Université Denis Diderot in March 1971.