Time zone handling in php

Question

I am working on rss parser project, I need to fetch URL from us based server and store the data in to database while storing/viewing I need to keep the post time. I am using simplepie for rss aggregation, I face the following problem while handling rss

while I am checking rss url in firefox 3.0.19/system timezone set to Chennai/Kolkatta/Mumbai(UTC+5:30)now firefox displays post time for the post is 10:51 am at the same time if i check the same url in another system which has firefox 3.6.1/system timezone set to Chennai/Kolkatta/Mumbai(UTC+5:30) now firefox displays post time for the post is 11:34 am

how do I know which time is correct? and how do I get timezone for the RSS Server for php

RSS Feeds stored in one server and I installed PHP application in another server both of them located in us.

Which timezone should I use?

i set following time zone in my code

<?php
  date_default_timezone_set('US/Central');
  ?>

but post time is wrong when display

Answer 1

i solved the problem my self using below method

get list of all timezones take first post's post date and set the first timezone format the date and set the second timezone format the date and so on.. finally i compared formatted date with postdate then i got the timezone of the server