Two cylindrical metal rods of identical length \(L\) and cross-sectional area \(A\) are joined end-to-end between two thermal reservoirs maintained at constant temperatures \(T_H\) and \(T_C\), where \(T_H > T_C\). Rod 1 is in contact with the hot reservoir at \(T_H\) and has thermal conductivity \(k\), while Rod 2 is in contact with the cold reservoir at \(T_C\) and has thermal conductivity \(3k\). Assuming no thermal energy is lost through the sides of the rods, what is the temperature \(T_J\) at the junction between the two rods once a steady state is reached?