Professor emeritus of astronomy Harold Francis Weaver dies at 99

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UC Berkeley professor emeritus of astronomy Harold Francis Weaver and renowned radio astronomer died in his home April 26 at the age of 99.

Weaver, whose death was publicly announced by the campus Wednesday, was a longtime member of the campus community. He obtained both his bachelor’s and doctorate degrees from UC Berkeley and worked on-campus for decades afterwards.

Among Weaver’s biggest accomplishments, he discovered the existence of naturally occurring microwave lasers, also known as masers, in outer space. This achievement was made possible by the Radio Astronomy Lab, which Weaver co-founded in 1958 after years of proposal writing and searching for funding.

Weaver explained in an interview held with Ohio University astronomy professor Joseph Shields in 1991 that American research into radio astronomy was in a “rather weak state” in the 1950s. When Harvard University’s leading researcher in the field left for a position in Australia, Weaver said he saw an opportunity for UC Berkeley to fill the void and bring American radio astronomy up to speed.

In 1962, the lab dedicated its first two telescopes at Hat Creek Observatory in Northern California. Using the larger of the two, an 85-foot dish among the largest ever built at the time, Weaver and his colleagues detected their historic maser. While originally attributed to a theoretical substance called “mysterium,” further research revealed that the emission came from an interstellar molecular cloud, thereby helping to prove the existence of molecules in the vacuum of outer space.

Over the course of his career, Weaver also published several dozen research papers, mentored graduate and undergraduate students of astronomy and developed a survey of interstellar atomic hydrogen that Leo Blitz, a fellow professor emeritus of astronomy and a former director of the Radio Astronomy Lab, described as the most important of its time.

Weaver was also known for being a friendly and welcoming presence to those around him.

“In his downtime, he was the nicest guy,” Blitz said. “(He was) very pleasant to talk to.”

In an email, campus astronomy professor Alex Filippenko noted Weaver’s contributions to the astronomy community beyond UC Berkeley, including shaping multiple societies that current members of the astronomy department belong to.

Filippenko also cited Campbell Hall as one of Weaver’s longest-lasting contributions to the campus, even if it is not one he was necessarily known for creating.

“The astronomy department at (the campus) is housed in the new Campbell Hall,” Filippenko said in an email. “But for most of the past 60 years it was in the original Campbell Hall, which Harold helped to design and name….so, all current members of our department owe him a debt of gratitude for being largely responsible for our campus home.”