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Walter Baade Papers: Finding Aid
mssBaade papers  
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Collection Details
Table of contents What's This?
  • Overview of the Collection
  • Access
  • Administrative Information
  • Biographical Note
  • Arrangement
  • Indexing Terms

  • Overview of the Collection

    Title: Walter Baade Papers
    Date (inclusive): 1915-1960
    Collection Number: mssBaade papers
    Creator: Baade, Walter, 1893-1960.
    Extent: 22 boxes and one large folder
    Repository: The Huntington Library, Art Collections, and Botanical Gardens Manuscripts Department
    The Huntington Library
    1151 Oxford Road
    San Marino, California 91108
    Phone: (626) 405-2203
    Fax: (626) 449-5720
    Email: reference@huntington.org
    URL: http://www.huntington.org
    Abstract: The collection consists of research files and notes related to the study of supernovae, RR Lyrae stars, star populations, galaxies (including the Andromeda Galaxy), and various novae by German-born astronomer Wilhelm Heinrich Walter Baade (1893-1960), who joined the staff of the Mount Wilson Observatory in 1931. This collection forms part of the Mount Wilson Papers of the Observatories of the Carnegie Institution of Washington.
    Language: English.


    Open to qualified researchers by prior application through the Reader Services Department. For more information, contact Reader Services.

    Administrative Information

    Publication Rights

    The Huntington Library does not require that researchers request permission to quote from or publish images of this material, nor does it charge fees for such activities. The responsibility for identifying the copyright holder, if there is one, and obtaining necessary permissions rests with the researcher.

    Preferred Citation

    [Identification of item]. Walter Baade Papers, The Huntington Library, San Marino, California.


    Observatories of the Carnegie Institution of Washington, Deposit, 1988.

    Custodial History

    The amount of unpublished material Walter Baade left behind was great. This fact was realized among astronomers, and Jan Oort and Ira Bowen managed to collect his notes and measurements from Germany and parcel them out to his colleagues who were able to organize, reduce, and publish the material. Among those at the Mount Wilson and Palomar Observatories who aided in this were Henrietta Swope, Halton C. Arp, and Allan Sandage. Some material remains at the Leiden Observatory, but most of it was sent to Mt. Wilson. The bulk of Baade's papers, which were returned to Pasadena, were organized by Henrietta Swope and stored in the attic of the Mt. Wilson and Palomar Observatories office building. Her labels have been retained for the time being until Baade's papers are more fully catalogued.

