Dennis Walsh (12 June 1933 – 1 June 2005) was an

English English usually refers to: * English language * English people English may also refer to: Peoples, culture, and language * ''English'', an adjective for something of, from, or related to England ** English national ide ...

astronomer An astronomer is a scientist in the field of astronomy who focuses their studies on a specific question or field outside the scope of Earth. They observe astronomical objects such as stars, planets, moons, comets and galaxies – in either ...

. He was an early

radio astronomer Radio astronomy is a subfield of astronomy that studies celestial objects at radio frequencies. The first detection of radio waves from an astronomical object was in 1933, when Karl Jansky at Bell Telephone Laboratories reported radiation coming ...

, as well as an optical astronomer. He was best known for his discovery in 1979 of the first example of a

gravitational lens A gravitational lens is a distribution of matter (such as a cluster of galaxies) between a distant light source and an observer that is capable of bending the light from the source as the light travels toward the observer. This effect is known ...

, B0957+561, using an optical telescope.

Personal life

He was born into a poor family in Dukinfield, east of

Manchester Manchester () is a city in Greater Manchester, England. It had a population of 552,000 in 2021. It is bordered by the Cheshire Plain to the south, the Pennines to the north and east, and the neighbouring city of Salford to the west. The t ...

. He married Pamela Lawton in 1957, with whom he had four sons, named Colin, Timothy, Paul and Brian (the latter three born in the USA). Dr. Walsh taught and also oversaw 16 Ph.D courses for various students, including one who would later go on herself to teach acclaimed British physicist and maker of documentaries, Brian Cox. In his last years Dr. Walsh suffered from Lewy body disease. He died at home at the age of 71.

Career

He developed an early aptitude for mathematics and

physics Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...

. He received a scholarship from the

University of Manchester , mottoeng = Knowledge, Wisdom, Humanity , established = 2004 – University of Manchester Predecessor institutions: 1956 – UMIST (as university college; university 1994) 1904 – Victoria University of Manchester 1880 – Victoria Univ ...

, where he received a first class honours degree in Physics at the age of 19. In 1953 he started studying for a PhD from

Jodrell Bank Jodrell Bank Observatory () in Cheshire, England, hosts a number of radio telescopes as part of the Jodrell Bank Centre for Astrophysics at the University of Manchester. The observatory was established in 1945 by Bernard Lovell, a radio astro ...

, supervised by

Robert Hanbury Brown Robert Hanbury Brown, AC FRS (31 August 1916 – 16 January 2002) was a British astronomer and physicist born in Aruvankadu, India. He made notable contributions to the development of radar and later conducted pioneering work in the field of ...

, where he constructed a 92MHz receiver for the

Transit Telescope In astronomy, a transit instrument is a small telescope with extremely precisely graduated mount used for the precise observation of star positions. They were previously widely used in astronomical observatories and naval observatories to meas ...

. Working with

Cyril Hazard Cyril Hazard is a British astronomer. He is known for revolutionising quasar observation with John Bolton in 1962. His work allowed other astronomers to find redshifts from the emission lines from other radio sources. Early work Cyri Hasard was b ...

, he used the receiver to carry out a radio source survey, detecting 134 sources. The survey was limited by source confusion, an issue that Dennis and Cyril identified for the first time. He completed his PhD in 1957. He worked for

Ferranti Ferranti or Ferranti International plc was a UK electrical engineering and equipment firm that operated for over a century from 1885 until it went bankrupt in 1993. The company was once a constituent of the FTSE 100 Index. The firm was known ...

for a short time, before moving to the

University of Michigan , mottoeng = "Arts, Knowledge, Truth" , former_names = Catholepistemiad, or University of Michigania (1817–1821) , budget = $10.3 billion (2021) , endowment = $17 billion (2021)As o ...

in 1959 to teach and to research low-frequency radio emission in the ionosphere, for which he used sounding rockets. He returned to the

in 1967 in order to work on atmospheric research using the Ariel 3 satellite, and to lead the "survey group", while supervising PhD students. He used a wide variety of

optical telescope An optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through elect ...

s, having learnt about optical observing using the

Isaac Newton Telescope The Isaac Newton Telescope or INT is a 2.54 m (100 in) optical telescope run by the Isaac Newton Group of Telescopes at Roque de los Muchachos Observatory on La Palma in the Canary Islands since 1984. Originally the INT was situated at He ...

, before being one of the first western astronomers to use the Soviet

BTA-6 The BTA-6 (russian: Большой Телескоп Альт-азимутальный, translit=Bolshoi Teleskop Alt-azimutalnyi, translation=Large Altazimuth Telescope) is a aperture optical telescope at the Special Astrophysical Observatory lo ...

telescope. The Jodrell Bank 966MHz survey was led by the survey group at Jodrell Bank. Walsh's spectroscopic follow-up of quasars in this survey led to the 1979 discovery of the first example of a

, B0957+561, using an optical telescope at the

Kitt Peak National Observatory The Kitt Peak National Observatory (KPNO) is a United States astronomical observatory located on Kitt Peak of the Quinlan Mountains in the Arizona-Sonoran Desert on the Tohono Oʼodham Nation, west-southwest of Tucson, Arizona. With more than ...

. Dr. Walsh was a long serving council member of the

Royal Astronomical Society (Whatever shines should be observed) , predecessor = , successor = , formation = , founder = , extinction = , merger = , merged = , type = NG ...

, where he held the post of Treasurer from 1988 for eight years. He organised the finances for the

International Astronomical Union The International Astronomical Union (IAU; french: link=yes, Union astronomique internationale, UAI) is a nongovernmental organisation with the objective of advancing astronomy in all aspects, including promoting astronomical research, outreac ...

's General Assembly meeting in Manchester in August 2000.

References

{{DEFAULTSORT:Walsh, Dennis 1933 births 2005 deaths People from Dukinfield 20th-century British astronomers University of Michigan faculty