CFHT, Instruments, Imaging, FOCAM, Introduction.

Canada-France-Hawaii Telescope

A User's Manual for the CFHT Visible Imager: FOCAM



The outstanding image quality routinely available at CFHT has been constantly revealed with FOCAM observations. This manual intends to provide you with the best possible information and observing procedures to allow a most efficient use of this facility.

All instruments and systems at CFHT are in constant evolution; so are the manuals. The "User's Manual for CFHT CCDs" last updated by Carol Christian in 1988 has been an important source of information for the initial redaction of this manual. New information has been added and the manual re-organized by Olivier Lefevre in 1991, and for the first time distributed electronically via ftp of a postscript file. However, differences in postscript formats and printer drivers precluded a widespread use of the electronic version. This is the main reason why most CFHT manuals have been converted into html format and offered on Mosaic. On the occasion of this reconversion, the manual has been updated to take into account the latest evolutions of hardware and software.

We have made an important use of the hyperlink structure offered by Mosaic. Therefore, this manual may not be easy to print out in its integral version; this is not the philosophy behind the devolopment of these manuals. They aim at providing a quick and easy, reliable and up-to-date on-line information of CFHT systems and instruments. However, a few pages or tables or figures are certainly easy to print out for later references. We have assumed that Ghostview and Xview are available at your site for visualization of the figures. For any help, questions or suggestions on this manual, contact Dennis Crabtree at

Scope of this Document

This manual describes the instrumental set-up, the control software, the observing procedures, as well as the data reduction procedures involved for direct imaging at CFHT with FOCAM, both at the prime and Cassegrain focii. The information provided here is as complete as possible at the time of this writing, and it is to your advantage to read this manual carefully prior to your run. The User's Interface for the CFHT CCD mosaic MOCAM, is very similar to FOCAM. It is pertinent to read this manual if you intend to use MOCAM at the telescope. At the time of this writing, CFHT direction is negotiating with IfA to make available to the CFHT community a 8Kx8K mosaic of CCD. However, this instrument has not been integrated in CFHT environment, and there is no PEGASUS interface for it at this time.

FOCAM is probably the simplest instrument used at CFHT. This implies that the data acquisition efficiency can be very high if you are well prepared. Your cycle time between successsive exposures on different targets could be limited only by telescope pointing or CCD readout time, whichever is the longest. CFHT Pegasus User's Interface and controlled systems are designed to provide you with the most straightforward and efficient means of instrument control and observing procedures. This manual will hopefully allow you to attain a maximum observing efficiency to make the best use of those famous Mauna Kea nights.

Please send comments to Dennis Crabtree at