    Biographical Note

    Wilhelm Heinrich Walter Baade (he did not often use his first two names) was one of the most important astronomers of the twentieth century. As an observer at the Mount Wilson Observatory, he ranks alongside Edwin Hubble in significance. Baade, however, was an excellent theoretician as well as observer. His interest in the stellar content of various star systems led him to develop his famous concept of stellar populations. And his observing skill led to his unexpected resolution of the inner parts of the Andromeda galaxy into individual stars. His work with the new 200-inch Hale telescope would eventually lead to a change in contemporary knowledge of the distances of the galaxies. Though his scientific method resulted in much of his work being published posthumously, Baade's impact on the development of astronomy was enormous.
    Walter Baade was born on March 24, 1893 at Schröttinghausen in Westphalia, Germany. His father Konrad, a schoolteacher, and his mother Charlotte, planned for Walter to pursue a career in theology. From 1903 to 1912 Baade attended the Friedrichs-Gymnasium in Herford with this end in mind. Over these years, however, Baade turned away from theology and toward science and mathematics. He attended the university at Münster from 1912 to 1913 and then continued at Göttingen until 1919. Baade studied mathematics, physics, and astronomy and spent his last four years at Göttingen as assistant to the great mathematician, Felix Klein. His Ph.D. dissertation in 1919 was on the spectrum of the double star, ß Lyrae.
    Upon receiving his degree, Baade went immediately into astronomical work. He obtained a position as an assistant at the Hamburg Observatory, being in charge of the 40-inch reflecting telescope. His abilities were soon recognized by others and in 1926 he received a Rockefeller International Education Board Fellowship to study in the United States and Canada. During the next year, Baade spent a great deal of time at the Harvard College Observatory, the Dominion Astrophysical Observatory, Yerkes, Lick, and Mount Wilson. The director of Mt. Wilson, Walter S. Adams, later noted that Baade's "ability and personal characteristics made a strong appeal to the members of our staff." Returning to Hamburg in 1927, Baade's responsibilities grew, and a year later he was offered the position as Chair of Astronomy at Jena, a position he turned down in order to remain at Hamburg and its better astronomical facilities. Baade was undoubtedly in line for the directorship at Hamburg, and in 1929 he became a Privatdozent at the University of Hamburg and was placed in charge of the observatory's eclipse expedition to the Philippines. However, in the opinion of many at the time, the current director at Hamburg, Richard Schorr, was too conservative and did not encourage Baade's research into newer and more promising fields of astrophysics. Instead, Baade had to be responsible for the less glamorous tasks such as confirming the positions of asteroids and comets. This was the situation in 1931 when Baade was offered a position as astronomer at the Mount Wilson Observatory. The Mt. Wilson astronomers realized that Baade was a young man of marked promise, capable of developing significant research programs. Even though Baade was reluctant to leave Germany the offer was one which Baade could not refuse and he joined the Mt. Wilson Observatory in October 1931.
    Baade quickly took up his photometric duties, trying to improve and extend the magnitudes in some of Kapteyn's selected areas. To his credit, however, he soon realized that the work of Stebbins and Whitford in obtaining accurate photoelectric magnitudes would be more valuable. As a result, he and Hubble encouraged the two astronomers to develop their system using the large telescopes on Mt. Wilson. Baade's main research thrust continued into the field of the stellar content of various stellar systems: clusters, galaxies, etc. This work would lead him to his important development of the idea of stellar populations.
    After Shapley's 1938 finding of a new type of stellar system, the dwarf elliptical galaxy, Baade and Hubble worked on resolving these systems into their constituent stars for the first time. World War II soon intervened, but in a bit of irony provided Baade with the best opportunity to continue his research. Before the war began, Baade had taken out papers to become an American citizen. After losing these papers while moving to a new house, he did not bother to renew his citizenship efforts. Consequently, when the war broke out Baade was declared an enemy alien and confined to Pasadena. After some appeals, the Observatory managed to get special permission for Baade to be at Mt. Wilson after dark in order to do research. Considering that most of the astronomers at Mt. Wilson were engaged in war work and that Los Angeles was often in a "brown out" situation to protect coastal shipping, Baade had plenty of time and darkness with which to use the 100-inch telescope. Under these conditions, and by using every means at his disposal, Baade achived what was then considered impossible with the 100-inch telescope: the resolution into stars of portions of the nucleus of the Andromeda galaxy (M31) and its two companions. With this accomplished, Baade was able to flesh out his concept of stellar populations. By the time of the International Astronomical Union's meeting in Rome in 1952, he was able to show evidence that there were two basic populations of stars: young, blue stars in dusty galactic regions (Population I) and older, redder stars in dust free regions (Population II)
    When Palomar Mountain's 200-inch telescope was put into operation in 1949, Baade was there to see if he could delve deeper into the stellar content of the Andromeda galaxy. Working to the limit of the telescope, Baade failed to discover a particular class of stars, known as RR Lyrae stars. According to the current knowledge of the intrinsic brightness of RR Lyrae stars, however, he should have been able to detect them with the 200-inch telescope. This led Baade to realize that the Andromeda galaxy was more distant than previously imagined. As a result of Baade's work, the size of the universe had to be roughly doubled. This result was announced at the same 1952 Rome meeting mentioned earlier.
    Baade was active in many fields of astronomy. One important one was his work to show that there was indeed a class of novae which were 10,000 times brighter than the classical novae. His results went far towards proving that these exceptionally brilliant exploding stars, called supernovae, did exist as a distinct phenomenon. Baade also studied historical supernovae, eventually discovering the remnant of Kepler's supernova of 1604 in the constellation Ophiuchus.
    Another field of research in which Baade entered was the optical identification of radio sources. As radio astronomy became more sophisticated, many astronomers began to chart the exact locations of celestial sources of radio waves. Baade, along with his colleague Rudolph Minkowski whom Baade had aided in leaving Germany and coming to Mt. Wilson in 1933, aided greatly in the effort to match these radio sources with optically visible objects, such as galaxies and supernova remnants.
    Baade also continued to occasionally pursue the asteroids, as he did at the Hamburg Observatory. In 1925 at Hamburg, he discovered Hidalgo (944), an asteroid whose orbit takes it farther from the Sun than any other known at the time. Then in 1944, he discovered another unusual minor planet, Icarus (1566), one of a few which occasionally pass near to the earth.
    In 1958, Baade retired from the Mt. Wilson and Palomar Observatories. Spending some time at Harvard and the Mount Stromlo Observatory in Australia, he returned to Germany in 1959 with his wife of thirty years, Johanna "Muschi" Bohlmann, and became Gauss professor at his old school, Göttingen. On June 25, 1960, while convalescing after an operation to correct his chronic hip problem, Baade suffered heart failure and died suddenly.
    Before he published any of his work, Baade always insisted on having enough observational evidence to leave his claims without any doubt. This explains why, after 1944, Baade published very little. The enormous task which Baade undertook, to unify stellar astronomy, left him too little time to collect enough evidence to publish his results before he died. However, Baade did not feel compelled to publish; he was always in constant contact with the leading astronomers, letting them know of his ideas and research. Paul Scherer, former executive officer of the Carnegie Institution of Washington once said, "We all recognize at the Institution that Baade publishes very little in the journals but we know for a fact that he is indeed one of the most prolific of our staff members. He 'publishes' his data by conversations in his office with the world's astronomers." Indeed, Baade's communication with others was so intense that he rearranged his office hours to enable him to work at home from 8 P.M. to 2 A.M.


