NEAR INFRARED CAMERA SPECTROMETER (NICS) ================================= Instrument Overview =================== NICS (Near Infrared Camera Spectrometer) is the TNG infrared (0.9-2.5 micron) multimode instrument which is based on a HgCdTe Hawaii 1024x1024 array. Its observing capabilities include imaging (4.2' x 4.2' f.o.v.), high-throughput low resolution spectroscopy (RS=50-500), medium resolution spectoscopy (max-R=2500), imaging polarimetry, spectropolarimetry and, when coupled to the adaptive optics module, nearly diffraction limited imaging. Long slit spectroscopic observations are performed by inserting a slit at the entrance focal plane and a disperser (grism or prism) in the collimated beam. The table here lists the slits available in NICS which, thanks to the refurbishment works of Feb-Mar 2003, have now a very stable and repeatable positioning. All spectroscopic modes make use of the LF camera with a scale of 0.25 arcsec/pixel. NICS slits Name Width Length 0.5 0.5' = 2 pix 4' 0.75 0.75' = 3 pix 4' 1.0 1.0' = 4 pix 4' 1.5 1.5' = 6 pix 4' 2.0 2.0' = 8 pix 4' The instrument is equipped with one prism and a number of grism dispersers whose main characteristics are listed in the table below. Note that the grisms have a fairly constant dispersion (angstroms/pix) throughout the spectrum and, therefore, their resolving power increases going towards the red. The Amici prism, on the contrary, delivers a spectrum with a quasi-constant resolving power and, therefore, its dispersion varies by more than a factor of 3 over its spectral range. All the low resolution dispersers can be used in combination with the grey filters to take spectra of very bright objects which would otherwise saturate the array. NICS dispersers Name wl-range (micron) disp. (angstrom/pix) Res. power with 1' slit Low resolution Amici 0.8-2.5 30-100 50 IJ 0.9-1.45 5.5 500 JH 1.15-1.75 6.6 500 JK' 1.15-2.23 11.6 350 HK 1.40-2.50 11.2 500 Medium resolution 1mic 0.96-1.09 2.0 1250 Js 1.17-1.33 2.5 1200 J 1.12-1.40 2.5 1200 H 1.48-1.78 3.5 1150 KB 1.95-2.34 4.3 1250 Reference: Baffa, C. and 16 colleagues, NICS: The TNG near-infrared camera spectrometer, Astronomy and Astrophysics, 378, 722-728, 2001. References ========== Baffa, C. and 16 colleagues, NICS: The TNG near-infrared camera spectrometer, Astronomy and Astrophysics, 378, 722-728, 2001.