Calibrating optical/IR interferometry visibility data

By construction, optical (and near-infrared) interferometers typically have resolutions designed to resolve stellar and circumstellar features; such resolution is manifested as fringe contrast (or visibility) reduction for the resolved source. These same interferometers also experience visibility reductions due to instrumental and environmental limitations, so a careful data calibration is required to accurately differentiate astrophysical and instrumental effects. This contribution discusses the basic techniques for and sources of errors in visibility data calibration, and selection strategies for sources used to calibrate the interferometer response.