HILO, Hawai'i — Repairs of the damage caused by the Oct. 15 earthquakes wrapped up last week for the Subaru telescope and were to be completed yesterday for Gemini North, but engineers at the powerful W.M. Keck Observatory continued to puzzle over new problems that are interfering with operations.

The three observatories on Mauna Kea have some of the most powerful optical telescopes in the world, and the magnitude 6.7 and 6.0 earthquakes last month damaged sensitive equipment and shook precision aiming devices out of alignment.

The twin telescopes at the Keck Observatory have been able to work in tandem since Nov. 4 and use their interferometer, a tool that combines the light gathered by the two telescopes to enhance images and make the telescopes much more powerful.

However, the telescopes are still unable to adjust their aim at their normal speed, and still cannot be pointed at some parts of the night sky, said Laura Kinoshita, public information officer for Keck.

Kinoshita said astronomers are able to use the observatory to gather data for their research, but "may not be able to view all of their desired targets."

New consultants have been hired to help with repairs, and Kinoshita said a laser study is planned of the systems that support the 300-ton telescopes.

The telescopes rest on four legs that glide over a thin layer of oil on a metal track, and scientists hope the laser survey of the system will reveal why Keck I in particular is not functioning as it should, she said.

At Gemini, astronomers planned to test the telescope this weekend after replacing a damaged mount on Gemini's secondary mirror, which is used to correct for image distortions caused by turbulence in the Earth's atmosphere.

Engineering tests were planned for last night, followed by additional instrument testing.

"In light of the fact that other Mauna Kea telescopes have run into technical glitches once back on the sky, we will not be surprised if we find similar small problems once systems are fully exercised," Gemini officials said in a statement posted on the observatory's Web site.

At Subaru, scientists announced on Monday that the observatory "is now tracking celestial objects at its pre-earthquake performance level." Testing of other equipment was completed by Wednesday, according to the observatory.

Reach Kevin Dayton at kdayton@honoluluadvertiser.com.