Interesting observations have been made possible by the success of the acousto-optical radio spectrograph, a unique form of multi-channel filter type of spectral receiver whose channel outputs ian be sampled at high rates by a computer. Three spectrographs are available at the Division of Radiophysics. Two divide a 100 MHz spectral range into 512 channels and are normally dedicated to spectral-line work (Cole and Milne 1977) and solar work (Cole et al. 1978). The Parkes observations reported here use a more compact spectrograph, which gives increased performance — up to 270 MHz can be studied, divided into 256 frequency channels. The light deflector of this spectrograph was kindly supplied by Itek Corporation.