The Dark Energy Camera (DECam) was developed for use by the Dark Energy Survey (DES). The camera will be
installed in the Blanco 4M telescope at the Cerro Tololo Inter-American Observatory (CTIO) and be ready for
observations in the second half of 2012. The focal plane consists of 62 2×4K and 12 2×2K fully depleted CCDs. The
camera provides a 3 sq. degree view and the survey will cover a 5000 sq. degree area. The camera cage and corrector
have already been installed.
The development of the electronics to readout the focal plane was a collaborative effort by multiple institutions in the
United States and in Spain. The goal of the electronics is to provide readout at 250 kpixels/second with less than 15erms
noise. Integration of these efforts and initial testing took place at Fermi National Accelerator Laboratory. DECam
currently resides at CTIO and further testing has occurred in the Coudé room of the Blanco. In this paper, we describe
the development of the readout system, test results and the lessons learned.
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.
The Dark Energy Survey makes use of a new camera, the Dark Energy Camera (DECam). DECam will be installed in the Blanco 4M telescope at Cerro Tololo Inter-American Observatory (CTIO). DECam is presently under construction
and is expected to be ready for observations in the fall of 2011. The focal plane will make use of 62 2Kx4K and 12
2kx2k fully depleted Charge-Coupled Devices (CCDs) for guiding, alignment and focus. This paper will describe design
considerations of the system; including, the entire signal path used to read out the CCDs, the development of a custom
crate and backplane, the overall grounding scheme and early results of system tests.
The goal of the Dark Energy Survey (DES) is to measure the dark energy equation of state parameter with four
complementary techniques: galaxy cluster counts, weak lensing, angular power spectrum and type Ia supernovae. DES
will survey a 5000 sq. degrees area of the sky in five filter bands using a new 3 deg2 mosaic camera (DECam) mounted
at the prime focus of the Blanco 4-meter telescope at the Cerro-Tololo International Observatory (CTIO). DECam is a
~520 megapixel optical CCD camera that consists of 62 2k x 4k science sensors plus 4 2k x 2k sensors for guiding. The
CCDs, developed at the Lawrence Berkeley National Laboratory (LBNL) and packaged and tested at Fermilab, have
been selected to obtain images efficiently at long wavelengths. A front-end electronics system has been developed
specifically to perform the CCD readout. The system is based in Monsoon, an open source image acquisition system
designed by the National Optical Astronomy Observatory (NOAO). The electronics consists mainly of three types of
modules: Control, Acquisition and Clock boards. The system provides a total of 132 video channels, 396 bias levels and
around 1000 clock channels in order to readout the full mosaic at 250 kpixel/s speed with 10 e- noise performance.
System configuration and data acquisition is done by means of six 0.8 Gbps optical links. The production of the whole
system is currently underway. The contribution will focus on the testing, calibration and general performance of the full
system in a realistic environment.
The Dark Energy Survey Collaboration is building the Dark Energy Camera (DECam), a 3 square degree, 520
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. Construction of
DECam is well underway. Integration and testing of the major system components has already begun at Fermilab and
the collaborating institutions.
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 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.