Fonds 1109 - Tom Bolton fonds

Identity area

Reference code

UTA 1109


Tom Bolton fonds


  • 1935 - 2010 (Creation)

Level of description


Extent and medium

10.44m of textual records (33 boxes)
20 photographs (1 box)

Context area

Name of creator

(1943 - 2021)

Biographical history

Charles Thomas (Tom) Bolton (15 April 1943 – 4 February 2021) was an astronomer and Professor Emeritus at the University of Toronto’s Department of Astronomy and Astrophysics. Academically, he is best known as one of the first astronomers to discover observational proof of the existence of black holes. He is also known internationally for his fight against light pollution in Richmond Hill, which led to the establishment of the first municipal light pollution regulation in Canada.

Bolton was born in Camp Forrest, a World War II military base east of Tullahoma, Tennessee. He was raised in Illinois where he later completed his B.Sc. in Astronomy at the University of Illinois in 1966. Afterwards, he received his M.Sc. (1968) and Ph.D. (1970) from the University of Michigan during which he became an expert in astronomical spectroscopy. His doctoral thesis, Spectral Synthesis of Low Dispersion Luminosity Criteria in A and F Type Stars was supervised by Charles R. Cowley. In September 1970, Bolton began a postdoctoral fellowship at the University of Toronto where he worked with Robert Garrison and John Heard on spectral classification and radial velocity research programs at the David Dunlap Observatory (DDO).

While working as a postdoc, Bolton began teaching as an adjunct professor at the University of Toronto’s Department of Astronomy (1970 – 1971), Scarborough College (1971 – 1972), and Erindale College (1972 – 1973). In 1973, he was hired as an Assistant Professor (1973 – 1976) before becoming an Associate Professor (1976 – 1980), eventually receiving full tenure in 1980. Throughout his career, Bolton served on numerous committees within the Department of Astronomy, including the Chant Committee (1978 – 1979), Colloquium Committee (1985 – 1986), Graduate Program Degree Committee (1992 – 1993), Curriculum Review Committee (1990 – 1991), Executive Committee (1991 – 1994), as well as several search and tenure committees at the departmental and university levels.

Bolton’s research primarily involved the spectroscopic observation of stars, with a particular focus on hot massive stars, variable stars, binary systems, and stars with strong magnetic fields or peculiar chemical properties. His success as an astronomer began early in his academic career. In 1970, as a pioneer of spectral synthesis, Bolton developed a computer model for stellar atmospheres capable of generating large regions of spectra that were comparable to spectral data from real stars. This technique would eventually become part of the standard skillset of stellar astronomers.

Shortly after, in 1972, Bolton presented his most celebrated contribution to astronomy when he discovered and published the first irrefutable evidence for the existence of a black hole in the x-ray source, Cygnus X-1. Much of Bolton’s subsequent work has also contributed heavily to the field’s understanding of stellar evolution. His work has been published in over 100 academic journal articles, often co-authored by his students or collaborating astronomers from around the world.

In addition to his research, Bolton dedicated much of his time to administrative roles and improving the facilities at the DDO. He served as the DDO’s Associate Director (1978 – 1994) as well as the supervisor of the 74-inch telescope (1974 – 1984) and darkroom (1976 – 1983). Between 1970s and 1990s, Bolton led several campaigns to upgrade and modernize the equipment at the observatory including the acquisition of a PDS microdensitometer, an image slicer for the cassegrain spectrograph, and a CCD camera for the 74-inch telescope. He also chaired numerous committees, including the Telescope Scheduling Committee (1971 – 1984); Shop Committee (1982 – 1983; 1992 – 1994); Safety Committee (1981 – 1994); and the DDO Review Committee (1992 – 1997).

As the DDO’s Light Pollution Officer (1972 – 1997), Bolton fought against the rapidly increasing levels of light pollution in the Greater Toronto Area which threatened the DDO’s ability to conduct research. By 1986, Bolton succeeded in generating enough negative publicity against developers in the Town of Richmond Hill that the Town
agreed to pass a light pollution abatement by-law and authorized Bolton to review and approve the lighting plans for all new developments until the by-law could be implemented. During this time, Bolton also helped to draft the by-law which was established as the first of its kind in Canada in 1995.

