The data have been normalised for a star with m = 10 and for 100 sec integrations. In each case the signal, averaged over 2,mm of spectrum, is in ADUs integrated across a 22,m (1 pixel) section of the spectrum. The conversion of ADUs for the camera in use was 1 ADU = 1 electron approximately. The electronic readout noise was 6 to 7 electrons per pixel per readout. The spectrum with normal seeing and and manual guiding was typically 5 pixels wide.