HONOLULU — Officials from a Big Island astronomical observatory say an oil leak was discovered in the hydraulic system supporting one of its telescopes.

Officials from the W.M. Keck Observatory notified the state Department of Health of the leak from the Keck I telescope on Monday, even though it was first detected on April 19, the Honolulu Star-Advertiser reported .

The observatory was slow to launch a full investigation, Hilton Lewis, the observatory's director, said in a statement.

"We are now giving this investigation the full attention it requires as the top priority for the observatory," Lewis said.

He added that he regrets the delay and takes full responsibility.

The Keck I telescope's hydraulic system has a total capacity of 550 gallons (2,082 liters) of oil and is topped off with fresh oil as needed, said Richard Matsuda, the observatory's chief of operations.

It's unclear how much oil was leaked, but officials have found no obvious dripping or pouring and say the leak appears to be small.

Technicians also inspected the Keck I's twin telescope, Keck II, and found no oil seeping on the Keck II's pier wall.

The Keck Observatory is located near the summit of Mauna Kea.

It was damaged in the large 6.9 earthquake that hit the Big Island on May 4, the day after Kilauea volcano started its latest East Rift Zone eruption.

The quake knocked the Keck I's mechanical bearing system out of operation for four days. The system keeps the telescope centered as it rotates.

The Keck II was not damaged in the quake.

It's unknown whether the earthquake exacerbated the oil leak.