It is well known that magnetic field strength ( B ) in the solar corona can be calculated using the Alfvén Mach number ( M A ) and Alfvén speed ( v A ) of the magnetohydrodynamic shock waves associated with coronal type II radio bursts. We show that observations of weak circularly polarized emission associated with the harmonic component of the type II bursts provide independent and consistent estimates of B . For the coronal type II burst observed on 2021 October 9, we obtained B ≈1.5 G and ≈1.9 G at a heliocentric distance ( r ) of ≈1.8 R ⊙ , using the above two techniques, respectively.

The Indian Institute of Astrophysics (IIA) has commissioned a low frequency (<100 MHz) spectrograph at its Kodaikanal Solar Observatory (KSO) for coordinated observations of transients in the solar atmosphere with other existing optical observing facilities there. The hardware set-up and initial observations are presented. The availability of different instruments in the same observatory helps to quickly plan and jointly observe the energetic phenomena and their signatures in all the three major atmospheric regions of the Sun, i.e. photosphere, chromosphere and corona.