Detectors and Data Analysis Techniques for Wide Field Optical Imaging

Summary

This contribution reviews the current status of optical wide field survey astronomy and the basic techniques that have been developed to capitalize on the large volumes of data generated by modern optical survey instruments. Topics covered include: telescope design constraints on wide field imaging; the properties of CCD detectors and wide field CCD mosaic cameras; preprocessing CCD data and combining independent digitized frames; optimal detection of images and digital image centering and photometry methods. Although the emphasis is geared toward optical imaging problems, most of the techniques reviewed are applicable to any large format two-dimensional astronomical image data.

Wide Field Survey Astronomy

Background

Astronomy is basically an observational science, rather than an experimental one, and the development and advancement of the subject has relied heavily on surveys of the sky at optical wavelengths to expand our knowledge of the observable Universe. Surveys form a basic foundation of observational astronomy, and provide three generic types of information:

1. (a) quantitative statistical information on the distribution of objects in our own galaxy and the Universe

2. (b) the ability to discover radically new types of object

3. (c) the means of selecting representative samples of certain types of (rare) objects, particularly the brightest examples, for further study with large telescopes.

Statistical surveys are beginning to rely ever more heavily on the wide field multi-object fibre spectroscopy capabilities of large telescopes, described elsewhere in this volume.