The tethered sounding rocket payload OEDIPUS A conducted bistatic propagation experiments on plasma waves in the auroral ionosphere. Synchronized sweeps of the frequency range 0--5 MHz by the 2-W transmitter high-frequency exciter (HEX) on the upper end of the tether and its associated receiver for exciter (REX) on the lower end have produced signatures of quasi-electrostatic waves guided along field-aligned depletions of ambient density. The propagation is in the slow Z mode, between the plasma frequency fp and the upper hybrid resonance frequency fuhr when fp is greater than the cyclotron frequency. The mode identification is based on payload measurements of fp. These waves have signal delays of about 1 ms. The delays are much greater than expected for free-space propagation over the transmitter-received separation distance which varies up to 960 m during the flight. The transmitted pulses typically appear inside a frequency bandwidth of about 100 kHz just above the plasma frequency, but occasionally occupy most of the available bandwidth, ≂300 kHz, between fp and fuhr. The observed delays and the stretching by a factor of 3 of the transmitted 300-&mgr;s pulses are accounted for with two-dimensional ray tracing using a complete electromagnetic solution of the hot plasma dispersion relation. Delayed Z mode pulses appear in about 20% of the ionograms. Given the weakness of the HEX transmitter and the abundance of examples obtained during the flight, guiding of natural Z mode emissions in the auroral ionosphere may be efficient and widespread. ¿American Geophysical Union 1991