Outside his role at the University of Toronto, Bolton was also highly involved in the broader astronomical community. He was a founding member of the Canadian Astronomical Society (CAS) and an active member of the International Astronomical Union (IAU), Royal Astronomical Society of Canada (RASC), American Astronomical Society (AAS), Planetary Society, and the Illumination Engineering Society (IES). Within the IAU, Bolton served on Divisions G (Stars and Stellar Physics) and V(Variable Stars), as well as numerous commissions and committees including Commission 30: Radial Velocities (1976 – 1988), Commission 42: Close Binary Stars (1979 – 2015), and Commission 27: Variable Stars (1982 – 2015). Beginning in the late 1970s, Bolton also served on several peer review, scientific advisory, and observing time assignment committees for NASA’s International Ultraviolet Explorer (IUE), Hubble Space Telescope, Extreme Ultraviolet Explorer (EUVE); the Canada-France-Hawaii Telescope; the Canadian Space Agency (CSA); the National Research Council of Canada; and the Natural Sciences and Engineering Research Council of Canada (NSERC). Likewise, Bolton was passionate about public education and outreach, giving over 100 interviews for television, radio, and newspapers, as well as public talks about astronomy throughout his career.

In the early 1990s, Bolton began experiencing several health issues that forced him to take extended sick leaves and eventually, a long-term disability leave in 1997. In July 1992, Bolton was deeply impacted by the suicide of his Ph.D. student and friend, Michael Fieldus, who was within a couple of months of completing his degree. Bolton, along with the Fieldus family, petitioned to have the University grant Fieldus’ degree posthumously and worked to complete Fieldus’ thesis using the data that Fieldus had collected. Although Bolton had been able to convince the School of Graduate Studies that Fieldus’ situation would warrant consideration, the request was ultimately denied. After Fieldus’ death Bolton helped to establish the Michael S. Fieldus Award presented to students in the department who exemplified Fieldus’ leadership and academic excellence.

In 2007, the University of Toronto announced the plan to sell the DDO and the surrounding property for development. Distressed by the University’s decision, Bolton became a founding member of the DDO Defenders, a community group which sought to protect and conserve the DDO property. The efforts of Bolton and the DDO Defenders resulted in the designation of the DDO as a heritage site under the Ontario Heritage Act in 2009 and a National Historic Site of Canada in 2019. However, the sale of the DDO in June 2008 forced Bolton to vacate the Observatory. This put an early end to his career as his health issues prevented him from travelling to work at other observatories. Bolton retired and was appointed Professor Emeritus status in 2008.

Bolton was born to Clifford T. and Pauline (Voris) Bolton in 1943. Prior to moving to Toronto, Bolton was married to Mary Jean Harris, separating in the mid-to-late 1970s. In 1985, Bolton met amateur astronomer Carolyn Susan Challenger through the RASC in Toronto. The couple married in 1986 and Bolton became a stepfather to her four children, David, Stephen, Craig, and Bill Hodges. Challenger died on December 7th, 2012 and Tom Bolton died on February, 4th 2021at his home in Richmond Hill.

The way archival record creators identify themselves and are identified by others is key to understanding the perspectives and content of their records. Tom Bolton was socially understood as a white man. Additional information from the creator or family members was not provided.


ASTROLab of Mont-Mégantic National Park. (n.d.). Charles Thomas Bolton (1943-). Canada Under the Stars.

Bolton, C. T. (2002). A Personal View of Combating Light Pollution. The Doings of the Department of Astronomy & Astrophysics and the David Dunlap Observatory, 33(2).

David Dunlap Observatory Defenders. (2012, April 12). Public Statement from the David Dunlap Observatory Defenders, Richmond Hill, Ontario.

Fullerton, A. W., Gies, D. R., & Shore, S. N. (2021). Obituary: Charles Thomas Bolton (1943–2021). Bulletin of the American Astronomical Society, 53(2).

Obituary: Pauline Bolton. (1992, July 15). The Pantagraph, C5.

Percy, J. R. (2021, February 19). Obituary: Astronomer Tom Bolton found compelling evidence of a black hole's existence: He became something of a celebrity through his ground-breaking work on X-ray-emitting Cygnus X-1, which inspired a song series by the rock band Rush. The Globe and Mail.

Vinas, M. J. (2008, July 25). Despite Protests, U. of Toronto Closes Observatory. The Chronical of Higher Education, 54(64), A6.

Name of creator


Biographical history

Michael Stewart Fieldus (11 October 1962 – 4 July 1992) was a Ph.D. student at the University of Toronto’s Department of Astronomy. His doctoral research focused on the line profile variations in the spectra of B stars.

