Most distant object visible to the unaided eye...

[RobertM]

That assumes that you can see the sky in the first place of course...

http://www.astromart.com/news/news.asp?news_id=810

The explosion took place 7.5 billion years ago (redshift 0.98) before the earth had even come into existence and it was 2.5 million times more luminous optically than the most luminous supernova ever recorded.

The ghost of A.C. Clarke perhaps ?