On modulations of radio type IV bursts

Observations of a pulsating source which constitutes the early beginning of the type IV continuum are reported. The emission starts with about one hundred pulses followed by a continuous emission moving with the same apparent speed of 350 km/s. The total duration of the event is 10 min. The main characteristics of the pulses are: periodicity (1.7 + or - 0.5)s, diameter 200,000 km, modulation greater than 90%, brightness temperature greater than or equal to 10 to the 9th K, frequency bandwidth 140-250 MHz, and frequency drift about 300 MHz/s. It is pointed out that further research is necessary to explain these observations.