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.
We present a machine learning method to assign stellar parameters (temperature, surface gravity, metallicity) to the photometric data of large photometric surveys such as SDSS and SKYMAPPER. The method makes use of our previous effort in homogenizing and recalibrating spectroscopic data from surveys like APOGEE, GALAH, or LAMOST into a single catalog, which is used to inform a neural network. We obtain spectroscopic-quality parameters for millions of stars that have only been observed photometrically. The typical uncertainties are of the order of 100K in temperature, 0.1 dex in surface gravity, and 0.1 dex in metallicity and the method performs well down to low metallicity, were obtaining reliable results is known to be difficult.
In this paper, we present an overview of the software architecture for the ArmazoNes high Dispersion Echelle Spectrograph (ANDES) spectrograph, which has been developed as part of the recent System Architecture Review (SAR) held in October 2023. Our focus in this paper is twofold: we will detail about the control software and science tools that are set to be implemented. In particular, we provide a detailed view on how the ELT Instrument Control Framework has been effectively deployed to manage the complexities of a distributed instrument like ANDES. This entails a comprehensive discussion of the key architectural decisions we have made to meet the requirements of the project. Furthermore, we offer insights into the suite of science software that will be an integral part of the ANDES instrument. This includes the Exposure Time Calculator, Observation Preparation tools, and the Data Reduction Library. Finally, we provide an overview of the Data Analysis Software and the End-to-End ANDES simulator. These tools are crucial for processing and analyzing the data collected by the ANDES spectrograph.
We present the results of the ground-based observing campaign to build the grid of Spectro-Photometric Standard Stars (SPSS) for the absolute flux calibration of data gathered by Gaia, the European Space Agency (ESA) astrometric mission. The spectro-photometric standard stars catalog is characterized by an internal ≅1% accuracy (and sub-percent precision) and it is tied to the CALSPEC Vega and Sirius systems within ≅1%. The final list of SPSS and their flux tables are presented, together with all the quality parameters and associated stellar properties derived from Gaia and the literature. Improvements with respect to the previous SPSS release (Pancino et al. 2021) are discussed, concerning especially the flux accuracy in the red part of the spectrum, above 800 nm. The grid will be used to calibrate Gaia photometry and spectra fluxes in the DR4 and DR5 releases.
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.
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.
We describe the preliminary results of a ground-based observing campaign aimed at building a grid of approximately 200 spectro-photometric standard stars (SPSS), with an internal ≅1% accuracy (and sub-percent precision), tied to CALSPEC Vega and Sirius systems within ≅1%, for the absolute flux calibration of data gathered by Gaia, the European Space Agency (ESA) astrometric mission. The criteria for the selection and a list of candidates are presented, together with a description of the survey's strategy and the adopted data analysis methods. All candidates were also monitored for constancy (within ±5 mmag, approximately). The present version of the grid contains about half of the final sample, it has already reached the target accuracy but the precision will substantially improve with future releases. It will be used to calibrate the Gaia (E)DR3 release of spectra and photometry.
HIRES is the high-resolution spectrograph of the European Extremely Large Telescope at optical and near-infrared wavelengths. It consists of three fibre-fed spectrographs providing a wavelength coverage of 0.4-1.8 µm (goal 0.35-2.4 µm) at a spectral resolution of 100,000. The fibre-feeding allows HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU in the NIR. Therefore, it will be able to operate both in seeing- and diffraction-limited modes. Its modularity will ensure that HIRES can be placed entirely on the Nasmyth platform, if enough mass and volume is available, or part on the Nasmyth and part in the Coud`e room. ELT-HIRES has a wide range of 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 (PopIII), tests on the stability of Nature’s fundamental couplings, and the direct detection of the cosmic acceleration. The HIRES consortium is composed of more than 30 institutes from 14 countries, forming a team of more than 200 scientists and engineers.
