  This work describes a procedure to derive several fundamental parameters such
as the effective temperature, surface gravity, equatorial rotational velocity
and microturbulent velocity. In this work, we have written a numerical
procedure in Python which finds the best fit between a grid of synthetic
spectra and the observed spectra by minimizing a standard chi-square. LTE model
atmospheres were calculated using the ATLAS9 code and were used as inputs to
the spectrum synthesis code SYNSPEC48 in order to compute a large grid of
synthetic Balmer line profiles. This new procedure has been applied to a large
number of new observations (GIRAFFE spectra) of B and A stars members of the
young open cluster NGC3293. These observations are part of the GAIA ESO Survey.
Takeda's procedure was also used to derive rotational velocities and
microturbulent velocities. The results have been compared to previous
determinations by other authors and are found to agree with them. As a first
result, we concluded that using this procedure, an accuracy of +-200 K could be
achieved in effective temperature and +-0.2 dex in surface gravities.
