Keck spectrometer has astronomers eager

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Researchers will likely be able to begin using it in August, with the first findings being published three to four months later.

BY ERIN MILLER

WEST HAWAII TODAY

emiller@westhawaiitoday.com

A new instrument has astronomers around the world asking for a chance to get some sky viewing time at the Keck Observatory, Director Taft Armandroff said.

“They are so eager to get (access to) it, people are, in effect, busting down the doors to get access,” Armandroff said Friday.

The new instrument, a multiobject spectrometer for infrared exploration, or MOSFIRE for short, is a near-infrared spectrometer, 6 feet in diameter, about 12 feet long and weighing about 4,500 pounds. It arrived on Mauna Kea’s summit Thursday, after being shipped from California to Hilo.

MOSFIRE was seven years in the making. Ian McLean, principal investigator for the instrument at the University of California, Los Angeles, said getting it designed and built was a challenge.

Several things set MOSFIRE apart from other multiobject spectrometers. To observe infrared light, McLean said, the instrument’s interior will be a vacuum cooled to cryogenic temperatures. That means the mechanisms inside must also be cooled to those levels. Typical multiobject spectrometers focus on one object at a time, using a mask with slits cut just where that object appears, allowing in light from that object and no others.

“You could easily spend two or three hours on that one target,” McLean said. “It’s not efficient. You would like to do many galaxies or stars at one time.”

To look at different objects, astronomers have historically needed different masks. But to get those masks inside MOSFIRE would have required cooling each one before inserting it into the instrument. What sets MOSFIRE aside is 46 sets of small metal bars that can be remotely, robotically controlled.

“We make the little slits in the mask by having two metal bars approach each other to make a tiny gap,” McLean said.

That means astronomers may observe 46 objects at the same time.

Armandroff said Keck employees will take several weeks to hook up the instrument, then begin testing it.

“It will see its first light in April,” he added.

Researchers will likely be able to begin using it in August, with the first findings being published three to four months later.