1815- A Boston clock maker named William Cranch Bond is sent to Europe to study the Greenwich Observatory in preparation for a potential Harvard College Observatory (HCO). He predicts that the costs of building an observatory will be much higher than originally thought. Plans are put on hold for several years.

1835- Halley’s comet returns and sparks public interest in astronomy.

1839- Harvard Observatory is founded. Harvard President Josiah Quincy elects William Cranch Bond as the first director. They use Bond’s personal equipment until university instruments can be built.

1839- The daguerreotype is invented by Louis Daguerre. François Arago begins experimenting with the new technology for the study of astronomy. Before photography techniques were perfected, all observations were hand drawn.

1840- English-American scientist, Dr. John Draper, makes the first successful daguerreotype of the moon, with a 20 minute exposure (Daguerre had attempted this in early daguerreotype tests, but they’d failed). 

1843- Fundraising efforts to build a dome and a top of the line refracting telescope are initiated. It was to be the twin of the great telescope in the Poulkovo Observatory in Russia.

1843- John Draper takes solar spectrum daguerreotypes capturing the spectra of the sun. 

1844- Facility is built at new (current) observatory site.

1847- The glass lens for the telescope, The Great Refractor, is delivered from Europe. The telescope is installed on top of its base, known as the Sears Tower. The first observations include the Great Nebula in Andromeda and the Orion Nebula.

1846- Neptune is discovered, though it had been suspected for many years due to Uranus’s gravitational pattern.

1846- The first salaries for observers are paid thanks to funds raised by Boston citizens. Edward Bromfield Phillips wills $100,000 more in 1849, creating the Phillips Professorship of Astronomy which first went to William Cranch Bond.

1849- The Annals of the Astronomical Observatory of Harvard College begin publication.

1849- John Whipple takes a daguerreotype of the moon on Harvard’s Great Refractor. It won him a gold medal at the Crystal Palace exposition in London in 1851.

1851- Collodion (“wet”) plates are developed by Frederick Scott-Archer and Gustave Le Gray.

1850- The first Harvard daguerreotypes of stars are taken by Whipple. He also obtains the first known image of a double star (Castor) and the star Beta Lyrae.

1850s-70s- Scientists all around the world perfect daguerreotype and collodion photographs of eclipses, the sun and the moon.

1851- George Bond reports successful daguerreotypes of Jupiter taken with the Great Refractor. This may be the first image taken of a planet.

1854- The Cambridge Astronomical Society is founded.

1857- HCO observers begin experimenting with photographing stars on “wet” plates.

1857- A new control mechanism is installed in the Great Refractor, making it easier to guide for stellar photography, especially with the sensitive collodion plates. William Bond directs that more stellar photographs will be taken. 

1857- George Bond captures the first successful photograph of Saturn.

1859- George Phillips Bond, son of William Cranch Bond, becomes the second director. He struggles to keep the observatory functioning due to low funds during the Civil War. Harvard claims it can’t give more money because the observatory isn’t essential to the operation of the college. George Bond becomes obsessed with perfecting stellar photography throughout his time as director.

1866- Joseph Winlock becomes the third director of the Observatory, which is in debt to the university and in poor condition due to low funding. He installs gas, heat and water to the buildings after more income is secured.

1869-70- HCO takes photographs of solar eclipses.

1870s- The development of gelatin (“dry”) photographic plates makes celestial photography immensely easier and changes the game.

1870s- HCO takes several hundred solar photographs.

1872- Dr. Henry Draper, New York physician and son of John Draper, places a prism over photographic glass and takes the first truly successful stellar spectrum photograph of Vega, where characteristic lines are captured. This success sparks his lifelong interest in stellar photography. The earliest attempts at spectroscopy began in 1842, though they were never very successful.

c.1875- Harvard Observatory begins admitting women as staff. Before then, women, like Eliza Quincy, daughter of founder Josiah Quincy, were only given volunteer status as observers, though several women had applied to work as student assistants. The first Women Astronomical Computers hired are Rebecca T. Rogers, Rhoda G. Saunders and Anna Winlock. They are hired to assist William A. Rogers. Saunders remains at the observatory for 13 years.

