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World War II, Esclangon retired from his position at the Paris
Observatory and Danjon replaced him. Here he taught at the Sorbonne. In the 1960s he persuaded the government to establish the European Southern Observatories at La Silla and at Paranal. He also supported the establishment of radio astronomy.at
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is visible is named after him. However, this limit may not exist. The Danjon effect is a name given for his observation that there is an increase in the number of "dark" total lunar eclipses during the 11 year solar sunspot maxima. He developed an astrolabe to identify irregularity in the rotational
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as director of the
Strasbourg Observatory. He was also appointed as a professor at Strasbourg University. In 1939, German invasion forced the move of faculty to Clermont-Ferrand near Vichy. He was arrested in November 1943 and he escaped being sent to Auschwitz and was released in January. After
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during which time he worked at the observatory of the
Societe Astronomique de France. He graduated in 1914 and was conscripted into the army during World War I. He served under Ernest Esclangon and lost an eye in combat in Champagne. He received war honours in 1915 and in 1919 he was appointed
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from 1945 to 1963. He developed several astronomical instruments to examine the regularity of the rotation of the earth and among his discoveries was an acceleration of the rotation of the Earth during periods of intense solar activity occurring in 11-year cycles correlated with an increase in
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to the
Strasbourg University. He took up duties as an observer at the Strasbourg Meridian observatory an began to work on the improvement of the observatory. He was involved in establishing a new observatory, the Observatoire de Haute-Provence which became operational in 1923.
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had the same apparent brightness as the earthlit portion on the unadjusted image, he could quantify the diaphragm adjustment, and thus had a real measurement for the brightness of earthshine. He recorded the measurements using his method (now known as the
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periodicity and concluded that there was increases in the Earth's rotation during intense solar activity. He suggested that the atmospheric darkness might be due to an increase in aerosols in the atmosphere due to increased volcanic activity.
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which is now known as the Danjon astrolabe, which led to an improvement in the accuracy of fundamental optical astrometry. An account of this instrument, and of the results of some early years of its operation, are given in Danjon's 1958
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Débarbat, Suzanne (2014). "Danjon, André-Louis". In Hockey, Thomas; Trimble, Virginia; Williams, Thomas R.; Bracher, Katherine; Jarrell, Richard A.; Marché, Jordan D., II; Palmeri, JoAnn; Green, Daniel W. E. (eds.).
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is used for measuring the intensity of lunar eclipses. He noted an increase in the number of dark lunar eclipses with solar activity which is termed as the Danjon effect.
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to drapers Louis
Dominique Danjon and Marie Justine Binet. He studied at the Lyce Malherbe and then went to the
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308:(SAF), the French astronomical society, during two periods: 1947–49 and 1962–64. He was awarded the
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in 1958. In 1946 he was made
Officier of the Legion d'Honneur and in 1954 he was made Commandeur.
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423:"George Darwin Lecture. The contribution of the impersonal astrolabe to fundamental astronomy"
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Danjon, A. (1921). "Relation entre l'éclairement de la lune éclipsée et l'activité solaire".
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Among his notable contributions to astronomy was the design of the impersonal (prismatic)
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split the Moon's image into two identical side-by-side images. By adjusting a
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of Venus and
Mercury which became the subject of his doctoral dissertation
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Recipients of the Gold Medal of the Royal
Astronomical Society
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Fehrenbach, C. "Un grand astronome : André Danjon."
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List of presidents of the Société astronomique de France
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of the Société astronomique de France in 1950, and the
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The "Danjon limit", a proposed measure of the minimum
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based on an earlier prismatic astrolabe developed by
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697:Presidents of the International Astronomical Union
454:"Study of Danjon limit in moon crescent sighting"
427:Monthly Notices of the Royal Astronomical Society
244:(1928) at Paris University. In 1930 he succeeded
682:Academic staff of the University of Strasbourg
577:Bibliothèque nationale de France: Danjon André
493:"Danjon Effect, Solar Activity, and Volcanism"
296:between the Sun and the Moon at which a lunar
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611:This article about a French astronomer is a
406:: CS1 maint: multiple names: editors list (
378:. New York, NY: Springer. pp. 504–506.
314:Gold Medal of the Royal Astronomical Society
112:Gold Medal of the Royal Astronomical Society
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667:Members of the French Academy of Sciences
376:Biographical Encyclopedia of Astronomers
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491:Komitov, B. P.; Kaftan, V. I. (2022).
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242:Recherches de photometrie astronomique
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207:Danjon devised a method to measure "
227:to dim one of the images until the
615:. You can help Knowledge (XXG) by
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345:"direction de Danjon (1945-1963)"
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304:Danjon was the President of the
662:20th-century French astronomers
458:Astrophysics and Space Science
306:Société astronomique de France
286:Quito Astronomical Observatory
169:who served as director of the
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567:, 1967, Vol. 81, pp. 323-331.
384:10.1007/978-1-4419-9917-7_331
173:from 1930 to 1945 and of the
27:French astronomer (1890–1967)
280:Danjon Prismatic Astrolabe (
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271:Royal Astronomical Society
509:10.1134/S001679322208014X
497:Geomagnetism and Aeronomy
470:10.1007/s10509-012-1004-y
452:Hasanzadeh, Amir (2012).
211:" on the darkside of the
171:Observatory of Strasbourg
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196:Ecole Normale Superieure
162:[ɑ̃dʁelwidɑ̃ʒɔ̃]
702:French astronomer stubs
319:Danjon died in 1967 in
262:François Auguste Claude
421:Danjon, Andre (1958).
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349:Observatoire de Paris
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672:Scientists from Caen
439:1958MNRAS.118..411D
190:Danjon was born in
310:Prix Jules Janssen
294:angular separation
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154:André-Louis Danjon
34:André-Louis Danjon
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393:978-1-4419-9917-7
178:earthquakes. The
175:Paris Observatory
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120:Scientific career
16:(Redirected from
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102:Danjon scale
75:(1967-04-21)
59:6 April 1890
18:André Danjon
692:1967 deaths
687:1890 births
219:in which a
88:Nationality
656:Categories
538:: 261–265.
532:Astronomie
433:: 411–31.
331:References
209:earthshine
167:astronomer
55:1890-04-06
517:0016-7932
478:0004-640X
402:cite book
284:, 1954).
258:astrolabe
253:in 1956.
225:diaphragm
217:telescope
130:astronomy
321:Suresnes
298:crescent
215:using a
81:Suresnes
435:Bibcode
158:French:
114:in 1958
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251:Nancay
238:albedo
126:Fields
108:Awards
92:French
221:prism
613:stub
513:ISSN
474:ISSN
408:link
388:ISBN
213:Moon
192:Caen
70:Died
63:Caen
49:Born
505:doi
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380:doi
282:OPL
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