ACAM is mounted permanently at a folded-Cassegrain focus of the 4.2-m William Herschel Telescope. It can be used for high-throughput broad-band imaging, narrow-band imaging and low-resolution spectroscopy.
The field of view in imaging mode is 8 arcmin (0.25 arcsec/pixel). A set of broad-band filters is available by default (usually Sloan u g r i z) but almost any of ING's filters can be mounted in ACAM.
Low-resolution spectroscopy over ~ 3500 - 9400 A is provided by a VPH disperser. For 1.0- and 0.5-arcsec slits, the on-axis spectroscopic resolutions at 6000 A are R ~ 450 and 900 respectively. At 7000 A, the throughput of ACAM is a factor ~ 1.5 times higher than that of ISIS.
ACAM, like its predecessor (the aux-port camera), is available whenever a prime-focus instrument is not in use, so is well-suited to observing override programmes and targets of opportunity.