The Glowing Circle texture node generates a greyscale glowing circle-like pattern (figure 1).
Figure 1: The Glowing Circle node applied to a scene object
Figure 2: The Glowing Circle node and it's associated parameters
Radius
Determines the radius of the circle.
Line Width
Determines the thickness of the line that produces the circle.
Transform
Positions, scales, and rotates the surface texture.
Projection
Sets how the texture projects onto the surface.