Coordinate Geometry: JEE Main 2021 Mathematics question

Consider a triangle having vertices A($-$2, 3), B(1, 9) and C(3, 8). If a line L passing through the circum-centre of triangle ABC, bisects line BC, and intersects y-axis at point $\left( {0,{\alpha \over 2}} \right)$, then the value of real number $\alpha$ is ________________.