The transverse motions of the sources of solar radio bursts

Abstract

Observations of the spectrum of solar radio bursts at meter wavelengths have indicated the desirability of measuring positions on the sun's disk not only as a function of time but also as a function of frequency. With this objective in view, we are now using a swept-frequency interferometer to determine the east-west disk coordinate of the transient solar sources at time intervals of ½ second and freqency intervals of about 5 Mc/s within the frequency range 40 to 70 Mc/s. The accuracy to which the centroid of the source is located is about ±1 minute of arc. In its initial form [1], the interferometer contained two aerials separated by a distance of 1 km. As a result of preliminary tests, two major additions have been made: (1) a second interferometer of much smaller spacing (¼ km) has been added to resolve the usual ambiguities associated with two-aerial interferometry, and (2) an automatic system of lobe-switching and phase-calibration has been incorporated to facilitate the reduction of the complex data recorded.