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Published online by Cambridge University Press: 12 April 2016
The SOLEX bragg crystal spectrometer experiment on the P78-1 satellite (Landecker, McKenzie and Rugge, 1979) has been used to determine accurate flux ratios of several strong solar Fe XVII x-ray emission lines in the ~ 15 to ~ 17 Å wavelength region. The ratios chosen were selected because the lines used permitted an accurate determination of the ratios both from the aspect of counting statistics as well as the lack of interference from other lines of comparable strength. Observations for a variety of conditions of solar activity, ranging from quiet conditions to large solar flares, are presented. For these observations intensity variations of a factor of about 60 were observed for the Fe XVII lines. Variations of a factor of almost 800 were observed for the Fe XVIII line at 14.2 Å. The observed ratios of the Fe XVII lines are compared to the theories of Loulergue and Nussbaumer (1975) and Smith, Raymond, Mann and Cowan (1984).