Janet Akyüz Mattei was a Turkish-origin astronomer known for her work on variable stars and served as director of the American Association of Variable Star Observers (AAVSO) from 1973 to 2004. She pursued her education in both Türkiye and the United States and conducted various studies in the collection and evaluation of observational data and the inclusion of amateur astronomers in the scientific process.

Janet Hanula Akyüz was born on 2 January 1943 in Bodrum, Türkiye. She completed her secondary education at the American College of İzmir. In 1962 she was admitted to Brandeis University under the Vienna International Scholarship Program and earned her bachelor’s degree in general science (physics) in 1965. Upon returning to Türkiye she taught mathematics and physics at secondary schools. She completed her master’s studies at Ege University in 1970.

In the summer of 1968 she participated in a summer program at the Maria Mitchell Observatory under the direction of Dorrit Hoffleit, where she became acquainted with variable stars. There she met the AAVSO and her future husband Michael Mattei. In 1972 she earned her second master’s degree from the University of Virginia with a thesis on T-Tauri stars. In 1982 she received her doctorate from Ege University with a thesis on dwarf nova analysis based on AAVSO data.

In 1972 she began working at AAVSO as an assistant. In 1973, following the retirement of Margaret Mayall, she was appointed director of AAVSO. During her tenure the organization evolved from recording 150,000 observations annually to processing 450,000 observational records electronically each year. The institution’s data infrastructure was modernized and the AAVSO International Database was established. Real-time data sharing with observatories was implemented. With the support of Clinton B. Ford the organization moved into its own building.

During this period an early warning system was developed to monitor sudden outbursts of cataclysmic variable stars. Special observation programs were also initiated to detect optical afterglows following gamma-ray bursts. AAVSO data were used in observations of the star SS Cyg made with the HEAO-1 X-ray telescope; subsequently similar studies were conducted for approximately 600 stars.

She led scientific projects based on variable stars for secondary school students, emphasizing the scientific method and mathematical analysis. She mentored over 150 student projects. She contributed to the development of a curriculum for learning through variable star observations within AAVSO. She participated in United Nations international programs aimed at promoting astronomy education.

In her role at AAVSO she managed the systematic collection and conversion of individual observers’ work into scientific data. Hundreds of thousands of star observations made by amateur astronomers were processed into the AAVSO database. These data served as reference for numerous space and ground-based telescopes.

Mattei held active positions in the following organizations and committees:

• International Astronomical Union – Commission on Variable Stars
• NASA Astrophysics Review Panel
• NASA Astrophysics Division Scientific and Operational Working Group
• Astronomical Society of the Pacific Bylaws Committee

She received the following awards from various institutions:

• Centenary Medal of the French Astronomical Society (1987)
• George Van Biesbrock Prize of the American Astronomical Society (1993)
• Leslie Peltier Award of the Astronomical Society of the Pacific (1993)
• Giovanni Battista Lacchini Prize of the Italian Association of Astronomy Enthusiasts (1995)
• Jackson-Gwilt Medal of the Royal Astronomical Society (1995)

Janet Akyüz Mattei died on 22 March 2004 in Boston from acute myeloid leukemia. In her honor the AAVSO Council established a research fellowship. Following her death, over 200 tributes were sent to the AAVSO website from around the world.