1876- Edward C. Pickering is appointed as the fourth director of the Observatory, though he doen’t take on his duties until Feb. 1877. Professor Arthur Searle serves as acting director in the meantime. Pickering, with support from his wife Lizzie, begins hiring women computers on a regular basis and he remains the HCO director for nearly 40 years. The women are paid 25-30 cents an hour and work 6 days per week.

1879- Radcliffe College, Harvard’s sister school for women, is founded.

1879- Selina Cranch Bond, William Bond’s daughter and George Bond's younger sister, is hired as a computer. She works from home for many years due to poor health. When she’s in her 70s, her nieces and Pickering collborated to raise funds for her to retire with financial security, granting her the title Assistant Emerita.

1877-1919- Pickering works on raising funds for the Observatory. He studies stellar spectra, variable stars, novae, clusters, nebulae and comets until his death in 1919. He is most famous for hiring Harvard’s many female computers and for co-founding the Appalachian Mountain Club.

c. 1879- Pickering hires a Scottish housemaid, Williamina Fleming, to care for the observatory house, where the directors traditionally live. At the time, Fleming was pregnant and her husband had abandoned her.

1880- Draper takes first photograph made of a nebula (Orion). Though there were rumors of earlier images in Europe, none were confirmed.

1881- Impressed with Fleming’s intelligence, Pickering hires her as a part-time computer at the observatory. Nettie A. Farrar, one of the Women Astronomical Computers, trains her until Farrar leaves to get married in 1885. Fleming is soon charged with the management of the Women Astronomical Computers, the organization of the Henry Draper Memorial program and the publication of the Annals.  Fleming also develops the Henry Draper Catalogue of spectral classification with Pickering. She works at the observatory for over 30 years.

1882- Pickering orders ongoing photographic stellar investigations, creating the astronomical photographic plate collection.

1882- Dr. Draper dies and his widow, Anna (Palmer) Draper, tries to find an assistant to help her at her own Draper Observatory in Hastings, NY. She wants to finish her husband’s work on stellar spectroscopy, which he had planned to devote himself to full time.

1886- After Anna Draper fails to find someone to complete the work in her own observatory, she collaborates with Pickering and donates funds and equipment to the Harvard Observatory to support a department of  stellar spectroscopy. The studies in stellar spectra became known as the Henry Draper Memorial, in honor of her husband. Astronomical findings are published in the Draper Catalogue of Stellar Spectra. Anna Draper is largely responsible for funding the corps of women computers.

1886- Louisa Winlock, daughter of Joseph Winlock, is hired and joins her sister Anna, who is already a computer.

1888-1896- Antonia Maury niece of Henry Draper, is hired to study stellar spectra. Instead of following the Draper Catalogue system of classification, Maury develops her own system, which is much more detailed.

1889-1890- A small observatory station for Harvard observers is set up on the remote Wilson’s Peak (Mt. Wilson), California. Living conditions are rustic and it's difficult to send supplies. Despite good photos taken, land disputes and observer unhappiness with the conditions cause Pickering to shut down the station.

1889- Catherine Wolfe Bruce, a New York heiress and astronomy enthusiast, gives the observatory funds to build the Bruce refractor telescope, a 24-inch giant built in the style of Harvard's 8-inch Bache telescope. It was completed and installed in Boyden Station, Peru, in 1896.

1889- Solon Bailey lives in a rustic station on Mt. Harvard in Peru with his family and assistants. (He had wanted to name the mountain “Mt. Pickering,” but Edward Pickering suggested he didn’t deserve such an honor). Bailey’s wife, Ruth, assists in recording observations and shipping photographic plates back to Cambridge. Bailey travels with his brother, Marshall, to scout potential new locations in Peru.

1890- The first Draper Catalogue of Stellar Spectra is published through the Henry Draper Memorial. It lists the position, brightness and spectral type of 10,351 stars. Most of the classification were done by Williamina Fleming.

