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The High Resolution Spectrograph of TNG: a Status Report
BibTeX
@MISC{Gratton_thehigh,
author = {R. G. Gratton and A. Cava. Zza and R. U. Claudi and M. Rebeschini and G. Bonanno and P. Bruno and A. Cali and S. Scuderi and R. Cosentino and S. Desidera},
title = {The High Resolution Spectrograph of TNG: a Status Report},
year = {}
}
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Abstract
The high resolution spectrograph of the TNG (SARG) was projected to cover a spectral range from A=O.37 up to 0.9 pm, with resolution ranging from R=l9,000 up to R=144,000. The dispersing element of the spectrograph is an R4 echelle grating in Quasi-Littrow mode; the beam size is 100 mm giving an RS product of RS=46,000 at order centre. Both single object and long slit (up to 30 arcsec) observing modes are possible: in the first case cross-dispersion is provided by means of a selection of four grisms; interference filters are used for the long slit mode. A dioptric camera images the cross dispersed spectra onto a mosaic of two 2048 x 4096 EEV CCDs (pixel size: 13.5 pm) allowing complete spectral coverage at all resolving power for A.<O.8.tm. Confocal image slicers are foreseen for observations at R 76,000; an absorbing cell for accurate radial velocities is also considered. SARG will be rigidly fixed to one of the arms of the TNG fork by means of an optical table and a special thermally insulating enclosure (temperature of all spectrograph components will be kept constant at a preset value by a distributed active thermal control system). All functions are motorized in order to allow very stable performances and full remote control. The architecture of SARG controls will be constructed around a VME crate linked to the TNG LAN and the instrument Workstation B by a fiber optic link.
Keyphrases
high resolution spectrograph status report beam size confocal image slicer r product optical table sarg control spectrograph component vme crate stable performance first case cross-dispersion tng fork single object preset value fiber optic link interference filter pixel size long slit mode order centre long slit absorbing cell instrument workstation insulating enclosure accurate radial velocity r4 echelle quasi-littrow mode tng lan complete spectral coverage spectral range distributed active thermal control system dioptric camera full remote control eev ccds
