The Nanogravity Experiment and the Nanohirts

The nanograv experiment is sensitive to gravitationally frequencies that are between one and 100 nanohirts. The signal that we're looking for is so small that these timing changes are about 100 nanoseconds over a decade. So just as an example, a supermassive black hole pair that are orbiting each other with a period of 30 years would have a gravitationally frequency of one nanohirt. Depending on the exact frequency, that'll change what the wavelength is. But we're looking at wavelengths of a light year to a few light years.