A powerful gamma ray burst detected March 19th by NASA's Swift satellite has shattered the record for the most distant object that could be seen with the naked eye.
One summer when I was in undergrad I did astrophysics research, specifically, working with data on high-energy particles emitted by black hole candidates. A high energy particle triggers a shower of lesser-energy particles when it hits the atmosphere and interacts with the particles that make up the atmosphere, and it all cascades farther and farther (if energetic enough) until the shower eventually propagates down to the ground. In general, the higher the energy of the incoming particle, the higher the energy of the particles in the shower hitting your detector on the ground. Plus, the more atmosphere the shower is propagating through, the more energy is used up.
So, the highest energy particles that come in almost horizontally have cascaded through the most atmosphere to get to you, and thus were really REALLY high energy before they started, and thus might be from a black hole.
I worked on processing those data measurements calculating the incident angle of the initial particle, to then determine if it was from a black hole candidate. Fun stuff. I love science.