x = parseInt(window.screen.width) / 2 - 250;  // the number 250 is the exact half of the width of the pop-up and so should be changed according to the size of the pop-up
y = parseInt(window.screen.height) / 2 - 150;  // the number 150 is the exact half of the height of the pop-up and so should be changed according to the size of the pop-up

function infoPop(URL) {
day = new Date();
id = day.getTime();
CW = eval("page" + id + " = window.open(URL, '" + id + "', 'toolbar=0,scrollbars=1,location=0,statusbar=0,status=no,status=0,statusbar=no,menubar=0,resizable=1,width=500,height=300,top=50,left=50');");
CW.moveTo(x,y);
}