Correlated Oscillations Due to Similar Multipath Effects Seen in Two Widely Separated Radio Telescopes

Abstract

A multipath mechanism similar to that used in Australia sixty years ago by the Sea-cliff Interferometer is shown to generate correlations between the periods of oscillations observed by two distant radio telescopes pointed to the Sun. The oscillations are the result of interferences between the direct wave detected in the main antenna lobe and its reflection on ground detected in a side lobe. A model is made of such oscillations in the case of two observatories located at equal longitudes and opposite tropical latitudes, respectively in Ha Noi (Viet Nam) and Learmonth (Australia), where similar radio telescopes are operated at 1.4 GHz. Simple specular reflection from ground is found to give a good description of the observed oscillations and to explain correlations that had been previously observed and for which no satisfactory interpretation, instrumental or other, had been found.

Evidence for Polarized Solar Flare Emission From Simultaneous Radio Observations in Australia and Vietnam

“…As a by-product of observations [1,2] of the Sun using the VATLY radio telescope [3,4], a sample of 34 solar flares [5] observed simultaneously in Hanoi and Learmonth [6] has been collected. These observations provide interesting material for a study of the perfomance of the VATLY radio telescope under conditions of important and rapid changes of the signal with time.…”