    Arp, Halton Christian. "Wilhelm Heinrich Walter Baade, 1893-1960." Journal of the Royal Astronomical Society of Canada 55 (1961): 113-16.
    Dieke, Sally H. "Wilhelm Heinrich Walter Baade." Dictionary of Scientific Biography, C. C. Gillispie, ed. New York: Charles Scribner's Sons, 1970.
    Jackson, John. "The President's Address on the Award of the Gold Medal to Dr. Walter Baade." Monthly Notices of the Royal Astronomical Society 114 (1954): 370-83.
    Sandage, Allan R. "Wilhelm Heinrich Walter Baade." Quarterly Journal of the Royal Astronomical Society 2 (1961): 118-21.
    Sandage, Allan R. "Wilhelm Heinrich Walter Baade (1893-1960)." Year Book of the American Philosohical Society (1960): 108-13.
    Wilson, Olin Chaddock. "The Award of the Bruce Gold Medal to Dr. Walter Baade." Publications of the Astronomical Society of the Pacific 67 (1955): 56-61.

    Scope and Content Note

    The collection consists of research files, notes, and correspondence, related to the study of supernovae, RR Lyrae stars, star populations, galaxies (including the Andromeda Galaxy), and various novae by German-born astronomer Wilhelm Heinrich Walter Baade (1893-1960), who joined the staff of the Mount Wilson Observatory in 1931. This collection forms part of the Mount Wilson Papers of the Observatories of the Carnegie Institution of Washington.
    The collection has not been fully processed and the container list below provides only a broad description of materials in each box, often based on topics assigned by Henrietta Swope.
    Henrietta Swope's list included numbers for the following major headings in the container list below.

