The auroral green line in Perseid spectra near sunspot maximum

Thirty-one spectra photographed during the Perseid showers of 1969 and 1970 are found to exhibit greater ionization and stronger, more frequent appearance of the forbidden oxygen line at 5577 A than Perseid spectra obtained with the same instrument in 1961. Data from 13 Perseid showers indicate a relationship between the frequency of occurrence of the oxygen line and solar activity. In 1969-70, near sunspot maximum, the strength of this auroral green line is greatest near shower maximum, as though the nature of the meteoroids were a function of their distance from the core of the stream, or, alternatively, the strength of the green line were a function of the altitude of the radiant.