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The Dark Energy Survey (DES) is a next generation optical survey aimed at understanding the accelerating expansion of the universe using four complementary methods: weak gravitational lensing, galaxy cluster counts, baryon acoustic oscillations, and Type Ia supernovae. To perform the 5000 sq-degree wide field and 30 sq-degree supernova surveys, the DES Collaboration built the Dark Energy Camera (DECam), a 3 square-degree, 570-Megapixel CCD camera that was installed at the prime focus of the Blanco 4-meter telescope at the Cerro Tololo Inter-American Observatory (CTIO). DES started its first observing season on August 31, 2013 and observed for 105 nights through mid-February 2014. This paper describes DES “Year 1” (Y1), the strategy and goals for the first year's data, provides an outline of the operations procedures, lists the efficiency of survey operations and the causes of lost observing time, provides details about the quality of the first year's data, and hints at the “Year 2” plan and outlook.

The Dark Energy Camera (DECam) is a new 520 Mega Pixel CCD camera with a 3 square degree field of view built for the Dark Energy Survey (DES). DECam is mounted at the prime focus of the Blanco 4-m telescope at the Cerro-Tololo International Observatory (CTIO). DES is a 5-year, high precision, multi-bandpass, photometric survey of 5000 square degrees of the southern sky that started August 2013. In this paper we briefly review SISPI, the data acquisition and control system of the Dark Energy Camera and follow with a discussion of our experience with the system and the lessons learned after one year of survey operations.

The Dark Energy Camera and its cooling system has been shipped to Cerro Tololo Inter-American Observatory in Chile for installation onto the Blanco 4m telescope. Along with the camera, the cooling system has been installed in the Coude room at the Blanco Telescope. Final installation of the cooling system and operations on the telescope is planned for the middle of 2012. Initial commissioning experiences and cooling system performance is described.

The Dark Energy Survey Camera (DECam) will be comprised of a mosaic of 74 charge-coupled devices (CCDs). The Dark Energy Survey (DES) science goals set stringent technical requirements for the CCDs. The CCDs are provided by LBNL with valuable cold probe data at 233 K, providing an indication of which CCDs are more likely to pass. After comprehensive testing at 173 K, about half of these qualify as science grade. Testing this large number of CCDs to determine which best meet the DES requirements is a very time-consuming task. We have developed a multistage testing program to automatically collect and analyze CCD test data. The test results are reviewed to select those CCDs that best meet the technical specifications for charge transfer efficiency, linearity, full well capacity, quantum efficiency, noise, dark current, cross talk, diffusion, and cosmetics.

Fully depleted, back-illuminated, p-channel CCDs developed at Lawrence Berkeley National Laboratory exhibit high quantum efficiency in the near-infrared (700-1050nm), low fringing effects, low lateral charge diffusion (and hence small, well-controlled point spread function), and high radiation tolerance. Building on previous efforts, we have developed techniques and hardware that have produced space-qualified 4-side abuttable, high-precision detector packages for 10.5μm pixel, 3.5k x 3.5k p-channel LBNL CCDs. These packages are built around a silicon carbide mounting pedestal, providing excellent rigidity, thermal stability, and heat transfer. Precision fixturing produces packages with detector surface flatness better than 10μm P-V. These packages with active areas of 36.8mm square may be packed on a detector pitch as small as 44mm. LBNL-developed Front End Electronics (FEE) packages can mount directly to the detector packages within the same footprint and detector pitch. This combination, along with identically interfaced NIR detector/FEE packages offers excellent opportunities for high density, high pixel count focal planes for space-based, ground-based, and airborne astronomy.

The Dark Energy Camera (DECam) is the new wide field prime-focus imager for the Blanco 4m telescope at CTIO. This instrument is a 3 sq. deg. camera with a 45 cm diameter focal plane consisting of 62 2k × 4k CCDs and 12 2k × 2k CCDs and was developed for the Dark Energy Survey that will start operations at CTIO in 2011. The DECam CCD array is inside the imager vessel. The focal plate is cooled using a closed loop liquid nitrogen system. As part of the development of the mechanical and cooling design, a full scale prototype imager vessel has been constructed and is now being used for Multi-CCD readout tests. The cryogenic cooling system and thermal controls are described along with cooling results from the prototype camera. The cooling system layout on the Blanco telescope in Chile is described.

The Dark Energy Camera is an wide field imager currently under construction for the Dark Energy Survey. This instrument will use fully depleted 250 μm thick CCD detectors selected for their higher quantum efficiency in the near infrared with respect to thinner devices. The detectors were developed by LBNL using high resistivity Si substrate. The full set of scientific detectors needed for DECam has now been fabricated, packaged and tested. We present here the results of the testing and characterization for these devices and compare these results with the technical requirements for the Dark Energy Survey.

DECam, camera for the Dark Energy Survey (DES), is undergoing general design and component testing. For an overview see DePoy, et al in these proceedings. For a description of the imager, see Cease, et al in these proceedings. The CCD instrument will be mounted at the prime focus of the CTIO Blanco 4m telescope. The instrument temperature will be 173K with a heat load of 113W. In similar applications, cooling CCD instruments at the prime focus has been accomplished by three general methods. Liquid nitrogen reservoirs have been constructed to operate in any orientation, pulse tube cryocoolers have been used when tilt angles are limited and Joule-Thompson or Stirling cryocoolers have been used with smaller heat loads. Gifford-MacMahon cooling has been used at the Cassegrain but not at the prime focus. For DES, the combined requirements of high heat load, temperature stability, low vibration, operation in any orientation, liquid nitrogen cost and limited space available led to the design of a pumped, closed loop, circulating nitrogen system. At zenith the instrument will be twelve meters above the pump/cryocooler station. This cooling system expected to have a 10,000 hour maintenance interval. This paper will describe the engineering basis including the thermal model, unbalanced forces, cooldown time, the single and two-phase flow model.

We describe the Dark Energy Camera (DECam), which will be the primary instrument used in the Dark Energy Survey. DECam will be a 3 sq. deg. mosaic camera mounted at the prime focus of the Blanco 4m telescope at the Cerro-Tololo International Observatory (CTIO). DECam includes a large mosaic CCD focal plane, a five element optical corrector, five filters (g,r,i,z,Y), and the associated infrastructure for operation in the prime focus cage. The focal plane consists of 62 2K x 4K CCD modules (0.27"/pixel) arranged in a hexagon inscribed within the roughly 2.2 degree diameter field of view. The CCDs will be 250 micron thick fully-depleted CCDs that have been developed at the Lawrence Berkeley National Laboratory (LBNL). Production of the CCDs and fabrication of the optics, mechanical structure, mechanisms, and control system for DECam are underway; delivery of the instrument to CTIO is scheduled for 2010.

The Dark Energy Survey is planning to use a 3 sq. deg. camera that houses a {approx} 0.5m diameter focal plane of 62 2kx4k CCDs. The camera vessel including the optical window cell, focal plate, focal plate mounts, cooling system and thermal controls is described. As part of the development of the mechanical and cooling design, a full scale prototype camera vessel has been constructed and is now being used for multi-CCD readout tests. Results from this prototype camera are described.

A description of the plans and infrastructure developed for CCD testing and characterization for the DES focal plane detectors is presented. Examples of the results obtained are shown and discussed in the context of the device requirements for the survey instrument.