Wide-Field CCD Imaging at CFHT: The MOCAM Example

We describe a new 4096x4096 pixel CCD mosaic camera (MOCAM) available at theprime focus of the Canada-France-Hawaii Telescope (CFHT). The camera is amosaic of four 2048x2048$ Loral frontside-illuminated CCDs with 15 $\mu$mpixels, providing a field of view of 14'x14' at a scale of 0.21''/pixel. MOCAMis equipped with B, V, R and I filters and has demonstrated image quality of0.5''-0.6'' FWHM over the entire field. MOCAM will also be used with the CFHTadaptive optic bonnette and will provide a field of view of 90'' at a scale of0.02 ''/pixel. MOCAM works within the CFHT Pegasus software environment andobservers familiar with this system require no additional training to use thiscamera effectively. The technical details, the performance and the first imagesobtained on the telescope with MOCAM are presented. In particular, we discusssome important improvements with respect to the standard single-CCD FOCAMcamera, such as multi-output parallel readout and dynamic anti-blooming. Wealso discuss critical technical issues concerning future wide-field imagingfacilities at the CFHT prime focus in light of our experience with MOCAM andour recent experience with the even larger UH 8192x8192 pixel CCD mosaiccamera.Comment: Accepted for publication in Publication of the Astronomical Society of the Pacific. Latex with aas2pp4.sty and epsf.sty. 12 pages, 10 figure