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.
VROOMM is an optical (360nm - 930 nm) high-resolution échelle spectrograph currently in its design phase for the 1.6-meter telescope of the Observatoire du Mont-Mégantic (OMM) in Québec, Canada. Specifically designed for precision radial velocity (RV) measurements of relatively faint stars, the instrument features a 4K photon-counting EMCCD, octagonal fibers, and a double scrambler, all housed in a thermally stabilized vacuum cryostat. Designed for a resolution exceeding 80 000, the spectrograph aims to provide RV measurements with precision tailored for specific cases. The first scenario involves using the EMCCD like a normal CCD without electron amplification, enabling follow-up observations of terrestrial planets, super-Earths, and mini-Neptunes orbiting relatively bright M dwarfs. The second case employs photon counting, utilizing the electron-multiplying mode of the EMCCD to achieve 100−200 m/s velocimetry through cross-correlation of extremely low signal-to-noise ratio data. This innovative approach opens up observations of stars as faint as rsdss=19-20, an unexplored realm in RV studies. The main science niche for this mode is the confirmation of brown dwarfs orbiting cool stars and stellar dynamics within open clusters and young associations. Typically observed at low resolution, these targets face challenges in achieving RV precision better than a few km/s. VROOMM’s photon counting capability presents a novel solution for obtaining high-precision radial velocities in this challenging regime. We detail the unique features and capabilities of each operation mode, emphasizing the novel contributions of VROOMM in advancing precision RV measurements for a diverse range of exoplanet systems.
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