I've an Apache directory report on files on the remote server (around australiaOrAdelaide +930) I've no treatments for. This server shows the right last modified date of the file as: 14-August-2009 09:41

I've got a PHP script on my small US server to determine the date from the remote file. get_headers()['Last-Modified'] returns: Comes to an end, 14 August 2009 00:11:11 GMT

How do you get my PHP script to output just like Apache?

You are in Adelaide, Australia, that is GMT +9:30. get_headers() is providing you with GMT time. apache is providing you with local time.

The HTTP headers which returns from get_headers() is pushing out GMT time per the HTTP standard. What's your time and effort zone in your server?