New Galaxy-hunting Sky Camera Sees Redder Better

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Berkeley Lab supplied the charge-coupled devices (CCDs) that capture light and the readout system that translates the light into images, and Yale was responsible for new mechanical components and software. David Rabinowitz at Yale oversaw the software development, working closely with NOAO astronomers and engineers.

Mosaic-3 is equipped with four CCDs, each measuring about 6 square inches and containing 16 megapixels. Each pixel in the CCDs is about 100 times larger in area than a pixel in an iPhone 6 camera sensor, and each Mosaic-3 CCD is about 50 times larger in area than the iPhone 6 camera sensor.

“It’s really the light-gathering power that matters,” said Armin Karcher, a Berkeley Lab design engineer who built a compact, flexible readout system for the camera.

The large pixel size and overall CCD size are key in gathering light, and the 0.5-millimeter thickness of the CCDs helps the CCDs see deeper into the infrared wavelengths.

Steve Holland, an engineer at Berkeley Lab who invented these red-sensitive CCDs, said he was already engaged in the design of similar CCDs for the DESI project when Mosaic-3 launched. “It was serendipitous,” he said.

Christopher Bebek, who manages Berkeley Lab’s CCD group and served as the lab’s liaison on the Mosaic-3 project, added, “This was like a dress rehearsal for detectors and electronics for DESI.” An updated CCD design is now in production for DESI, which will require 20 of these CCDs for its spectrograph system.

The Mosaic-3 instrument upgrade was funded by the U.S. Department of Energy Office of Science through the DESI project, and by NOAO.  The DESI project is managed by the Lawrence Berkeley National Laboratory.

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