IRCS Overview

IRCS (Infrared Camera and Spectrograph) is a facility instrument of the Subaru Telescope, providing high-resolution imaging and spectroscopy with the adaptive optics (AO) and tip-tilt at 0.9 - 5.5 $\mu$m.

IRCS consists of two sections (Figure 20). One is a near-infrared camera with two available pixel scales: 0.058 and 0.023 $^{\prime\prime}$/pix. The camera section also serves as an infrared slit-viewer for echelle spectroscopy. The infrared slit-viewer is very useful to locate slit positions. The camera section also provides low spectral resolution grism spectroscopy in the near infrared.

The other is a cross-dispersed echelle spectrograph that provides high velocity resolutions (15$-$60 km s$^{-1}$). The echelle section has a pixel scale of 0.060 $^{\prime\prime}$/pix along the slit length, allowing us to study detailed velocity structure of $\sim$10 AU scale around YSOs in Taurus molecular cloud. The echelle part covers the entire $J$-, $H$-, or $K$-band with only one or two echelle configurations (Table 1). The slit length is variable from 3$.^{''}$8 to 10$.^{''}$0.

Each section is equipped with a Raytheon 1024 $\times$ 1024 InSb IR array with an Aladdin multiplexer.

Table 1: IRCS echelle configurations.

Band	Coverage ($\mu$m)	Spectral resolution (0$.^{''}$15 slit)	Dispersion (Å/pixel)	Slit length (arcsec)	No. of exposures
$Iz$(1)	0.92 - 1.01	$\sim$20000		3.8	1
$zJ$	1.03 - 1.18	19000 - 22600	0.25 - 0.28	3.8	1
$J$	1.18 - 1.38	19000 - 22600	0.28 - 0.33	3.8	1
$H$	1.49 - 1.83	18800 - 22900	0.36 - 0.44	5.6	2
$K$	1.90 - 2.49	18300 - 22300	0.46 - 0.62	5.6	2
$L$	2.80 - 4.20	17300 - 25100	0.67 - 1.06	10.0	6
$M$	4.41 - 5.34	16800 - 26300	1.16 - 1.30	10.0	4

Figure 20: Layout of (a) the fore-optics and camera sections and (b) the spectrograph section (Tokunaga et al., 1998).