The Uncertainty of Distance Measurements

Using something called a maser they can see these blobs of water orbiting a black hole in a distant galaxy. By measuring that acceleration and doing like a little bit of like Kepler's laws you can figure out what is the radius of its orbit around this black hole. But it hasn't yet provided a measurement that compares with the uncertainty of the other measurements. It's one people are excited about because it's very independent from the other measurements not affected by dust at all.