function rotation() {

	var length = picList.length;
	var rand = Math.floor(Math.random() * length);
	var img = "/media_assets/masthead_images/" + picList[rand];
	//document.write(img);

	var placeholder = document.getElementById("placeholder");
	placeholder.setAttribute("src", img);
	timer();

}

function timer() {
	
	update = setTimeout("rotation()", 4500);

}

window.onload = timer();