The Williamina Fleming Collection of Astronomical Glass Plate Photographs

Plate A01271 - a glass plate negative showing the Great Nebula in Orion and notations - the background is white and the nebula looks like a black flower blooming in a sea of black stars
Plate A01271 showing the Great Nebula in Orion. 

Collection Inventory

A listing of collection records can be accessed here. The spreadsheet is free-text searchable and can be sorted by plate number. 

Summary Information

Repository: The John. G. Wolbach Library

Identifier: HCO-FLEM

Creator: Harvard College Observatory

Title: The Williamina Fleming Collection of Astronomical Glass Plate Photographs

Date: 1886-1973

Language: English

Overview: The Williamina Fleming Collection of Astronomical Glass Plate Photographs represent the most significant plates used in the discoveries, research, and work process of the Women Computers and astronomers at Harvard College Observatory.

Conditions Governing Access: The collection is open for research use. 

Physical Access: The Wolbach Library and the Plate Stacks are located at the Harvard-Smithsonian Center for Astrophysics, however, many records and special collection items are stored off-site. Please contact us at least two weeks prior to visiting to ensure that records can be made available upon arrival. Researchers visiting Wolbach Library must abide by the Visiting Researcher Rules and handling practices.

Processing Information: This finding aid was created in the spring of 2022 by Lisa Bravata, Sarah Lavallee, and Meta Partenheimer.

The glass plates identified for The Williamina Fleming Collection originated from the Harvard College Observatory Astronomical Photographic Glass Plate Collection, which houses more than 550,000 glass plate photographs. 

Plate numbers are original and were assigned by the observatory when the photograph was taken. Item titles have been devised by the archivist and are based on the individuals who worked with the plates, the content of the plates, and notable features of the plates. 

The glass plates in this collection were housed historically in the Observatory Plate Stacks and arranged by date or by astronomical coordinates. The Williamina Fleming Collection plates were rehoused into archival boxes and relocated to a climate controlled environment in April, 2022. 

This is a working document and additional information will be added as the records are processed to a more granular level. 

Related Archival Materials:

  • Harvard College Observatory Astronomical Photographic Glass Plate Collection (1885-1992), Subseries I.A. Astronomical Glass Plate Photographs (unpublished as of May 27, 2022)
  • Harvard College Observatory observations, logs, instrument readings, and calculations. (KG11365-6)
  • Journal of Williamina Paton Fleming, 1900 Mar.1-Apr. 18: curator of astronomical photographs, Harvard College Observatory (HUA 900.11)
  • Papers of Williamina Paton Fleming, 1905-1909 (HUG 1396)
  • Additional records of the Harvard College Observatory can be found in the Harvard University Archives under collection identifier UAV 630.xx.
  • Archival collections for many of the individuals who also worked with this collection are held at Harvard University Archives, The Schlesinger Library, and other repositories outside of Harvard. 

Collection Information

Extent: 633 glass plate negatives 

Physical Description: The astronomical glass plate photographs are kept in historic jackets or have been rehoused in archival jackets. Most plates are sized 8x10”. Plates in Series A are  14x17” and there are a small quantity of plates sized 8x8”, 5x8”, and 4x5”.  The Williamina Fleming Collection also includes a few round plates with an 8” diameter. 

Some plates have been damaged over their lifetime. Examples of damage to plates may include water damage from an incident in 2016 involving a water main burst, aluminum and adhesive deterioration, and failing emulsion. Broken and mended plates are also present.

Scope and Contents: The Williamina Fleming Collection comprises 679 glass plate photographs which represent the discoveries, research, and work process of the Women Computers and astronomers at Harvard College Observatory. These telescope images originated from Harvard astronomers’ frequent and systematic survey of the sky in both the northern and southern hemispheres from 1885-1992. 