    Numbers assigned by Henrietta Swope

    • Marked photographs of galaxies and clusters of galaxies. Swope's number: 1 (Box 20)
    • Charts. Swope's number: 1 (Box 21)
    • Miscellaneous charts, graphs, and figures. Swope's number: 2 (Box 20)
    • Miscellaneous charts and graphs. Swope's number: 2 (Box 21)
    • Miscellaneous work from Germany before 1932. Swope's number: 3 (Box 1)
    • Miscellaneous work from Germany before 1932. Swope's number: 3 (Box 15)
    • Miscellaneous work from Germany before 1932. Swope's number: 4 (Box 2)
    • Cygnus variables work before 1934. Swope's number: 5 (Box 3)
    • Globular clusters. Swope's number: 6 (Box 4)
    • Extragalactic nebulae. Swope's number: 7 (Box 5)
    • Telescope programs & miscellaneous notes. Swope's number: 8 (Box 16)
    • Nova Aquilae 1918. Swope's number: 9 (Box 6)
    • Novae & Nova Herculis. Swope's number: 10 (Box 7)
    • Supernovae. Swope's number: 11 (Box 8)
    • Supernovae in galaxies. Swope's number: 12 (Box 9)
    • Crab nebula. Swope's number: 13 (Box 10)
    • Singer-Polignac Seminar 1939. Swope's number: 14 (Box 10)
    • Research Notes on B Cas & A Cas. Swope's number: 15 (Box 11)
    • Variables in field around NGC 6522. Swope's number: 16 (Box 12)
    • Card file on variables in field around NGC 6522, 1949-50. Swope's number: 17 (Box 11)
    • Population I & II; Type I & II Cepheids. Swope's number: 18 (Box 13)
    • Figures. Swope's number: 19 (Box 22)
    • Chart of expansion of B Cassiopeiae. Swope's number: 20 (Box 22)
    • Figures and chart of field of NGC 6522. Swope's number: 21 (Box 22)
    • R Aquarii. Swope's number: 22 (Box 17)
    • Miscellaneous. Swope's number: 23 (Box 17)
    • Notebook on novae. Swope's number: 24 (Box 17)
    • Letters after 1945. Swope's number: 25 (Box 19)
    • Supernova Ophiuchi 1604. Swope's number: 26 (Box 14)
    • Miscellaneous. Swope's number: 27 (Box 14)
    • Cygnus variables. Swope's number: 28 (Box 14)
    • C. Caratheodory: Geodetic Differential Equations (hand copy). Swope's number: 29 (Box 14)
    • Resolution of galaxies M31, 32, NGC205, 147, 185. Swope's number: 30 (Box 18)
    • Notes on Population I & II Cepheids 1950-60. Swope's number: 31 (Box 18)
    • Lectures. Swope's number: 32 (Box 19)
    • Papers for Michigan & IAU, etc. 1950-55. Swope's number: 33 (Box 19)
    • Lectures 1950-58. Swope's number: 34 (Box 18)
    • Lecture notes. Swope's number: 35 (Box 11)
    • "A Discussion of the Ursa Minor Dwarf Galaxy Based on Plates Obtained by Walter Baade," by van Agt. Swope's number: 36 (Box 19)
    • Letters (photocopies) of Baade: to/from F. G. Smith; to B. Lovell, 1951-52 re optical identification of various radio sources. Swope's number: 37 (Box 19)

    Related Material

    Approximately fifty additional separate collections form the Mount Wilson Papers of the Observatories of the Carnegie Institution of Washington and are available for research in the Huntington Library.


    Broadly arranged by subject, with oversize material housed in Boxes 20-22 and an oversize folder.

    Indexing Terms

    The following terms have been used to index the description of this collection in the Huntington Library's Online Catalog.  


    Baade, Walter, 1893-1960.
    Carnegie Institution of Washington.
    Mount Wilson Observatory -- History -- Sources.
    Astronomers -- California, Southern -- Archives.
    Astronomers -- Correspondence.
    Astronomy -- Research.
    RR Lyrae stars.
    Stars -- Populations.
    Stars, New.
    Andromeda Galaxy.


    Notes -- 20th century.
    Photographs -- 20th century.
    Research (document genres) -- 20th century.
    Technical reports -- 20th century.

    Added Entries

    Carnegie Institution of Washington.