KEYWORDS: Calibration, James Webb Space Telescope, Stars, Point spread functions, Data modeling, Sensors, Astronomical interferometry, Equipment, Fourier optics, Astronomical interferometers
The multi-national James Webb Space Telescope (JWST) enables several new technologies, one of which is the first space-based infrared interferometer, the Aperture Masking Interferometry (AMI) mode of the Near Infrared Imager and Slitless Spectrograph (NIRISS). AMI is a niche but powerful tool for high resolution imaging of a variety of moderate- to high-contrast astronomical sources. The non-redundant mask (NRM) in the entrance pupil enables detection of structure below the classical Rayleigh diffraction limit, well inside the inner working angle of JWST’s coronagraphs. This explores a parameter space largely inaccessible to existing ground- and other space-based observatories. Early science observations leveraged the capabilities of this unique mode to observe dusty Wolf-Rayet binaries, spatially resolved solar system objects, massive exoplanet systems, and protoplanetary disks. The high quality of this space-based data demonstrated the need for improved analysis methods. We describe approaches to extracting interferometric observables, as well as pre- and post-extraction data cleaning routines we made available to the user community. We also discuss insights and unique challenges that were revealed during the commissioning, early calibration, and first science cycles of this promising observing mode: mitigation strategies for instrumental effects, lessons learned for optimizing observation configuration, and plans for ongoing calibration efforts. Knowledge gained from commissioning and calibration data – which are always non-proprietary – provide valuable insight into the capabilities and limitations of this mode, highlight areas that need improvement, and lay the groundwork for furthering JWST’s scientific objectives.
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.
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.
The first generation of ELT instruments includes an optical-infrared high resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs ([U]BV, RIZ, YJH) providing a spectral resolution of ∼100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 μm with the goal of extending it to 0.35-2.4 μm with the addition of an U arm to the BV spectrograph and a separate K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre-feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Modularity and fibre-feeding allows ANDES to be placed partly on the ELT Nasmyth platform and partly in the Coudé room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of almost 300 scientists and engineers which include the majority of the scientific and technical expertise in the field that can be found in ESO member states.
The ArmazoNes High Dispersion Echelle Spectrograph, or ANDES, is a second-generation instrument designed for use at the Extremely Large Telescope (ELT). As a fiber-fed echelle spectrograph, it consists of three spectral arms covering a wavelength range from 0.4 up to 1.8 μm, with the potential to extend coverage from 0.35 to 2.4 μm. This versatile instrument delivers an impressive spectral resolution of approximately 100,000, enabling highly sensitive observations of astronomical objects and phenomena, including exoplanets, fundamental scientific inquiries, and various cutting-edge research applications in astronomy. This article will describe the opto-mechanical design of the three cameras inside the YJH spectrograph. The mechanical design is based on an improved strategy used in instruments like CPAPIR, WIRCAM, SPIROU and NIRPS. The optical design is highly efficient and straightforward, employing the same four lenses for each band (Y, J, and H). The expected performance for the H-band will also be presented.
The first generation of ELT instruments includes an optical-infrared high resolution spectrograph, indicated as ELT-HIRES and recently christened ANDES (ArmazoNes high Dispersion Echelle Spectrograph). ANDES consists of three fibre-fed spectrographs (UBV, RIZ, YJH) providing a spectral resolution of ∼100,000 with a minimum simultaneous wavelength coverage of 0.4-1.8 µm with the goal of extending it to 0.35-2.4 µm with the addition of a K band spectrograph. It operates both in seeing- and diffraction-limited conditions and the fibre-feeding allows several, interchangeable observing modes including a single conjugated adaptive optics module and a small diffraction-limited integral field unit in the NIR. Its modularity will ensure that ANDES can be placed entirely on the ELT Nasmyth platform, if enough mass and volume is available, or partly in the Coudé room. ANDES has a wide range of groundbreaking science cases spanning nearly all areas of research in astrophysics and even fundamental physics. Among the top science cases there are the detection of biosignatures from exoplanet atmospheres, finding the fingerprints of the first generation of stars, tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The ANDES project is carried forward by a large international consortium, composed of 35 Institutes from 13 countries, forming a team of more than 200 scientists and engineers which represent the majority of the scientific and technical expertise in the field among ESO member states.
In less than a year, the James Webb Space Telescope (JWST) will inherit the mantle of being the world’s pre- eminent infrared observatory. JWST will carry with it an Aperture Masking Interferometer (AMI) as one of the supported operational modes of the Near-InfraRed Imager and Slitless Spectrograph (NIRISS) instrument. Aboard such a powerful platform, the AMI mode will deliver the most advanced and scientifically capable interferometer ever launched into space, exceeding anything that has gone before it by orders of magnitude in sensitivity. Here we present key aspects of the design and commissioning of this facility: data simulations (ami_sim), the extraction of interferometeric observables using two different approaches (IMPLANEIA and AMICAL), an updated view of AMI’s expected performance, and our reference star vetting programs.
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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