The glass plates in the Fleming Collection were individually selected from over 550,000 plates to acknowledge their historic significance to the work of the Women Computers and their value in representing the use of astronomical glass plate photography at the HCO. These plates document experimentation in early astrophotography, significant advancements in spectroscopic classification, sky surveys, and star counts that revealed previously unknown galaxies, nebulae, novae, and other celestial objects. Both the plates and jackets contain markings, figures, and notations made by Women Computers such as Williamina Fleming, Annie Jump Cannon, Henrietta Swan Leavitt, and Cecilia Payne-Gaposchkin, although hundreds of women scientists, assistants, family members, and volunteers also contributed invaluable work at the observatory, on expeditions, and at HCO affiliated stations in the southern hemisphere. 

Most of the glass plates remain housed in their historic jackets. Plates in modern archival jackets are marked with transcriptions of the original historic notations. The glass plate photographs were assigned an alphanumeric label by the observatory at the time of capturing the image. This labeling convention established various photographic series which typically represented observations from a single telescope. Some series, notably the “MB” series, consist of data from multiple telescopes. Telescopes were occasionally moved across observatories depending on observational goals.

Formats and types of work include but are not limited to: spectra, pole comparisons, isochromatic work, galaxy counts, sequences, variables, globular clusters, “Willem Luyten's ‘blink’ work”, eclipses, sun spots, and diffraction grating.

Examples of celestial objects noted or represented: Andromeda, Orion Nebula, Centaurus, meteors, Eros, comets, Belanowsky’s Nova, Pleiades, Triangulum, Saturn, Moon, Jupiter, Large Magellanic Cloud, Small Magellanic Cloud.

The collection also includes plates that represent examples of multiple exposure photography and special plate mending techniques.

Administrative/Biographical History: The glass plates in this collection were individually selected to acknowledge their historic significance to the work of the Women Astronomical Computers and their value in representing the use of astronomical glass plate photography at the Harvard College Observatory. The collection is named in honor of Williamina Fleming, the first Curator of Astronomical Photographs at Harvard College Observatory.

Williamina Paton Fleming (1857-1911) was born on May 15, 1857, in Dundee, Scotland. Fleming immigrated to America in 1878, taking a position as housekeeper for Edward C. Pickering, the Harvard College Observatory’s fourth director. Recognizing her intelligence, Pickering hired Fleming in 1881 to join the team of Computers studying and performing calculations on astronomical glass plate photographs. During her 30-year career at the observatory, Fleming would become one of the most highly recognized and honored woman astronomers of her time. Fleming was a member of both the Astronomical Society of America and the Astronomical Society of France. She was invited by the Congress of Astronomy and Astrophysics to participate at Chicago’s Columbian Exposition of 1893. Fleming was elected as an Honorary Fellow in Astronomy by Wellesley College, and in 1906, she became the first American woman elected as an honorary member of the British Royal Astronomical Society. Only months before her death, Fleming was presented with a gold medal for her discovery of new stars by the Astronomical Society of Mexico. Her discoveries number 310 variable stars, 10 novae, and 52 nebulae, including the infamous Horsehead Nebula photographed on glass plate B02312.

In addition to her astronomical research, Fleming was responsible for managing the Henry Draper Memorial, a program to systematically photograph, study, and describe stellar spectra. She also organized the regular publication of the Annals of the Harvard College Observatory. Until her death in 1911, she supervised and mentored the team of Women Astronomical Computers, a term applied to women astronomers, assistants, family members, and volunteers who worked at the HCO. She believed that these women, although often denied educational and professional equality, could contribute valuable skills that were needed in the field of astronomy.

Women Astronomical Computers at the Harvard College Observatory continued to actively catalog and study stars, galaxies, and stellar spectra until the 1950’s, leaving their mark on the glass plates along the way.  Although women like Annie Jump Cannon, Henrietta Swan Leavitt and Cecelia Payne-Gaposchkin gained wide notoriety for their research and discoveries, most of the Computers were anonymous or uncredited assistants. In 2016, Lindsay Smith Zrull, Curator of Astronomical Photographs, began a project to reveal the identity of these women by studying names and initials in observation logbooks, notebooks, and notations on jacket sleeves. This research has identified 216 women who worked, volunteered, or actively researched at the Harvard College Observatory. Thus, the Fleming Collection of astronomical glass plate photographs is an invaluable record of the work process of hundreds of women astronomers in the late-19th and 20th centuries.  

