Aims:We present a comprehensive study that applies the Fourier transform to a sample of O and early B-type stars (either dwarfs, giants, or supergiants) to determine their projected rotational velocities. We then compare them with previous values obtained with other methods and seek evidence of extra broadening in the spectral lines Methods: The

OSIRIS, the main optical (360-1000nm) 1st-generation instrument for GTC, is being integrated. Except for some grisms and filters, all main optical components are finished and being characterized. Complementing laboratory data with semi-empirical estimations, the current OSIRIS efficiency is summarized.

We present techniques for the estimation of stellar atmospheric parameters (T_eff, log~g, [Fe/H]) for stars from the SDSS/SEGUE survey. The atmospheric parameters are derived from the observed medium-resolution (R = 2000) stellar spectra using non-linear regression models trained either on (1) pre-classified observed data or (2) synthetic stellar

EMIR, currently entering into its fabrication and AIV phase, will be one of the first common user instruments for the GTC, the 10 meter telescope under construction by GRANTECAN at the Roque de los Muchachos Observatory (Canary Islands, Spain). EMIR is being built by a Consortium of Spanish and French institutes led by the Instituto de Astrofísica

Elmer is a multi-purpose instrument for the GTC designed for both Imaging and Spectroscopy in the visible range (365 nm-1000 nm). Spectroscopy in Elmer is done by using 2 prisms, 2 grisms, and 6 VPHs as dispersive elements, providing resolving powers of 200, 1000, and 2500, respectively over the whole wavelength range for a 0.6'' slit width.

Elmer is a multi-purpose instrument for the GTC designed for both Imaging and Spectroscopy in the visible range (365-1000 nm). Imaging will be done in a 4.2' circular Field of View (FOV), through standard SDSS broad band filters (g', r', I', and z') as well as narrow band filters (Hα broad, Hα narrow, Hβ, [OI], [OII], [OIII], [SII] broad, and [SII]