We report a solar coronal split-band type II radio burst that was observed on 2016 March 16 with the Gauribidanur Radio Spectro-Polarimeter ( GRASP ) in the frequency range \approx 90 - 50 MHz , and the Gauribidanur RadioheliograPH ( GRAPH ) at two discrete frequencies , viz .
80 MHz and 53.3 MHz .
Observations around the same epoch in extreme-ultraviolet ( EUV ) and white-light show that the above burst was associated with a flux rope structure and a coronal mass ejection ( CME ) , respectively .
The combined height-time plot generated using EUV , radio , and whitelight data suggest that the different observed features ( i.e .
the flux rope , type II burst and the CME ) are all closely associated .
We constructed an empirical model for the coronal electron density distribution ( N _ { e } ( r ) , where r is the heliocentric distance ) from the above set of observations themselves and used it to estimate the coronal magnetic field strength ( B ) over the range of r values in which the respective events were observed .
The B values are consistent with each other .
They vary as B ( r ) = 2.61 \times r ^ { -2.21 } G in the range r \approx 1.1 - 2.2 R _ { \odot } .
As far as we know , similar ‘ direct ’ estimates of B in the near-Sun corona without assuming a model for N _ { e } ( r ) , and by combining co-temporal set of observations in two different regions ( radio and whitelight ) of the electromagnetic spectrum , have rarely been reported .
Further , the present work is a novel attempt where the characteristics of a propagating EUV flux rope structure , considered to be the signature of a CME close the Sun , have been used to estimate B ( r ) in the corresponding distance range .