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The Dark Energy Camera is a new imager with a 2.2-degree diameter field of view mounted at the prime focus of the Victor M. Blanco 4-meter 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 wide-field 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 CCD focal plane of 250 micron thick fully-depleted CCDs cooled inside a vacuum Dewar. The 570 Mpixel focal plane comprises 62 2kx4k CCDs for imaging and 12 2kx2k CCDs for guiding and focus. The CCDs have 15 microns x15 microns pixels with a plate scale of 0.263 arc sec per pixel. A hexapod system provides state-of-the-art focus and alignment capability. The camera is read out in 20 seconds with 6-9 electrons readout noise. This paper provides a technical description of the camera's engineering, construction, installation, and current status., Comment: submitted to AJ Corresponding Authors H. T. Diehl (diehl@fnal.gov)

Results of a survey of instrumentation and detector systems, either currently deployed or planned for use at telescopes larger than 3.5 m, in ground based observatories world-wide, are presented. This survey revealed a number of instrumentation design trends at optical, near, and mid-infrared wavelengths. Some of the most prominent trends include the development of vastly larger optical detector systems (> 109 pixels) than anything built to date, and the frequent use of mosaics of near-infrared detectors – something that was quite rare only a decade ago in astronomy. Some future science applications for detectors are then explored, in an attempt to build a bridge between current detectors and what will be needed to support the research ambitions of astronomers in the future.

The CTIO V. M. Blanco 4-m telescope is to be the host facility for the Dark Energy Survey (DES), a large area optical survey intended to measure the dark energy equation of state parameter, w. The survey is expected to use ~30% of the telescope time over 5 years and use a new 520 megapixel CCD prime focus imaging system: the Dark Energy Camera (DECam). The Blanco telescope will also be the southern hemisphere platform for NEWFIRM, a large area infrared imager currently being commissioned at the Mayall Telescope at KPNO. As part of its normal cycle of continuing upgrades and in preparation for the arrival of these new instruments, the Blanco telescope control system (TCS) will be upgraded to provide a modern platform for observations and maximize the efficiency of survey operations. The upgraded TCS will be based on that used at the SOAR telescope and will be a prototype of the TCS to be used by LSST. It will be optimized for programmed and queued survey observations, will provide extended real-time telemetry of site and facility characteristics, and will incorporate a distributed observer interface allowing for on- and off-site observations and real time quality control. Hardware modifications will include the use of absolute tape encoders and a modern servo control and power driver systems.

The Dark Energy Survey Camera (DECam), when completed, is going to have one of the largest existing focal planes, equipped with more than 70 CCDs. Due to the large number of CCDs and the tight space on the camera, the DECam electronics group has developed new compact front-end electronics capable of flexibly and rapidly reading out all the focal plane CCDs. The system is based on the existing MONSOON Image Acquisition System designed by the National Optical Astronomy Observatory (NOAO), and it is currently being used for testing and characterization of CCDs. Boards for the new readout are being developed in USA and Spain, with the first prototypes already produced and tested. The next version with some improvements will be tested during 2008 and the system will be ready for production at the beginning of 2009. Custom MONSOON boards and the electronics path will be described.

We briefly describe the SOAR Optical Imager (SOI), the first light instrument for the 4.1m SOuthern Astronomical Research (SOAR) telescope now being commissioned on Cerro Pachon in the mountains of northern Chile. The SOI has a mini-mosaic of 2 2kx4k CCDs at its focal plane, a focal reducer camera, two filter cartridges, and a linear ADC. The instrument was designed to produce precision photometry and to fully exploit the expected superb image quality of the SOAR telescope over a 5.5x5.5 arcmin2 field with high throughput down to the atmospheric cut-off, and close reproduction of photometric pass-bands throughout 310-1050 nm. During early engineering runs in April 2004, we used the SOI to take images as part of the test program for the actively controlled primary mirror of the SOAR telescope, one of which we show in this paper. Taken just three months after the arrival of the optics in Chile, we show that the stellar images have the same diameter of 0.74" as the simultaneously measured seeing disk at the time of observation. We call our image "Engineering 1st Light" and in the near future expect to be able to produce images with diameters down to 0.3" in the R band over a 5.5' field during about 20% of the observing time, using the tip-tilt adaptive corrector we are implementing.

A low cost tip-tilt wavefront stabilization system has been put into operation on the Blanco 4-m telescope on Cerro Tololo. A light-weighted f/15 secondary mirror is driven by three commercial piezoelectric actuators. A dichroic at the Cassegrain focus separates optical reference and IR science beams. A steerable high-speed optical CCD sensor, coupled to a dedicated PC for control and image processing, provides positional feedback to the secondary. The IR field is reflected to one of several science sensors. We present a system description, initial performance measures at the telescope, and directions for future improvements.

The Dark Energy Survey Collaboration has completed construction of the Dark Energy Camera (DECam), a 3 square degree, 570 Megapixel CCD camera which will be mounted on the Blanco 4-meter telescope at CTIO. DECam will be used to perform the 5000 sq. deg. Dark Energy Survey with 30% of the telescope time over a 5 year period. During the remainder of the time, and after the survey, DECam will be available as a community instrument. All components of DECam have been shipped to Chile and post-shipping checkout finished in Jan. 2012. Installation is in progress. A summary of lessons learned and an update of the performance of DECam and the status of the DECam installation and commissioning will be presented.