NIRPS is a near-infrared (YJH bands), fiber-fed, high-resolution precision radial velocity (pRV) spectrograph currently under construction for deployment at the ESO 3.6-m telescope in La Silla, Chile. Through the use of a dichroic, NIRPS will be operated simultaneously with the optical HARPS pRV spectrograph and will be used to conduct ambitious planet-search and characterization surveys through a 720-night of guaranteed time allocation. NIRPS aims at detecting and characterizing Earth-like planets in the habitable zone of low-mass dwarfs and obtain high-accuracy transit spectroscopy of exoplanets. Here we present a summary of the full performances obtained in laboratory tests conducted at Université Laval (Canada), and the first results of the on-going on-sky commissioning of the front-end. Science operations of NIRPS is expected to start in late-2020, enabling significant synergies with major space and ground instruments such as the JWST, TESS, ALMA, PLATO and the ELT.
We present our development of the Multi-Object Adaptive Optics (MOAO) system for the Gemini Infra-Red Multi-Object Spectrograph (GIRMOS). The GIRMOS MOAO system consists of four identical arms patrolling over a large field-ofregard (2 arcmin) and able to deliver an image quality close to the diffraction-limit in the near-infrared. The AO system of GIRMOS will performed MOAO correction on top of the wavefront delivered by the Gemini North AO (GNAO) system. We are currently prototyping one arm in the laboratory in order to validate the simulated performances and characterize the hardware as well as different MOAO control strategies. GIRMOS MOAO is a complex AO system and a complete lab characterization would require a full GNAO simulator with a pick-off system and multiple wavefront sensors (WFS), light sources, etc. To circumvent the cost and complexity of such a system we are using a spatial light modulator (SLM) allowing the generation of residual turbulences in specific directions in the field without the need of pick-off system. Coupled with a numerical end-to-end model of the system, our bench is focused on open-loop control rather than tomography. In this paper, we review the GIRMOS MOAO preliminary design of the system, the baseline performances and the status of the testbed.
GIRMOS is a multi-object adaptive optics spectrograph in the near-infrared currently being designed for the Gemini North telescope. It will allow to observe with high-quality adaptive optics correction multiple targets selected from a large field. To increase the efficiency of the nightly observations, it is important to provide a feedback in real time to operators and observers on the quality of the point-spread function, using intuitive metrics such as the full width at half maximum, the Strehl ratio and the encircled energy. We present a set of simple analytical expressions derived from other works that use the measurement of the wavefront residuals. We then compare the results to an end-to-end AO simulation of GIRMOS. We show that this approach works well with the estimation of the full width at half maximum and the Strehl ratio, while it is less successful with the encircled energy.
The Gemini Infra-Red Multi-Object Spectrograph (GIRMOS) is a four-arm, Multi-Object Adaptive Optics (MOAO) IFU spectrograph being built for Gemini (commissioning in 2024). GIRMOS is being planned to interface with the new Gemini-North Adaptive Optics (GNAO) system, and is base lined with a requirement of 50% EE within a 0.100 spaxel at H-band. We present a design and forecast the error budget and performance of GIRMOS-MOAO working behind GNAO. The MOAO system will patrol the 20 field of regard of GNAO, utilizing closed loop GLAO or MCAO for lower order correction. GIRMOS MOAA will perform tomographic reconstruction of the turbulence using the GNAO WFS, and utilize order 16x16 actuator DMs operating in open loop to perform an additional correction from the Pseudo Open Loop (POL) slopes, achieving close to diffraction limited performance from the combined GNAO+MOAO correction. This high performance AO spectrograph will have the broadest impact in the study of the formation and evolution of galaxies, but will also have broad reach in fields such as star and planet formation within our Milky Way and supermassive black holes in nearby galaxies.
NIRPS (Near Infra Red Planet Searcher) is a new ultra-stable infrared ( YJH) fiber-fed spectrograph that will be installed on ESO’s 3.6-m telescope in La Silla, Chile. Aiming at achieving a precision of 1 m/s, NIRPS is designed to find rocky planets orbiting M dwarfs, and will operate together with HARPS (High Accuracy Radial velocity Planet Searcher). In this paper we describe NIRPS science cases, present its main technical characteristics and its development status.
Since 1st light in 2002, HARPS has been setting the standard in the exo-planet detection by radial velocity (RV) measurements. Based on this experience, our consortium is developing a high accuracy near-infrared RV spectrograph covering YJH bands to detect and characterize low-mass planets in the habitable zone of M dwarfs. It will allow RV measurements at the 1-m/s level and will look for habitable planets around M- type stars by following up the candidates found by the upcoming space missions TESS, CHEOPS and later PLATO. NIRPS and HARPS, working simultaneously on the ESO 3.6m are bound to become a single powerful high-resolution, high-fidelity spectrograph covering from 0.4 to 1.8 micron. NIRPS will complement HARPS in validating earth-like planets found around G and K-type stars whose signal is at the same order of magnitude than the stellar noise. Because at equal resolving power the overall dimensions of a spectrograph vary linearly with the input beam étendue, spectrograph designed for seeing-limited observations are large and expensive. NIRPS will use a high order adaptive optics system to couple the starlight into a fiber corresponding to 0.4” on the sky as efficiently or better than HARPS or ESPRESSO couple the light 0.9” fiber. This allows the spectrograph to be very compact, more thermally stable and less costly. Using a custom tan(θ)=4 dispersion grating in combination with a start-of-the-art Hawaii4RG detector makes NIRPS very efficient with complete coverage of the YJH bands at 110’000 resolution. NIRPS works in a regime that is in-between the usual multi-mode (MM) where 1000’s of modes propagates in the fiber and the single mode well suited for perfect optical systems. This regime called few-modes regime is prone to modal noise- Results from a significant R and D effort made to characterize and circumvent the modal noise show that this contribution to the performance budget shall not preclude the RV performance to be achieved.
Radial velocity instruments require high spectral resolution and extreme thermo-mechanical stability, even more difficult to achieve in near-infra red (NIR) where the spectrograph has to be cooled down. For a seeing-limited spectrograph, the price of high spectral resolution is an increased instrument volume, proportional to the diameter of the primary mirror. A way to control the size, cost, and stability of radial velocity spectrographs is to reduce the beam optical etendue thanks to an Adaptive Optics (AO) system. While AO has revolutionized the field of high angular resolution and high contrast imaging during the last 20 years, it has not yet been (successfully) used as a way to control spectrographs size, especially in the field of radial velocities.
In this work we present the AO module of the future NIRPS spectrograph for the ESO 3.6 m telescope, that will be feed with multi-mode fibers. We converge to an AO system using a Shack-Hartmann wavefront sensor with 14x14 subapertures, able to feed 50% of the energy into a 0.4" fiber in the range of 0.98 to 1.8 μm for M-type stars as faint as I=12.