The response of the ionospheric F region to the large solar flare that occurred near 1500 UT on August 7, 1972, has been monitored by means of Faraday rotation measurements made at 17 stations in North America, Europe, and Africa. With observations spanning more than 10 hours in local time and more than 70 deg in latitude, the first truly global morphology of a flare‐induced F region event was obtained. The sizes of the individual sudden increases in the total electron content (Sitec) ranged from 1.8 to 8.6 × 1016 el/m²; on a percentage basis, all the Sitec fell within the 15 to 30% range. No obvious relationship was found between the sizes of the increases and the solar zenith angles at the various subionospheric points, nor between the observed Sitec and the sudden flare effects (SFE) seen on nearby magnetometer recordings. The latitudinal behavior provided the only simple ordering parameter found in the data, the lower latitudes having larger observed increases than the higher latitudes. Millstone Hill incoherent scatter data showed that nearly 40% of the total content enhancement observed at that site came from heights above 300 km. All the Sitec had a rise time of about 10 min, during which the Tec rate of change showed an excellent correlation with the time development of the solar radio burst monitored at 35,000 MHz.

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As part of the Apollo‐Soyuz Test Project (ASTP), Apollo was tracked in the satellite‐to‐satellite tracking mode by the NASA synchronous satellite ATS‐F. The tracking data obtained at occultation of Apollo by the earth has been used in this study to compute atmospheric parameters like pressure and temperature. The results of the numerical inversion have been compared with data from a radiosonde station near the occultation site. Although this comparison lacks exact space‐time coincidence because of the paucity of the data, it is of interest to report that near the surface of the earth, the refractivity computed from occultation data agreed with the radiosonde‐derived values to within 3 percent. A pressure profile deduced from the refractivity profile by using a simplified model of the atmosphere showed good agreement with radiosonde measurements. Although the present results are based on one occultation pass and lack statistical validity, they demonstrate the feasibility of determining absolute pressure levels in the atmosphere from occultation measurements.