Image: This test image of the Andromeda galaxy was captured using DESI. The circles indicate 5,000 “measuring points” of the instrument: a spectrum was recorded for each of these positions. (DESI cooperation)
On May 17th, the new DESI spectroscopy instrument was commissioned at Kitt Peak in Arizona (USA). Over the next five years, astronomers will use it to capture light from tens of millions of galaxies and other cosmic objects to create a detailed, three-dimensional map of the universe.
DESI breaks light from observed objects into their component colors. In this way information about their chemical composition, distances and velocities are obtained. This data will be used to better understand the mysterious dark energy that appears to be responsible for the accelerating expansion of the universe. Hence, “DESI” stands for dark energy spectroscopic instrument.
DESI’s official mandate comes after a four-month testing phase. Four million spectra have actually been recorded in this short period – more than all previous spectral surveys combined.
DESI is linked to Mayall’s nearly fifty-year-old four-meter telescope in Kitt Peak. The device is equipped with optics that expand the field of view of this telescope, and 5000 glass fibers controlled by the robot through which the spectra of the largest number of objects can be collected at once. In fact, the telescope looks at five thousand objects at the same time.
