Observatory tests spectrometer

Stephens Media

A new instrument at W.M. Keck Observatory saw first light this week.

Astronomers aimed the Multi-Object Spectrometer for Infra-Red Exploration, or MOSFIRE for short, at some well-studied parts of the night sky, capturing several images as part of the instrument’s calibration phase.

“The idea was to choose targets that are well-known, relatively bright and easy, to prove it does what we expect,” principal investigator for the instrument Ian McLean said Friday. “In the future, once we’re fully calibrated, we can do things where we don’t know what to expect.”

McLean said he felt both relief and excitement after getting the first images. Relief, he said, because MOSFIRE is working like it’s supposed to. The excitement stems from the possibilities now available to astronomers to collect new data and make new discoveries with MOSFIRE.

The instrument arrived at the observatory on Mauna Kea in February. Engineers and scientists spent seven years designing and building the machine, which will allow astronomers to look at up to 46 objects at the same time. The instrument uses sliding bars to block or allow light from different objects. The bars are remotely controlled and kept cryogenically cooled to about -243 F inside a vacuum. Keeping the instruments so cold prevents infrared light from the ground, the telescope and MOSFIRE from interfering with image detection.

MOSFIRE creates images by gathering “spectra, which contain chemical signatures in the light of everything from stars to galaxies, at near-infrared wavelengths,” Keck officials said in a release about MOSFIRE’s first use. “Infrared is light, which is beyond red in a rainbow — just beyond what human eyes can detect. Observing in the infrared allows researchers to penetrate cosmic dust clouds and see objects that are otherwise invisible, like the stars circling the supermassive black hole at the center of the Milky Way. It also allows for the study of the most distant objects, the light of which has been stretched beyond the red end of the spectrum by the expansion of the universe.”

Scientists will use MOSFIRE to collect data on the universe from when it was a half-billion to a billion years old, the time when most galaxies were formed.