Low frequency radio observations of the ‘background’ corona during the declining phase of solar cycle 24

Abstract

We studied the characteristics of the solar corona during the declining phase of solar cycle 24 using data obtained with the Gauribidanur RAdioheliograPH (GRAPH) near Bangalore in India. The observing frequencies were 80 MHz and 53 MHz. Radio emission corresponding to the above frequencies originate typically at heliocentric distances $\sim 1.5 \mathrm {R}_{\bigodot }$and $\sim 1.7 \mathrm {R}_{\bigodot }($where $\mathrm {R}_{\bigodot }$is the radius of the solar photosphere), respectively. Observations of only the ‘undisturbed’ corona, i.e. when there were no transient radio emissions and X-ray$/ \mathrm {H}\alpha $flares, were used for the present study. The period of observations was January 2015 to August 2018. The results obtained will be reported.