A geometry problem by Aditya Bhattacharjee

A variable chord makes an intercept on the parabola $y^{2}$ = 4ax, at points having parameters $t_{1}$ and $t_{2}$ respectively. The variable chord subtends a right angle at a fixed point having parameter k , which lies on the same parabola. The variable chord passes through a fixed point. What are the coordinates of this fixed point in terms of k ??