A series of twilight interferometric observations of the near infrared O+(2P) doublets at 7320 and 7330 ¿ between April 1979 and October 1979 detected excessive amounts of emission at shadow heights above 550 km. The scale height deduced from the vertical brightness profile determined from data taken on September 26, 1979, when the F10.7 was 231, showed a marked increase above 550 km. The equivalent temperature was estimated to be 4000 ¿K or higher. Observations of the emission line shape with the high-resolution capability of the interferometer substandiated these results by a very apparent progressive broadening of the emission profile between times of low and high shadow height. We conclude from these results that there exists an atomic oxygen corona overlying the thermosphere during the solar maximum period.