De-biasing interferometric visibilities in VLTI-AMBER data of low SNR observations
Résumé
Aims. We have found that the interferometric visibilities of VLTI-AMBER observations, extracted via the standard reduction package, are significantly biased when faint targets are concerned. The visibility biases derive from a time variable fringing effect (correlated noise) appearing on the detector. Methods: We have developed a method to correct this bias that consists in a subtraction of the extra power caused by such correlated noise, so that the real power spectrum at the spatial frequencies of the fringing artifact can be restored. Results: This pre-processing procedure is implemented in a software program called AMDC, available to the community, which is to be run before the standard reduction package. Results obtained on simulated and real observations are presented and discussed. Based on VLTI-AMBER observations.