Harvard College Observatory was founded in 1839, the same year Louis Daguerre invented the daguerreotype. Astronomers immediately saw the usefulness of the new technology to their observation work and experimentation in astrophotography became a priority at the HCO. By the 1870s, commercially produced gelatin photographic plates were introduced and celestial photography revolutionized the field of astronomy. “Dry” plates simplified the photographic process and allowed for shorter exposure times with more light sensitive emulsions that produced sharper imagery of the night sky. Under the direction of Edward C. Pickering, and with funding from philanthropist Anna Palmer Draper, the HCO began systematic surveys of the sky on spectral and direct image glass plate photographs. During this time the collection grows to over 100,000 glass plates and Women Computers are consistently employed to analyze and care for the collection.

Today, the HCO’s collection of astronomical glass plate photographs includes 550,000 images covering both the northern and southern hemispheres. This collection comprises over a century of irreplaceable scientific observations and represents the first full image of the visible Universe. Harvard College Observatory achieved this unique aspect of its collection by establishing foreign observatories south of the equator in locations like Peru, South Africa, and Jamaica. Current scholarship is examining problematic aspects of Harvard’s presence in these locations, including exploitative labor practices, racism, and land disputes. Alex McGrath’s 2019 master’s thesis, “You Take Our Stars: Harvard Astronomers in Peru, 1889-1900,” explores Harvard’s operations in the Peruvian Andes in more detail.  

All materials have been housed at the Harvard College Observatory since their creation. Glass plate photographs that originated at Harvard’s numerous foreign and domestic observatories were shipped to the Cambridge observatory and have been housed there since delivery.

Administrative Note on Historic Markings: For over a century, the astronomical photographic glass plates functioned as scientific records and living documents that were often handled by multiple researchers at the HCO. The glass plates are known to have been cleaned of markings and re-used for different research purposes over time. A plate’s historical jacket may indicate an individual used a glass plate in their research but this does not necessarily correspond to the individual(s) responsible for making the markings that have been preserved on the glass.

Since 2004, the HCO’s Digital Access to a Sky Century @ Harvard (DASCH) project has endeavored to digitize the majority of the Observatory’s glass plate negatives to produce full photometry results for the entire sky. As a matter of procedure, plates selected for DASCH were first photographed and then cleaned of their historic markings. However, there are known instances where plates were cleaned and prepared for scanning before being photographed. A plate without markings does not necessarily indicate that the plate was historically free of markings.

Current Arrangement and Description: This finding aid is arranged into one series chronologically by the photograph’s plate number. The collection has been processed using the minimum level of description at the item level. Each item represents one glass plate photograph. 


  • Astronomy -- 19th century.
  • Astronomy -- 20th century.
  • Fleming, Williamina Paton Stevens, 1857-1911
  • Glass plate negatives
  • Harvard College Observatory (Cambridge, MA)
  • Harvard University -- Astronomy.
  • Women astronomers -- History.


Cannon, A. J. (1911). Williamina Paton Fleming. Science, Vol. 33(861), 987–988.

Smith Zrull, L. (2021). Women in Glass: Women at the Harvard Observatory during the Era of Astronomical Glass Plate Photography, 1875–1975. Journal for the History of Astronomy, Vol. 52(2), 115–146. DOI: 10.1177/00218286211000470 

Wolbach Library. Glass Plate Collection Timeline. Retrieved August 17, 2022, from

Wolbach Library. Women at the Harvard College Observatory: Williamina Fleming. Retrieved August 17, 2022, from