FIELD: plotting of two-dimensional charts of radial velocities of astrophysical or other objects by Doppler shift of spectral line measured by method of line scanning by bandwidth of interference-polarization filter. SUBSTANCE: for compensation of effect of shift of bandwidth of uncontrollable elements of interference-polarization filter on measurement of line shift their band is formed with two maxima distance between which is 20-30% greater than scanning value of controllable elements. Depth of minimum between maxima lies within limits of 40-60% of their intensity. If due to thermostating error bandwidth of uncontrollable elements shifts relative to center of scanned band of controllable elements and " dark blue " and : red " outlines of scanned band fall on sections of outline of double maximum then difference of signals with two positions of scanned band is caused by line shift only. EFFECT: improved reliability of method. 2 dwg
