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Non-ducted Omega signals and associated ASE (Artificially Stimulated Emission) triggered by the Omega transmitter located at Aldra (66°25′15″N, 13°09′10″E, geographic) in Norway were observed by ISIS-I and -II satellites. During the period from May 30,1976 to February 8,1980,VLF data including Omega signals were obtained for 42 out of 642 passes. VLF emissions triggered by the Omega transmitter were detected only for 8 passes out of these 642 passes. Most of the 42 passes were observed within ±15°of geomagnetic meridian through Aldra. Furthermore, the probability of the Aldra signal detection is relatively high in the daytime and for low Kp value mostly less than 3. IN spite of the fact that Aldra is located in high latitude, the delay times of direct pulses to ISIS-I and -II satellites in the conjugate hemisphere were between 0.8 and 1.5s in the L range of 2.4 to 4. The beginning latitude of each frequency component indicates that the frequency coincides with a quarter of minimum electron gryofrequency on a field line passing through the observing point.