DOPPLER VELOCITY-MEASUREMENTS MADE WITH A SCANNING PHOTOELECTRIC MAGNETOGRAPH

We discuss the problems connected with the measurements and evaluation of line-of-sight velocities, obtained with a scanning photoelectric m agnetograph using a line-shifter with enhanced sensitivity. We bring a rguments for the validity of the results of our photoelectric Doppler velocity recordings. We have found a network of cellularly shaped patt erns in the distribution of photoelectrically measured line-of-sight m otions, upflowing in the magnetically quiet (blue-shifted) and downflo wing in magnetically active (red-shifted) areas of the photosphere, if the mean velocity level is estimated for a sufficiently large measure d area. The features of both directions are mutually complementary. We demonstrate the effect of the shift of the reference zero velocity le vel on the topology of the line-of-sight velocity maps, and the depend ence of this level on the size of the area from which it is estimated.