CRIRES is a cryogenic high-resolution pre-dispersed infrared echelle spectrograph, developed by ESO. It provides a resolving power of up to 100,000 between 0.95 and 5.38 μm. It was offered for the first time in P79.

Note that CRIRES was removed in July 2014 for an upgrade. It will not be available from P94 onwards. It is expected that CRIRES plus will be comissioned starting in October 2019 with the aim to offer the instrument from 1st October 2020 (see the CRIRES plus website here for the latest date). A link to the messenger article describing CRIRES plus is available at http://www.eso.org/public/announcements/ann14053/


CRIRES is located at the Nasmyth A focus of UT1. Functionally, it can be divided into four units:

  • The fore-optics part provides the field rotation, cold pupil and field stops, adaptive optics and slit viewing.
  • The prism pre-disperser isolates one echelle order and minimizes the total amount of light entering into the high-resolution section.
  • The high-resolution section comprises the collimator, the echelle which is tilt-tuned for wavelength selection, the camera providing the 0."086/pixel scale, and the detectors.
  • The calibration unit outside the cryogenic environment contains light sources for flux/wavelength calibration and detector flat-fielding.

The spectrograph is housed in a vacuum vessel, with its optics cooled to ~65K and the detectors to ~25K. The main characteristics of CRIRES are summarized in Table 1.

Table 1. Main characteristics of CRIRES
Wavelength range
Resolving power (2 pixels)
Slit width
fixed slits with width 0.0, 0.2 and 0.4 arcsec (since intervention in October 2011, before that 0.05" to 3.0")
Slit length
40 arcsec
Pixel size (spatial direction)
0.086 arcsec
Adaptive optics feed
60 actuators curvature sensing system
Calibration system
Integrating sphere + cont.+ line lamps + gas-cells (N20, CO, soon OCS)
Slit viewer
Aladdin array, J,H,K and 2 neutraldensity H filters, 0.047 arcsec/pix
ZnSe prism
Echelle grating
40x20cm, 31.6 lines/mm, 63.5 deg. blaze
Detector array
4096x512 pixels using 4 Aladdin arrays, with inter-detector gaps of nominally 283 pixels

Thanks to CRIRES, new phenomena and objects are now available forspectroscopic studies. Table 2 presents a list of science objectives.

Table 2: Science Objectives


Extra-Solar Planets

Radial velocities studies

Direct spectroscopic detection and characterization of CO, CH4.

Solar System

Chemistry, physical conditions, velocity fields, structure

Giant planets, Titan

H3+, CH4, NH3, CH3D, AsH3, H2O,C2H2,C2H6, PH3, CH3, NH3, HCN,C2H2, C2H6, PH3, CH3, NH3, HCN

Terrestrial planets

Mapping of CO depletion in the atmosphere of Mars.


spatial, time mapping of volcanic activity (SO2)


search for tenous CO, CH4 atmosphere


H2O abundance, temperature, velocities,minor species.


Stellar evolution, nucleosynthesis (OB, AGB stars, cluster redgiants, cool MS, C & S stars in galaxy, S/LMC, nearbyglaxies), CNO isotopic abundances unique in IR.

Stellar mass: atomic, molecular lines from secondaries

Stellar winds, mass loss of OB, WR, AGB stars in galaxy andSMC, LMC based on CO,SiO,C2H2, HCN

Atmospheric structure & oscillations in cool stars

Magnetic fields

Star Formation Regions/ISM

Accretion, outflow from embedded YSOs

ISM chemistry, cloud structure using H3+, H2O, CH4, C2H2, NH3



Velocity structure of BLR, NLR, CLR & molecular clouds, Hrecombination, [FeII], [SiIV], H2 lines suffering low dustextinction