We present our numerical simulation approach for the End-to-End (E2E) model applied to various astronomical spectrographs, such as SOXS (ESO-NTT), CUBES (ESO-VLT), and ANDES (ESO-ELT), covering multiple wavelength regions. The E2E model aim at simulating the expected astronomical observations starting from the radiation of the scientific sources (or calibration sources) up to the raw-frame data produced by the detectors. The comprehensive description includes E2E architecture, computational models, and tools for rendering the simulated frames. Collaboration with Data Reduction Software (DRS) teams is discussed, along with efforts to meet instrument requirements. The contribution to the cross-correlation algorithm for the Active Flexure Compensation (AFC) system of CUBES is detailed.
NIRPS is a fiber-fed AO nIR spectrograph working simultaneously with HARPS at the La Silla-ESO 3.6m telescope. The cryogenic spectrograph operating at 75K employs a cross-dispersed echelle grating (R4), covering a wavelength range of 0.98-1.80 microns in a single image using a Teledyne Hawaii-4RG infrared detector. In early 2022, the NIRPS spectrograph was transported to Chile by plane with all the optical elements mechanically attached to the optical bench inside the vaccum vessel. To ensure the safety of the spectrograph, dedicated work was performed on the shipping crate design, which could survive up to 7g shocks. In La Silla, the vacuum vessel was re-integrated on its support structure and the spectrograph alignment was verified with the H4RG and the injection module. Given the optical design, the alignment phase was performed using a metrology arm and a few optical tests, which minimize the time required for this critical phase. From the validation/technical phase results, two major modifications were required. Firstly, the original grating element was replaced by a new etched crystalline silicon component made by the Fraunhofer Institute for Applied Optics and Precision Engineering. A novel technique was developed to verify the alignment at a warm temperature with the H4RG detector. Secondly, a thermal enclosure was added around the vacuum vessel to optimize thermal stability. Since then, the long-term thermal stability has been better than 0.2mK over 20 days. In this paper, we will review the final spectrograph performances, prior to shipping, and describe the novel techniques developed to minimize shipping costs, AITV phase duration, and grating replacement at the observatory. Additionally, we will discuss the thermal enclosure design to achieve the sub-mK thermal stability.
The Near-InfraRed Planet Searcher or NIRPS is a precision radial velocity spectrograph developed through collaborative efforts among laboratories in Switzerland, Canada, Brazil, France, Portugal and Spain. NIRPS extends to the 0.98-1.8 μm domain of the pioneering HARPS instrument at the La Silla 3.6-m telescope in Chile and it has achieved unparalleled precision, measuring stellar radial velocities in the infrared with accuracy better than 1 m/s. NIRPS can be used either standalone, or simultaneously with HARPS. Commissioned in late 2022 and early 2023, NIRPS embarked on a 5-year Guaranteed Time Observation (GTO) program in April 2023, spanning 720 observing nights. This program focuses on planetary systems around M dwarfs, encompassing both the immediate solar vicinity and transit follow-ups, alongside transit and emission spectroscopy observations. We highlight NIRPS’s current performances and the insights gained during its deployment at the telescope. The lessons learned and successes achieved contribute to the ongoing advancement of precision radial velocity measurements and high spectral fidelity, further solidifying NIRPS’ role in the forefront of the field of exoplanets.
We present the Exposure Time Calculator (ETC) in development for ANDES, the high-resolution optical-infrared spectrograph for the Extremely Large Telescope. The ETC is a tool to predict the performances of the instrument for different parameters and environmental conditions. For these reasons, it is extremely useful in several stages of the project, from the design of the instrument to the preparation of the observations.
NIRPS (Near Infra-Red Planet Searcher) is an AO-assisted and fiber-fed spectrograph for high precision radial velocity measurements in the YJH-bands. NIRPS also has the specificity to be an SCAO assisted instrument, enabling the use of few-mode fibers for the first time. This choice offers an excellent trade-off by allowing to design a compact cryogenic spectrograph, while maintaining a high coupling efficiency under bad seeing conditions and for faint stars. The main drawback resides in a much more important modal-noise, a problem that has to be tackled for allowing 1m/s precision radial velocity measurements. In this paper, we present the NIRPS Front-End: an overview of its design (opto-mechanics, control), its performance on-sky, as well as a few lessons learned along the way.
KEYWORDS: Spectrographs, Telescopes, Lanthanum, Planets, Spectroscopes, Exoplanets, Aerospace engineering, Space operations, James Webb Space Telescope
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.
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