NEW YORK — A wristwatch believed to have been used to declare the time of President John F. Kennedy’s death is being auctioned in New York City.

The 18-carat Patek Philippe timepiece is estimated to bring up to $150,000 at Christie’s on Dec. 17. The watch was made in 1948 and purchased for Dr. Kemp Clark by his mother in Switzerland a year later for $750.

Clark was one of several attending physicians at Parkland Memorial Hospital in Dallas on Nov. 22, 1963, when the president entered the emergency room. He pronounced Kennedy dead at 1 p.m. by referring to the watch, according to his family, and signed the death certificate. “There is endless debate among historians on the actual time of death and there was most likely also a clock in the ER,” said John Reardon, Christie’s international co-head of watches. “However, the family and historians agree to these facts: the watch was on his wrist that day and he called the time of death and signed the death certificate.”

Friday is the 50th anniversary of Kennedy’s death.

Clark, who died in 2007, created the neurosurgery service at Southwestern Medical School and Parkland Memorial Hospital in 1956 and the neurosurgery residency program in 1962.