  Extracting stellar fundamental parameters from SPectro-Interferometric (SPI)
data requires reliable estimates of observables and with robust uncertainties
(visibility, triple product, phase closure). A number of fine calibration
procedures is necessary throughout the reduction process. Testing departures
from centro-symmetry of brightness distributions is a useful complement.
Developing a set of automatic routines, called SPIDAST (made available to the
community) to reduce, calibrate and interpret raw data sets of instantaneous
spectro-interferograms at the spectral channel level, we complement (and in
some respects improve) the ones contained in the amdlib Data Reduction
Software. Our new software SPIDAST is designed to work in an automatic mode,
free from subjective choices, while being versatile enough to suit various
processing strategies. SPIDAST performs the following automated operations:
weighting of non-aberrant SPI data (visibility, triple product), fine spectral
calibration (sub-pixel level), accurate and robust determinations of stellar
diameters for calibrator sources (and their uncertainties as well), correction
for the degradations of the interferometer response in visibility and triple
product, calculation of the Centro-Symmetry Parameter (CSP) from the calibrated
triple product, fit of parametric chromatic models on SPI observables, to
extract model parameters. SPIDAST is currently applied to the scientific study
of 18 cool giant and supergiant stars, observed with the VLTI/AMBER facility at
medium resolution in the K band. Because part of their calibrators have no
diameter in the current catalogs, SPIDAST provides new determinations of the
angular diameters of all calibrators. Comparison of SPIDAST final calibrated
observables with amdlib determinations shows good agreement, under good and
poor seeing conditions.
