Luminosity near the active dipoles in the OEDIPUS-C ionospheric experiment

The OEDIPUS-C sounding rocket double payload was designed for two-point studies of plasma waves in the auroral ionosphere. Early in the experiment, just after the two subpayload parts began to separate, a television camera on the aft subpayload began to record intense visible radiation near the transmitting dipoles on the forward subpayload. This luminosity reduced to zero in the 15 seconds that it took an argon gas thruster bottle to evacuate completely. The luminosity is interpreted as the result of collisional excitation by sounder-accelerated electrons of argon atomic levels that subsequently decay by transitions at visible wavelengths.