Michael Fieldus was born in Toronto, Ontario to Paul and Beryl Fieldus. He began his undergraduate studies at the University of Toronto in the early 1980s. During this time, Fieldus became acquainted with Dr. Tom Bolton, who eventually became a friend and mentor. The two first met in 1982 when Fieldus enrolled in Bolton’s course, AST 323: Spherical Astronomy and Celestial Mechanics, and again the next year in Bolton’s AST 321: Solar System Astrophysics. In his final year, Fieldus completed an undergraduate thesis under the supervision of Dr. Bolton which analyzed the accuracy of PROCOR, a radial velocity correlation program, at the David Dunlap Observatory (DDO). Fieldus received his B.Sc. in 1986 and continued at the University of Toronto to pursue a graduate degree under the supervision of John Lester and Chris Rogers. He received his MSc (1989) in Astronomy for his thesis, A Program for Spherically Extended Line Blanketed Model Atmospheres, which Dr. Bolton has described as, “one of the pioneering works in its field.”

Remaining at U of T, Fieldus began his Ph.D. under the supervision of Dr. Bolton in 1989. His doctoral thesis, A Survey of Line Profile Variability in Non-Emission Lined B0-B5, V-III Star, sought to determine the incidence and properties of line profile variations of slowly pulsating B stars as a function of fundamental stellar parameters.

Fieldus died by suicide on July 4, 1992. Only a couple of months away from completing his doctoral work, Bolton and Fieldus’ family requested that the University grant the degree posthumously. The request was ultimately refused despite Bolton’s efforts to complete the thesis. Fieldus’ friends and family later established the Michael S. Fieldus Memorial Award in his honor.

Prior to his death, Fieldus published several abstracts, conference papers, and reviewed academic articles published in Astronomy and Astrophysics, The Astrophysics Journal, and The Astrophysics Journal Letters. He was honoured with several fellowships and awards to support his work including the Frank S. Hogg Fellowship (1986 – 1987), Carl Reinhardt Fellowship (1987 – 1988), C.A. Chant Fellowship (1988 - 1989), U of T Open Doctoral Fellowship (1998 – 1991), Department of Astronomy Scholarship (1991), Ontario Graduate Scholarship (1991 – 1992), and an NSERC postdoctoral fellowship (1992).

Outside his research and education, Fieldus was an active member of the U of T community. During his undergrad he joined the men’s swim team and later became the team captain and the swimming representative of the Men’s T-Holder’s Association.

While a student, Fieldus was involved in the Graduate Astronomy Students Association (GASA) serving as President (1989 – 1990) and student representative at faculty meetings (1989 – 1992). Fieldus was also a humor and gossip columnist for the “GASA Gossip” segment of the Department of Astronomy’s quarterly newsletter, The David Dunlap Doings from 1986 until his death. Additionally, he dedicated his time to the DDO where he worked as a research assistant and summer tour guide.

The way archival record creators identify themselves and are identified by others is key to understanding the perspectives and content of their records. Michael Fieldus was socially understood as white. Information was gathered by the archivist from photographic records. No additional information was provided by the creator or family members.

Archival history

The records of both Tom Bolton and Michael Fieldus were transferred to UTARMS as a single set of records as Bolton had stored and preserved Fieldus’ work following his death.

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Scope and content

Fonds consists of records of both Professor Tom Bolton and his former doctoral student, Michael Fieldus, documenting their respective research and academic careers. Material predominantly covers the activities of Bolton, including his research on stellar spectroscopy and other topics, teaching, administrative and committee duties for the Department of Astronomy and the David Dunlap Observatory, publishing activity, and his involvement in both professional associations and as an advisor to government bodies on topics such as light pollution. The records of Michael Fieldus cover his student work and research. Particular focus is given to his Ph.D. research, which discussed the changes observed in the shape and intensity of spectral lines emitted by B-type stars over time. Following Fieldus’ death, Bolton completed this research which has created some overlap between the two creators’ records. Please see sous-fonds descriptions for additional detail.

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All files are open, with the following exceptions:

  • Series 2: B2023-0003/004(01)-(24)
  • Sub-series 3.1: B2023-0003/004(32)
  • Sub-series 3.2 - all files restricted; B2023-0003/005(09)-(17)
  • Sub-series 4.1: B2023-0003/005(19), (21), (23), (25), (28)
  • Sub-series 4.2: B2023-0003/007(01)

Please see series and sub-series descriptions for additional information.

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  • Finding aid by Ashley Buttineau, September 2023
  • Added to AtoM by Sarah Paiva and Emily Sommers, June 2024




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