Lightning has knocked out the first large telescope ever built on Mauna Kea, and engineers are working to bring it back online.

The University of Hawaii’s 2.2-meter telescope has been out since the weekend of June 4-5, when tens of thousands of lightning flashes were recorded around the state.

Colin Aspin, the telescope’s director, said Tuesday he’s not sure whether the problem was caused by a direct lightning strike or a strike on Saddle Road that affected power going to the mountain. None of the other dozen telescopes on the volcano appear to have suffered similar problems, indicating a direct strike might be the source.

When operators tried to open the telescope after the weather cleared, they couldn’t get its electrical systems to work. Once they fixed that, they discovered it moved in the wrong direction, pointing north, for example, when operators had told it to point west.

The 41-year-old telescope is smaller than its more famous neighbors, including the twin Keck telescopes, which have mirrors measuring 10 meters — about 32 feet — in diameter. But the pioneering machine was the first to demonstrate that Mauna Kea has some of the world’s best conditions for observing the skies.

In the early 1990s, astronomers used it to discover the existence of the Kuiper Belt, a region

beyond Neptune that is home to large numbers of asteroid-size bodies. Today, Pluto is commonly regarded as the largest known Kuiper Belt object, not as the ninth planet.

Aspin said repairs could have it back up within a day.

Engineers believe they’ve traced the problem to devices called opto-isolators that protect the telescope against electrical system surges. If they’re right, the telescope could be operational again soon.

The repairs haven’t been that financially costly so far, about $5,000 to $10,000, Aspin said. But they have required a lot of time and effort, including having an expert engineer fly in from Maui to help.

The telescope is primarily used by University of Hawaii graduate students and faculty, who have been looking forward to being able to use it again soon.

“They’re waiting patiently to get back on sky,” Aspin said.

The islands have had an unusual number of thunderstorms recently.

Robert Ballard, science and operations officer at the National Weather Service in Honolulu, said observers generally record about seven thunderstorm days at Honolulu Airport in a typical year, but they reported 28 between Nov. 1 and June 1.

“So we’re more than four times normal for a year, and we haven’t even gone the whole year yet,” Ballard said.