Time-Lapse Look at Microlensing From a Black Hole

This is a time-lapse of a set of four Hubble Space Telescope photos that capture the gravitational effects of an invisible black hole drifting through our galaxy. Because a black hole doesn't emit or reflect light, it cannot be directly observed. But its unique thumbprint on the fabric of space can be measured by the way it warps the light of a background star, an effect called gravitational microlensing. The background star momentarily brightened, as first captured by Hubble beginning in August, 2011, and then faded back to normal brightness, as the foreground black hole drifted by. Finding the telltale signature of an isolated black hole is a needle-in-haystack search for Hubble astronomers.

Credit:

Science: NASA, ESA, Kailash Sahu (STScI)
Animation: Joseph DePasquale (STScI)

[mikel]

There are no Black Holes anywhere in the Universe.
You don't understand correctly what you "observe".