NEW YORK — A mural of constellations in the night sky adorned a third-floor ceiling at DeWitt Clinton High School for more than 75 years, one of thousands of artworks in New York City and around the country supported by New Deal programs to employ artists and beautify public spaces.

But Scorpio, Taurus and the rest are now hidden under bright blue paint, slathered on during a repair project, and preservationists say the painting-over of the mural “Constellations” by German-born artist Alfred Floegel was a travesty.

“That was an amazing act of vandalism that they had no right to do,” said Gray Brechin, the founder of a project called the Living New Deal that catalogs public works funded by the Franklin Delano Roosevelt administration.

The mural cover-up was first reported in the Daily News, which said it happened last November. Doug Cohen, a spokesman for the New York City Department of Education, said the mural was painted over during roof repairs at the 89-year-old Bronx school. He said officials are “exploring ways to restore this historic artwork.”

One art restorer said it would be possible, though expensive, to remove the blue paint from “Constellations.”

“I would think that it could be done not only safely, it could look perfect,” said Scott Haskins of Santa Barbara, California-based Fine Art Conservation Laboratories.

Haskins said “Constellations” is not the first historic school mural to be painted over.

“Every once in a while you get a dingbat principal that gets a roller out and tells maintenance to give it a fresh coat of paint,” he said. “I’ve seen it happen all over the country.”

There have been several cases of New Deal murals that were painted over and later restored.

Seven murals at New Mexico Highlands University depicting different fields of knowledge were covered with white paint sometime in the 1960s. They were restored in 2011 after the New Mexico New Deal Preservation Association hired an art conservator to uncover them.

The Cedar Rapids murals were painted over in the 1950s amid controversy over images depicting justice in what was then a federal courthouse. The murals were restored, then covered up again in the 1960s, then restored again between 2011 and 2013.

Brechin and others at the Living New Deal project say the loss of the DeWitt Clinton mural, whether temporary or permanent, shows how the legacy of the Works Progress Administration and other New Deal public art initiatives has been forgotten.

“It was a renaissance the likes of which we haven’t seen before or since,” said Brechin, a visiting scholar the University of California, Berkeley’s department of geography. “Roosevelt and Eleanor Roosevelt and the people around them believed that all Americans deserved the right to art.”

The Living New Deal database includes hundreds of murals at schools, post offices and other government buildings painted between 1934 and 1943, many illustrating scenes from U.S. or world history.

There are a number of New Deal murals at New York City public schools, where few people besides students and staff ever see them.