The Robert C. Byrd Green Bank Telescpoe is located in the national radio quiet zone in West Virginia. It is the largest steerable instrument in the world, with a dish 300 feet in diameter and height 485 feet above the ground. I've used this telescope to observe 21cm radiation from neutral hydrogen in nearby galaxies hosting an active galactic nucleus (AGN).
An AGN is a supermassive black hole actively feeding on nearby material. The accretion disk houses the gas that is orbiting around and falling into the black hole. Further away from the black hole are thick clouds moving at extremely fast speeds, and this environment is referred to as the broad line region. I measure distances to galaxies which host a supermassive black hole such as this, and also use the behavior of these environments to measure black hole masses.