The CRIRES upgrade project (CRIRES+) will improve the performance and observing efficiency of the successful adaptive optics (AO) assisted CRIRES instrument. CRIRES was in operation from 2006 to 2014 at the 8m UT1 (Unit Telescope) of the Very Large Telescope (VLT, Cerro Paranal, Chile) observatory accessing a parameter space (wavelength range and spectral resolution) largely uncharted back then.
CRIRES+ will be commissioned in summer 2018 at UT3 of the VLT. It will provide a spectral resolution of R=50.000 or 100.000 in an accessible wavelength range of 0.95 – 5.3 μm (YJHKLM bands). For each band there is a separate, performance optimized reflection grating as the cross dispersing element. The slit length of 10 arcsec will provide, in combination with the new focal plane array of three HAWAII 2RG detectors, cross-dispersed (7 – 9 orders simultaneous) echelle spectra. In total, the observing efficiency will be improved by a factor of 10 comparing CRIRES+ and CRIRES. Furthermore, the upgraded instrument will be equipped with a number of novel wavelength calibration units, including a gas absorption cell optimized for use in K band and an etalon system. A spectro-polarimetric unit will allow the recording of circular and linear polarized spectra. The new metrology system will ensure a very high system stability and repeatability. Last but not least the upgrade will be supported by dedicated data reduction software allowing the community to take full advantage of the new capabilities.
The full system is being integrated at ESO and system testing has commenced. Acceptance of the instrument in Europe (PAE) is scheduled for the second quarter of 2018. Commissioning at the VLT observatory will start mid 2018. This article gives an overview of the final configuration of the instrument. The instrument will be available to the astronomic community from Spring 2019 with a call for proposals in October 2018.
CRIRES+ is the new high-resolution NIR echelle spectrograph intended to be operated at the platform B of VLT Unit telescope UT3. It will cover from Y to M bands (0.95-5.3um) with a spectral resolution of R = 50000 or R=100000. The main scientific goals are the search of super-Earths in the habitable zone of low-mass stars, the characterisation of transiting planets atmosphere and the study of the origin and evolution of stellar magnetic fields. Based on the heritage of the old adaptive optics (AO) assisted VLT instrument CRIRES, the new spectrograph will present improved optical layout, a new detector system and a new calibration unit providing optimal performances in terms of simultaneous wavelength coverage and radial velocity accuracy (a few m/s). The total observing efficiency will be enhanced by a factor of 10 with respect to CRIRES. An innovative spectro-polarimetry mode will be also offered and a new metrology system will ensure very high system stability and repeatability. Fiinally, the CRIRES+ project will also provide the community with a new data reduction software (DRS) package. CRIRES+ is currently at the initial phase of its Preliminary Acceptance in Europe (PAE) and it will be commissioned early in 2019 at VLT. This work outlines the main results obtained during the initial phase of the full system test at ESO HQ Garching.