OmegaCAM: the VST camera

OmegaCAM, a single enormous optical CCD imaging camera, is the sole instrument of the VST. OmegaCAM and the VST will survey the sky to study a wide range of astrophysical domains, from the Solar System to the Milky Way and distant galaxies in the early Universe.

At the heart of OmegaCAM is a mosaic of 32 CCD detectors that creates images with a total of 268 megapixels — this equates to an impressive 26 x 26 cm and covers almost the entire VST field of view. This area is comparable to the highly successful SDSS camera of the Sloan Digital Sky Survey. OmegaCAM is set to operate with even better imaging quality and greater output — around 50 Gbytes of raw data every night, year after year.

Other design features of OmegaCAM include four auxiliary CCD cameras, two for auto-guiding and two for on-line image analysis. Up to 12 filters can be used, ranging from ultraviolet to near-infrared. The entire detector system operates in vacuum at about -140 degrees Celsius behind a large dewar window. This window not only protects the detectors from air and moisture, but also acts as an additional corrector lens.

An interesting feature of the OmegaCAM is the ability to switch between two different correctors. Depending on the observation angle, the user can choose the most convenient corrector via a mechanical switching unit. The first of these devices consists of two lenses made of fused silica and is ideal for observations close to the zenith in the sky. The second includes a rotating atmospheric dispersion corrector (ADC), coupled to one lens only, and is best suited when observing objects closer to the horizon.

The OmegaCAM consortium is comprised of institutes in the Netherlands (NOVA, in particular the Kapteyn Institute / OmegaCEN Groningen and Leiden Observatory), Germany (in particular the university observatories of Munich, Göttingen and Bonn) and Italy (INAF, in particular the Padua and Naples Observatories). The ESO Optical Detector Team provides the detector system.

For Scientists: Details for observers using VST are available at OmegaCAM at the VST