HS-Trixxxia

I have a code that is supplied to me from a sponsor that rotates the galleries in the database with every refresh. I'd like that simple code to rotate only after 24 hours. Anybody have the secret?

<?php
$fileName = "./bobotheclown.txt";
mt_srand( (double) microtime() * 1000000 );
$a = file($fileName);
$randNum = mt_rand( 0, sizeof($a)-1 );
header( "Location: ". $a[$randNum] );
?>


Thanks

Trixxxia