Rotate around with min/max Angle

Hi,

i want to rotate around the center Object, but with min/max Angles.
my script works with 360°, but i can't limit the rotation.

Have somebody an idea? Thank you very much.

alt text

    using UnityEngine;
    using System.Collections;
     
    public class RotateAroundScript : MonoBehaviour {
     
        public Transform center;
        public float rotationSpeed = 80.0f;
        public Vector3 axis = Vector3.up;
     
        public Transform PlayerFlip;
        public float speed = 1.5f;
     
     
     
        void Update ()
        {
            if (Input.GetKey (KeyCode.UpArrow) && PlayerFlip.localScale.x ==1)
            {
                transform.RotateAround (center.position, axis, rotationSpeed* Time.deltaTime);
     
            }
            if (Input.GetKey (KeyCode.DownArrow) && PlayerFlip.localScale.x ==1)
            {
                transform.RotateAround (center.position, -axis, rotationSpeed* Time.deltaTime);
     
            }
     
            if (Input.GetKey (KeyCode.UpArrow) && PlayerFlip.localScale.x ==-1)
            {
                transform.RotateAround (center.position, -axis, rotationSpeed * Time.deltaTime);
     
            }
            if (Input.GetKey (KeyCode.DownArrow) && PlayerFlip.localScale.x ==-1)
            {
                transform.RotateAround (center.position, axis, rotationSpeed * Time.deltaTime);
     
            }
        }

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