Ultraviolet and VUV sources for in-flight calibration of space experiments

The importance of calibration subsystems as part of overall system design has grown with the increasing sophistication and complexity of remote sensing and imaging instruments. In general they provide spectral and radiometric reference data in-situ under remote and sometimes unpredictable instrument conditions which are used to correct electronic, optical and detector nonlinearities. The recent difficulties with GOES satellites underline the importance of reliable calibration sources for space applications. Although the calibration component is a small fraction of the budget of any space qualified instrument, its failure can result in a catastrophic loss of data. A group of sources will be described which have been developed for in-flight and pre-flight calibration of a variety of space astronomy and space physics experiments with different requirements in terms of wavelength coverage, power budget, size requirements and radiation hardness.