The Dark Energy Camera is a new imager with a 2°. 2 diameter field of view mounted at the prime focus of the Victor M. Blanco 4m telescope on Cerro Tololo near La Serena, Chile. The camera was designed and constructed by the Dark Energy Survey Collaborationand meets or exceeds the stringent requirements designed for the widefield and supernova surveys for which the collaboration uses it. The camera consists of a five-element optical corrector, seven filters, a shutter with a 60 cm aperture, and a charge-coupled device (CCD) focal plane of 250 μm thick fully depleted CCDs cooled inside a vacuum Dewar. The 570 megapixel focal plane comprises 62 2k × 4k CCDs for imaging and 12 2k × 2k CCDs for guiding and focus. The CCDs have 15 μm × 15 μm pixels with a plate scale of 0 263 pixel −1. A hexapod system provides state-of-the-art focus and alignment capability. The camera is read out in 20 s with 6-9 electronreadout noise. This paper provides a technical description of the cameraʼs engineering, construction, installation, and current status.

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Abslracl -An L-band total power receiver for use in a synthetic thinned array radiometer (STAR) is described. The total power architecture of a radiometer receiver requires special considerations to control gain fluctuations due to small temperature drifts. The STAR application requires consistent passband and stable phase between receiven. The design presented incorporates direct detection to eliminate distributed local oscillators for phase stability, distributed ceramic interference reject filters for passband consistency and temperature compensating atteuuatnrs for gain stability. The receiver is packaged in a unique "winged-hex'' shape to enable close packaging with the STAR antennas and to facilitate thermal management. The resulting low cost, compact receiver is made from COTS components.