Photon Counter Measurements of Solar X-Rays and Extreme Ultraviolet Light

Data telemetered continuously from photon counters in a V-2 rocket, which rose to 150 km at 10:00 A.M. on September 29, 1949, showed solar 8A x-rays above 87 km, and ultraviolet light around 1200A and 1500A above 70 km and 95 km, respectively. The results indicated that solar soft x-rays are important in $E$-layer ionization, that Lyman $\alpha$-radiation of hydrogen penetrates well below $E$-layer, and that molecular oxygen is rapidly changed to atomic above 100 km.