Four years after she declined a prestigious Mallinckrodt chair position unaccompanied by a tenured professorship, Professor of Astronomy Margaret J. Geller tendered her resignation from Harvard yesterday, effective July 1.

A Harvard faculty member for over 20 years, Geller released a public statement saying her resignation was prompted by "refusal by the University to make my appointment comparable with those of the men who hold Mallinckrodt chairs and subsequent actions and statements by representatives of the University."

According to Paine Professor of Practical Astronomy Jonathan E. Grindlay, informal rumors had been recently circulating in the department that Geller's resignation was imminent, and her teaching fellows had known for months that she would not return next year.

Geller, who won a MacArthur Fellowship, more commonly known as the "genius grant" in 1990 and was the first Harvard female professor elected to the National Academy of Sciences, was offered the unprecedented untenured chair due to a "personal issue," according to what Dean of the Faculty Jeremy R. Knowles said in 1999.

The eight male science professors who hold the chair Geller was offered are all tenured.

Geller, who has criticized the University for gender discrimination in its promotion practices, stopped speaking on behalf of the University and attending faculty meetings after she was offered the untenured chair. Grindlay said that Geller's involvement in the Astronomy Department had declined since she was offered the untenured position.

"The last couple of years, she hasn't been playing a very active role," he said.

Geller will continue in her capacity directing the telescope data center at the Center for Astrophysics, a joint Harvard-Smithsonian venture administered by the Smithsonian, although Geller does not hold the title of director as her male predecessors did.

According to Grindlay, she did not suggest to department members that she would seek another academic faculty position.

-Staff writer Daniel K. Rosenheck can be reached at rosenhec@fas.harvard.edu.