Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE · 2008 · 47 citations · 0 references
Natural SciencesAstronomyPhysicsObservational AstronomyOptical AstronomyOpticsFar-infrared AstronomyGamma-ray TelescopesNear-infrared AstronomyRadio TelescopesSpace-based Gamma-ray ObservatoriesTelescope OpticsBroad-band ImagingFiltersGamma-ray ImagingNarrow-band ImagingOptical Telescope SystemsTelescopesVariable Filters
ACAM will be mounted permanently at a folded-Cassegrain focus of the WHT. It can be used for broad-band or narrow-band optical imaging of an 8.3-arcmin field, or for low-resolution (R ~ 500) spectroscopy. As the only wide-field optical imager at the Cassegrain focus, ACAM is designed to cater for a broad range of science programmes, including those requiring rapid response (e.g. gamma-ray bursts, supernovae) or scheduling at awkward intervals (e.g. successive exoplanet transits), and those requiring the use of many filters (e.g. <i>H<sub>α</sub></i> mapping of low-redshift galaxies). The imaging requirements alone are demanding, requiring a trade-off between field of view (> 8 arcmin), PSF (<< seeing), wavelength coverage (UV to near-IR), throughput (> 0.8) and radius-dependent wavelength shift (< 0.5 nm, for narrow-band filters). We discuss how the trade-off was effected and present the final optical and mechanical design, and the expected performance.