1890- After a large monetary gift from Uriah Boyden, the Boyden Station in Arequipa, Peru is established to watch the southern sky for Harvard. It’s much more accessible than Mt. Harvard had been. Pickering’s brother, William Pickering, along with his wife Anne and two children, is sent to Peru to set everything up but he spends far too much money on the land and construction of the station and house. The initiative is nearly recalled due to budgetary concerns. Spectra photographic work is seriously delayed and sporadic because William is more interested in studying planets than stars.

1892- Edward Emerson Barnard captures first photograph of a comet.

1893- Edward Pickering recalls William to Cambridge and replaces him with Solon Bailey as the new Arequipa station administrator. Reliable assistant staffing is a problem for the station and the Peruvian civil war makes conditions dangerous from 1893-1895.

1893- Bailey climbs nearby Mt. Misti and establishes a meteorological station for Harvard, making it the highest meteorological station in the world. Someone from the Arequipa station makes the hike once a month to check equipment and collect weather records. A local priest insists on holding High Mass at the summit to give his blessing to the station.

1894- Pickering tries to establish an observing station in Arizona Territory, believing its climate will be perfect for viewing Mars, but the plans fall apart.

1896- Annie Jump Cannon begins volunteering at the Observatory while taking graduate classes at Radcliffe. She is mostly deaf due to contracting scarlet fever after finishing college at Wellesley. Cannon is eventually hired as an official computer. She studies stellar spectra and upgrades Fleming’s stellar classification system. Additionally, she leads a team of computers in publishing nine volumes of the Henry Draper Catalogue between 1918-1924. She also creates the Harvard Catalogue of Variable Stars and the star classification sequence OBAFGKM (known by its mnemonic device: Oh Be A Fine Girl, Kiss Me).

1898- Bailey’s term at the Arequipa station expires and he turns it over to Dr. De Lisle Stewart, Royal H. Frost and W. B. Clymer. The work on the Mt. Misti meteorological station is manned by Juan E. Muniz.

1899- Williamina Fleming is appointed as the first Curator of Astronomical Photographs, making her the first woman to hold an official title at the observatory, and at Harvard University at large. She holds the post until she dies in 1911.

1903- Pickering compiles sets of 55 plates that form complete maps of the sky. He sells these sets to astronomers.

1906- Pickering orders a large scale effort to determine stellar magnitudes with the use of photography after 20 years of experimentation.

1907- Pickering announces his intention of creating a standard Polar sequence of stellar brightness (magnitude). Henrietta Swan Leavitt, who is partially deaf like Cannon, is hired as the leading computer on the project. Leavitt searches for variable stars in the Magellanic Clouds. Her most common method was through superposition, placing one negative atop another that was taken at a later date. By the time of her death in 1921, she discovers around 2,400 variable stars. She also develops a method for measuring celestial distances through periodic-luminosity relations.

1907- Margaret Harwood is hired as a computer. She would go on to be the first director of the Maria Mitchell Observatory on Nantucket.

1911- Pickering promotes Cannon as the second Curator of Astronomical Photographs though Harvard President Lowell refuses to allow her to be listed in the staff catalog. President Lowell admits he feels Fleming shouldn’t have been either. Cannon is, finally, recognized by the corporation and receives an official appointment in 1938.

1911-1924- Pickering sets up a station in Mandeville, Jamaica, administrated by his brother, William, who contributes to the funding. This station does little stellar photography and mostly focused on the solar system. After Harvard severs its ties with Mandeville in 1924, William and Anne stayed and kept the station in private operation until he died in 1938.

1914- Anna Draper dies and wills an additional $150,000 to her Henry Draper Memorial fund. The fund still supports the Curator of Astronomical Photographs position today.

1919- To date, forty women have worked in the observatory since 1875. (Read about their stories here)

1919- Edward Pickering dies and Solon Irving Bailey serves as acting director.

1920s- Henrietta Leavitt begins studying the “nebula” on the glass plates. It’s soon discovered that they’re actually individual galaxies.

1921- Harlow Shapley is chosen as the fifth director of the Observatory. His wife Martha Betz Shapley had entered the astronomy field after her marraige and specialized in calculating the orbits of eclipsing binary stars, among her other work.

