Before our time. .. yet bright enough to see

A gamma ray burst coming from the direction of the constellation of Bootes started on its way to us some 7 bllion years ago and reached here a few nights ago in a suddens surge of light bright enough to be seen by the naked eye - if anyone had known where to look. (By naked eye standards it was just on the edge of visibility, so it's doubtful anyone noticed it, even if they did see it. Still, the idea that you could see something with your naked eye that started 7 billion light years away is incredible. You can routinely pick out the Andromeda Galaxy with your naked eye, but that's a mere 2.5 million light years from us and at that, what we are seeing is the combined glow of several hundred billion stars. Reporting this today, the New York Times notes:

The visible glow from this burst, said Neil Gehrels of NASA’s Goddard Space Flight Center, was 10 million times as bright as a supernova at that same distance. The universe is some 14 billion years old, which means that the news of this cataclysm has been on its way to us for half the age of the universe. Whatever stars went to their grave then have been dead since before the Sun and Earth were born.