Board Thread:The Panopticon/@comment-70.181.189.34-20130621211739/@comment-188432-20130623153109

Yes, and the reason it's at 18:30 UTC is because that's actually 17:30 GMT, which is close to the actual time that "An Unearthly Child" went out. (This question has prompted me to not be so lazy in my approximation, and instead reset it for 18:16:20, the exact time to the second that it went out, 80 seconds late due to the news coverage of the JFK assassination.)

It's definitely not a countdown to the probable broadcast of the 50th anniversary special. Not sure why the OP thinks it's set to Pacific Daylight Time.