LonGSp: The Longslit Infrared Spectrometer of Gornergrat

LonGSp is a near-infrared grating spectrometer, designed for the 1.5 m Italian Infrared Telescope T.I.R.GO. (Telescopio Infrarosso del Gornergrat) situated at Gornergrat (Switzerland).

The development of this instrument was part of a project oriented to equip the IR italian telescope with a new series of instruments based on the Rockwell HgTeCd NICMOS3 arrays. Whitin the framework of this project, result of a joint effort of the Arcetri Observatory, the Department of Astronomy of the University of Florence and the National Research Council of Italy (CNR-CAISMI), indeed was also built the Arcetri Near Infrared Camera ArNICa.

The spectrometer is equipped with cooled reflective (except the field lens) optics and a grating arranged in Littrow configuration, the detector is an "engineering grade" Rockwell NICMOS3 array (256x256 pixels of 40 µm). The sky-projected pixel size along the slit is 1.73" and the maximum slit length is about 70., this means that only a 40 pixels stripe of the array is used. The accessible spectral range is 0.95-2.5µm with a dispersion, at the first order, of about 11.5 Angstrom/pixel.

Read-out and control electonics are the same of ArNICa, based on the IRL System 2 developed by Infrared Laboratories (Tucson - AZ), with the necessary alteration to control slits and grating and for handling spectroscopic data.

The spectrometer is remotely controlled by a 486 PC, connected to the array detector control electronics via a fiber-optics link and a custom made PC board interface. A C-language package, running under MS-DOS on the 486 PC, acquires and stores the frames, and controls the timing of the array and the other parametrs of measures. Data are stored in FITS format on the PC hard disk.

Test observations at the telescope started in 1994. and since January 1996 LonGSp is offered to T.I.R.GO. users and employed in several galactic and extragalactic programs.

More informations on the instrument can be obtained in the following subsections:

• A general description
• Characterization test results
• User’s handbook
• Observations, Data handling and reduction
• Publications about LonGSp

For comments or more informations about the instument please e-mail to: longsp@arcetri.astro.it

Last update 28 January 2000

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