Stop camera rotation when x axis = 90

I’m using the following code to rotate a camera while looking at an object. I’m having some real problems trying to stop the camera when the camera’s x axis =90 degrees. I can’t find out how to reference this value that I can see in the inspector…

var target : Transform;
    function Update() {
    	transform.RotateAround (, Vector3(1,0,0), 5 * Time.deltaTime);

You can access the x,y,z of rotation through the euler functions:

This article should be very helpful in learning how transform.rotation relates to the Euler angles you see in the inspector: