CHICAGO (AP) — Chicago’s renowned Field Museum, long a major center of global scientific research, is offering early retirement to more than half its curators as part of a wide-ranging effort to reduce debt and refocus the mission of one of the city’s top cultural attractions.

The natural history museum has offered the incentive — immediate retirement or a phased-in retirement over two to three years — to 16 of 27 curators, spokeswoman Nancy O’Shea said Thursday. Those eligible are 55 or older and have at least 10 years on the job. The must decide by May 10 if they’ll accept the offer, O’Shea said.