Sunspot observations by means of a vidicon camera (I)

In our electronic method, the circular sunspots are recorded on a magnetic video tape recorder, and then the recorded images of them are reproduced on a picture monitor and the video signals are simultaneously displayed on an oscilloscope. By means of a line selector, the waveform of a single scanning line of the total raster may be photographed immediately. From these successive waveforms we may directly calculate the relative brightness from the ratio of the voltage of the spot to that of the photosphere and the brightness gradient over the whole spot area. Usually we can get all these results of an individual spot within two or three days.As typical examples, as shown in Table I, we selected five circular spots of medium scale from many recorded data and explained their characteristics. We can get more accurate results if we would use a standard image orthicon camera. Our new method may be effective if being applied to a large telescope, and also it may be valid for several spectroscopic observations.