The photoabsorption spectra of single-shell icosahedral fullerenes are investigated in the region of the strongest diffuse interstellar band at 4430 Å. According to Hückel and Pariser-Parr-Pople models, several fullerenes (C80, C240, C320, and C540) present transitions in the vicinity of this band. The same semiempirical models also predict a high

FRIDA (inFRrared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) is being designed as a diffraction limited instrument with broad and narrow band imaging and integral field spectroscopy capabilities to operate in the wavelength range 0.9 - 2.5 μm. FRIDA is a collaborative project between the main GTC partners

FRIDA (inFRrared Imager and Dissector for the Adaptive optics system of the Gran Telescopio Canarias) is being designed as a diffraction limited instrument with broad and narrow band imaging and integral field spectroscopy capabilities to operate in the wavelength range 0.9 - 2.5 μm. FRIDA is a collaborative project between the main GTC partners

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