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Published online by Cambridge University Press: 14 August 2015
Five meteoric spectra have been studied that were obtained during the period mid-June to mid-December, 1966. They include spectra of a Perseid, a Geminid, and three sporadic meteors. Four were photographed on Royal Pan emulsion without a filter; the Geminid on Tri X Aerecon with a GG11 filter.
Lines in the spectrum of one of the sporadic meteors indicate that two meteoroidal fragments were involved which diverged with increasing atmospheric penetration and which flared at different altitudes, indicating that the flares were not the result of atmospheric stratification.
The second sporadic and the Perseid were photographed about 2½ hours apart. The sodium D line is strong in the Perseid but does not appear in the sporadic spectrum. If present, it is blended with the diagonal sequence Δv = + 4 of the first positive group of the neutral nitrogen molecule, which appears in both spectra. A line questionably identified as the forbidden line of oxygen at 5577 Å appears faintly in the sporadic. The strength of the N2 sequence in these two spectra, and the absence of the D line in the sporadic, are very unusual. The proximity in time of appearance of these two spectra, and the absence of the N2 bands from the other two sporadic spectra, suggest that a temporary atmospheric condition may be responsible for the strength of the nitrogen radiation.
The Geminid has as its principal feature the Δv = + 3 sequence of the first positive group of N2. We have not previously observed this band in meteors as low in velocity as the Geminids.