1925- Cecelia Payne-Gaposchkin becomes the first person to earn a PhD in astronomy from Harvard, though, as a woman, her degree officially comes from Radcliffe. (Women were not admitted into Harvard until 1977, though they’d taken classes with the Harvard professors through Radcliffe for about a century.) The university creates the degree especially for Payne-Gaposchkin. In her PhD research, Payne-Gaposchkin discovers that the atmosphere of the sun is made mostly of hydrogen, in contrast to the popular view that the sun had the same composition as the Earth. Astronomer Otto Struve calls her work "undoubtedly the most brilliant PhD thesis ever written in astronomy." 

1926/7- Boyden Station in Arequipa, Peru moves to Mazelspoort, near Bloemfontein, South Africa. This move was overseen by, and the observatory eventually under the direction of, John Paraskevopolous. His wife Dorothy, had done computing work with the Observatory prior to her marriage.

1929- Edwin Hubble uses Henrietta Leavitt’s work on celestial distance to discover that the universe is expanding.

1932- Annie Cannon wins the Ellen Richards research prize for women distinguished in science. She gives the reward money to the American Astronomical Society to establish the Annie Jump Cannon Prize for women astronomers.

1938- Annie Cannon is finally recognized as the Curator of Astronomical Photographs by the Harvard Corporation. That same year she’s named the William Cranch Bond Astronomer at Harvard. She also becomes the first recipient of the Cecelia Payne Gaposchkin Award.

1940- Annie Jump Cannon retires. No new Curator of Astronomical Photographs is known to have been appointed until Martha Hazen in the 1960s. Cannon’s former assistant, Margaret Mayall Walton, completes the last of Cannon’s duties.

1945- Donald Menzel is appointed as the sixth director of the observatory.

1950s- Due to financial concerns, Director Donald Menzel halts the plate-taking operation for several years, a period known as the Menzel Gap. Plate collection resumes in the 1960s though staff numbers in the astronomical plate collection had dwindled.

1955- Menzel convinces the Smithsonian Astrophysical Observatory to relocate to Cambridge.

1956- Cecelia Payne-Gaposchkin becomes the first woman to be promoted to full professor within the Faculty of Arts and Sciences. She is later appointed the third chair of the Astronomy Department, making her the first woman to head a department at Harvard.

1960s- Martha Hazen is appointed as the new Curator of Astronomical Photographs and begins to organize the plates and data that had been largely neglected since the 1950s due to low staff and funding. The Menzel Gap ends around this time and more photographic plates are collected.

1973- The Smithsonian Astrophysical Observatory and the Harvard College Observatory combine into one entity, The Harvard-Smithsonian Center for Astrophysics.

1977- Women students are admitted to Harvard University.

1992- The last of the astronomical photographic plates are collected and the program is shut down. Advanced technology makes the collection of glass plate negatives obsolete.

1995- Martha Hazen retires and appoints her assistant, Alison Doane, as the new Curator of Astronomical Photographs. She is the only staff member left in the archive, excepting occasional part-time helpers.

2003- Robert Treat Paine Professor of Practical Astronomy Jonathan (Josh) Grindlay begins organizing DASCH (Digitizing A Sky Century at Harvard), a project to digitize more than 500,000 of the astronomical plates. More staff are hired. Custom scanner and software are built and the scanning pipeline begins in 2009.

2017- After Alison Doane retires, Lindsay Smith-Zrull is appointed  as the new Curator of Astronomical Photographs and oversees the work of part-time helpers working on DASCH

2022- The Glass Plate Collection is formally incorporated into the John G. Wolbach Library. Daina Bouquin, Head Librarian of Wolbach Library, becomes the senior administrator of the Collection, its associated staff, and the DASCH project. Wolbach's Assistant Head Librarian, Katie Frey, begins directly supporting the technical execution of DASCH. Sarah Lavallee is appointed Acting Curator of Astronomical Photograph upon Lindsay Smith-Zrull's departure. Sarah subsequently left the Observatory in July 2022.