INSTRUMENTATION FOR X-RAY ASTRONOMY

Less than five decades ago, the first X-ray observations of the sky we re made using simple devices such as film and geiger counters with cru de collimators. These instruments were carried aloft by sounding rocke ts and made observations lasting only a few minutes at most. Today, or biting observatories, utilizing high-resolution CCDs at the focus of a rc sec optics, have lifetimes measured in years. To maintain the pace of discovery in X-ray astronomy, detectors must continue to evolve int o devices of ever increasing sensitivity and sophistication. Further p rogress depends upon a host of technologies: grazing incidence optics, proportional counters, semiconductors, calorimeters, etc. In this art icle we present a brief qualitative overview of these technologies and of the principles behind them, as well as some examples of how they a re employed in scientific missions for X-ray observations at energies up to 100 keV.