Exact Market hours for each session?

Hi,
Can someone tell me the exact market hours.

Example NY session
Some sites show from 9:00 till 17:00 (NY TIME)
Some sites show from 8:00 till 17:00 (NY TIME)
Some sites show from 8:00 till 16:00 (NY TIME)

Same for London and Asia.

Some sites with non matching hours.

http://fxtrade.oanda.com/analysis/market-hours
http://www.babypips.com/school/trading-sessions.html
http://forex.timezoneconverter.com/

Because forex is a 24 hour market and not traded through an exchange it's not easy to be specific. As a rule of thumb most people use the opening/closing times of local stock exchanges. For example the London stock exchange opens at 8.00am GMT so that would be considered the start of the London session.

You can get detailed opening times on wikipedia of all exchanges http://en.wikipedia.org/wiki/List_of..._opening_times

You might find this chart handy (just about the only useful thing to come out of 4X Made Easy!!!)

http://i39.tinypic.com/2yydogm.jpg

Thanks to share wikipedia link for "List of market opening times". It is helpful for me as well.