use DateTime to get different timezone date.
php > $date = new DateTime('2000-01-01', new DateTimeZone('Pacific/Nauru'));
php > echo $date->format('Y-m-d H:i:sP');
2000-01-01 00:00:00+12:00php >
php > $date->setTimezone(new DateTimeZone('Pacific/Chatham'));
php > echo $date->format('Y-m-d H:i:sP');
2000-01-01 01:45:00+13:45php >
php > $date->setTimezone(new DateTimeZOne('UTC'));
php > echo $date->format('Y-m-d H:i:sP');
1999-12-31 12:00:00+00:00php >
