Observations of the stellar radiation field at 975 A

Stellar observations in the extreme-ultraviolet (EUV) portion of the spectrum have been conducted by means of sounding rocket experiments. The first photometric measurements below 1000 A were carried out from a rocket by Troy et al. (1975), who used channel electron multipliers with indium bandpass filters as detectors. The present investigation is concerned with results obtained with a simple wide-field photometer similar to that employed by Troy et al. However, in this case the photometer was carried by a satellite and most of the celestial sphere could be observed. Only a few stars were spatially isolated enough for individual flux determinations to be made. However, the measurements were well suited for the determination of the total stellar radiation field between 911 A and 1050 A. The STP 72-1 satellite, which carried the experiment, was launched into a circular 750 km altitude earth orbit in October 1972.