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Dark Energy Camera (DECam)

Introduction

DECam is the new high-performance, wide-field CCD imager for the prime focus of the Blanco 4-m telescope
at CTIO. The DECam imager contains 62 CCDs for science with 520 megapixels, and at the Blanco telescope's
prime focus, will image 3 square degrees (2.2 degree wide field) at 0.27 arcsecond/pixel resolution.

The camera was built as part of the Dark Energy Survey (DES) Project by the DES Collaboration,
which is a Fermilab-led international collaboration of over 120 scientists from 15 institutions and consortia
in the USA, UK, Spain, Brazil and Germany. DECam is a facility instrument, available for all users (tentatively)
starting in late 2012. The DES Collaboration, in exchange for the instrument and a community pipeline will receive
525 nights over 5 years to carry out the Dark Energy Survey. The project is funded by the DOE and NSF,
the funding agencies of the UK, Spain, Brazil, and Germany, and contributions from the Collaboration institutions.

Latest News

2012 December 1: Community Observing begins again.
2012 November 10: Check with support astronomer or telops for new saftey precautions for DECam operation.

Overview of DECam

2.2 degree wide field of view (3 sq degree), 520 megapixel imager, 0.27 arcsec/pixel
New Prime Focus cage and 5-element optical corrector 62 2Kx4K LBNL red-sensitive CCDs, (QE 60% at 0.4 mu, 90% at 0.9 mu).
Full frame read time is 30-40 seconds, with a read-noise of 7 e-/pixel.
u,g,r,i,z,Y filters. Filter transmission curve data and transmission plot, as measured by Asahi.
A hexapod that can be driven by the wavefront sensor CCDs and from laser alignment sensors will provide active control of focus and alignment.
A "Community Pipeline" (CP) operated by NOAO will process raw DECam images and calibration frames into processed images (single and stacked frames, astrometric and rough photometric solutions). The abilities of the CP during Science Verification and the 2012B semester may be limited to producing single frames with crosstalk removal and corrected by zero and flat field frames. In addition, the operability of the CP is expected to be substantially improved by mid 2013, prior to there may be difficulty in keeping up with the production of reduced data.
Both raw and reduced data will be served from NOAO Science Archive.
Preliminary Exposure Time Calculator (Excel spreadsheet, courtesy of Darren DePoy). This ETC includes the as-built optics tranmissions, filter transmissions and CCD quantum efficiencies, as a function of wavelength. It should give reasonable estimates for stellar photometry with DECam, but it gives optimistic results for extended objects such as galaxies. Efforts are underway to provide reliable extended-object photometry in the DECam ETC.