arImages=new Array(
  "images/masthead1.gif",
  "images/masthead2.gif",
  "images/masthead3.gif"
  
);

rand=Math.floor(arImages.length*Math.random());
document.write('<img src="'+arImages[rand]+'" width="498" height="119" alt="alt="Photographic Images of residents of OLPNA"">');