var z=3;
thun = new Array(z);
thun[0] = '<img src="../../images/fotos/alt01.jpg" class="img" width="530" height="150" alt="">';
thun[1] = '<img src="../../images/fotos/alt02.jpg" class="img" width="530" height="150" alt="">';
thun[2] = '<img src="../../images/fotos/alt03.jpg" class="img" width="530" height="150" alt="">';
var jetzt=new Date();
var z=(jetzt.getSeconds())%3;
document.write(thun[z]);