Flux of Solar XUV Radiation Inferred From Ionospheric Variations During the Eclipse of $20^{th}$, May 1966

M. Vukićević-Karabin

The primary photon interactions and associated effects of Solar X-rays and ultraviolet (UV) radiation are of greatest importance to the structure of the Earth's atmosphere above 100 km. This part of the upper atmosphere which is mostly under control of incident Solar XUV ($\lambda = 30 - 1750 {\AA} $). is commonly called ionosphere. First of all, it is important to emphasize the fact that only little direct experimental data of absolute flux of incident Solar XUV radiation has been accumulated over the period of the Quiet Sun (1963 - 1966). Data from satellite experiments are available only for certain wavelength bands. There are only several satelllte data of incident Solar flux. $\lambda=170-1027 {\AA}$ which is of dominant importance for ion production in the atmosphere above 100 km under quiet conditions. That is why estimation of Solar XUV flux ($\lambda = 170 - 1027 {\AA} $)fromionospheric measurements during Solar eclipse of $20^{th}$ May, 1966 contributed to fill up deficiency in knowledge about this part of Solar spectrum.