Which is the nearest black hole?

Answer 1

From Hubbelsite:
"The nearest one is some 1,600 light-years from Earth."

From "Ask an Astrophysicist":
"It is actually difficult to determine the distance to black holes, but a nearby object believed to be a black hole from observations of strong X-ray emission is Cygnus X-1, located about 8000 light years away. Cyg X-1 is an ordinary star that is believed to be orbiting a black hole."

From National Radio Astronomy Observatory:
"Scientists have discovered the closest black hole yet, a mere 1,600 light years from Earth. Its discovery was heralded by four of the most dramatic rapid X-ray intensity changes ever seen from one star.

Astronomers from the Massachusetts Institute of Technology (MIT) and the National Science Foundation's National Radio Astronomy Observatory (NRAO) announced their findings at the American Astronomical Society's meeting in Atlanta.

The black hole in the constellation Sagittarius, along with a normal star dubbed V4641 Sgr, form a violent system that briefly flooded part of our Milky Way Galaxy with X-rays and ejected subatomic particles moving at nearly the speed of light one day last September. At the peak of its X-ray output, V4641 Sgr was the brightest X-ray emitter in the sky."