AMBER data reduction

This course describes the data reduction process of the AMBER instrument, the three beam-recombiner of the very large telescope interferometer (VLTI). In body of this paper, we develop its principles from a theoretical point of view and we illustrate the main points with examples taken from the practical AMBER data reduction session given during school. The detailed practical application making use of the ESO gasgano tool is then presented. In this lecture, we particularly emphasize what the AMBER data reduction process is (i) a fit of the interferogram in the detector plane, (ii) using an a priori calibration of the instrument, where (iii) the complex visibility of the source is estimated from a least-square determination of a linear inverse problem, and where (iv) the derived AMBER observables are the squared visibility, the closure phase, and the spectral differential phase.