Introduction

The UK scientific community has access to outstanding astronomical observations at all wavelengths from radio to X-ray. The interpretation of these can often only be achieved by a quantitative comparison between an observed spectrum and a theoretical model. Sophisticated calculations of atomic, chemical and radiative processes in the emitting plasma, as well as self-consistent models of the objects themselves, can lead to the inferrence of fundamental properties of the emitter (e.g. kinetic temperature, electron density, chemical composition, geometry, dynamics and stratification). These calculations depend on realistic algorithms, large quantities of atomic and molecular data, and substantial computational resources.

CCP7 is concerned with providing the UK and wider astronomical community with access to suitable resources, particularly in the domain of stellar atmospheres and the interstellar medium. It pursues specific research objectives in a number of selected areas and plays a key role in providing a communication channel between astronomers, physicists and chemists with common interests. CCP7 maintains an unrivalled software library useful for modelling astronomical spectra, with software available under the following headings: