function showmap(loc) {
  var ah = screen.availHeight;
  var aw = screen.availWidth;
  var wh = 780;
  var ww = 600;
  var ll = (ah - wh) / 2;
  var rr = (aw - ww) / 2;
  window.open(loc,'MAP','scrollbars=0,toolbars=0,width='+ww+',height='+wh+',left='+rr+',top='+ll+'screenX='+rr+',screenY='+ll);
}