A 3-CHANNEL ASTRONOMICAL PHOTOELECTRIC SPECTROPOLARIMETER

A system has been developed for using a wave-length scanning polarimeter to determine the linear polarization parameters of astronomical sources through the visible spectrum, the spectral resolution depending only on the choice of the spectrometer. The spectrum is scanned in steps and at each wavelength setting three analyser positions are chosen and intensity measurements are made by a pulse counting photometer. Effects of intensity scintillation and changes in atomospheric transparency are overcome by a method of chopping and integration. The observational sequence and the final print-out are controlled electronically. Tests on the blue sky, the moon and stars are described.