NAHUAL:: a near-infrared high-resolution spectrograph for the GTC optimized for studies of ultracool dwarfs

We present the status of an ongoing study for a high-resolution near-infrared echelle spectrograph for the 10.4-m GTC (Gran Telescopio de Canarias) which will soon start operating at the Observatorio del Roque de los Muchachos on the island of La Palma. The main science driver of this instrument, which we have baptized NAH-UAL, is to carry out a high precision radial velocity survey of exoplanets around ultracool dwarfs. NAHUAL is being especially designed to achieve the highest possible accuracy for radial velocity measurements. The goal is to reach an accuracy of a few m/s. It is thus required that the instrument is cross-dispersed and that it covers simultaneously a wide wavelength range. Absorption cells will be placed in front of the slit which will allow a simultaneous self-reference similar to an iodine-cell in the optical regime. It is planned to place the instrument at one of the Nasmyth platform of the GTC behind the Adaptive Optics system. Our current design reaches a maximum spectral resolution of lambda/Delta lambda=50000 with a slit width of 0.175 arcsec, and gives nearly complete spectral coverage from 900 to 2400 nm.