The HIRES-ELT instrument foresees an observing mode that delivers integral field high resolution spectroscopy with spatial sampling down to the diffraction limit of the ELT telescope. The IFU-SCAO module presented here is sub-system of the front-end of HIRES-ELT that includes two modules: SCAO and IFU. The first is the wavefront sensor, based on a pyramid beam-splitter, that provides the guiding on the reference star and the analysis of the incoming wavefront; the second is the module that transforms the incoming f/17.7 light beam from the telescope to the appropriate f/numbers to feed the spectrometer fibers-array with the required spatial scale. In this paper, we will present the SCAO optical design to allow the exoplanet atmosphere detection in reflection. To achieve this goal, we studied a feasible pyramid wavefront sensor to be inserted in a sliding arm of the HIRES front end. The CCD camera is based on a CCD220 chip in which will be imaged the telescope pupil, sampled with a 90x90 sub-aperture grid. A total of 4089 Karhunen-Loeve modes have been generated and used to close an end-to-end simulation. The AO loop runs up to 1000 KHz and it allows to shrink the PSF to the diffraction limits of the telescope ant to achieve Strehl Ratio (SR) above 70% in best seeing case up to magnitude 15 in H-band and a SR permanently above 40%, same band, up to magnitude 14 in case of median seeing. For λ=1600nm the 50% of energy is reached before 1 λ/D for all the plotted I-magnitude under the best seeing conditions. Under Median seeing conditions, the 50% is reached before 2λ/D up to I-mag 13. For λ=1000nm instead, we reach the 50% of encircled energy before a radius of 2λ/D for I-mag less than 14 and after 5λ/D for I-mag greater than 15 in the best seeing case. For each IFU spatial sampling and resolution, we can reach a contrast of 103 at a distance of 4 spaxels from central peak.
We present an application of the HIRES End-to-End (E2E) simulator and HIRES Exposure Time Calculator (ETC) to derive a more detailed behavior of the spectrograph efficiency by including physical modeling of diffraction at the echelle grating and the cross-disperser. The result will be used with the Spectral Energy Distributions of calibration lights for wavelength solutions and flat fielding to quantitatively characterize the spectrograph in terms of achieved accuracy. By showing the contribution of photon noise, detector noise and cross talk between adjacent fibers we discuss methods that could be used to determine the overall performance of the instrument, in term of the capability of photon collection as well as especially on the achieved precision on wavelength calibration that translates directly in radial velocity accuracy of the scientific light.
The first generation of ELT instruments will include an optical-infrared High Resolution Spectrograph, conventionally indicated as ELT-HIRES. This paper describes the optical design and overall architecture of the Integral Field Unit (IFU) that will fed the spectrograph. The module have the possibility to change the spaxel dimension thanks to a series of reflection mirrors and using a fast tip tilt mirror the position of the re-imaged foci on the fiber bundles can be adjusted looking at the focus image that is visible using a fiber viewer IR camera.
GIANO-B is the high resolution near-infrared (NIR) spectrograph of the Telescopio Nazionale Galileo (TNG), which started its regular operations in October 2017. Here we present GIANO-B Online Data Reduction Software (DRS) operating at the Telescope.
GIANO-B Online DRS is a complete end-to-end solution for the spectrograph real-time data handling. The Online DRS provides management, processing and archival of GIANO-B scientific and calibration data. Once the instrument control software acquires the exposure ramp segments from the detector, the DRS ensures the complete data flow until the final data products are ingested into the science archive. A part of the Online DRS is GOFIO software, which performs the reduction process from ramp-processed 2D spectra to extracted and calibrated 1D spectra.
A User Interface (UI) developed as a part of the Online DRS provides basic information on the final reduced data, thus allowing the observer to take decisions in real-time during the night and adjust the observational strategy as needed.
GIANO is the IR high resolution spectrograph of the TNG. It covers the 950-2450 nm wavelengths range in a single shot at a resolving power of R=50,000. This document describes the first fundamental steps of the data reduction, namely eliminating the curvature of the traces and the tilt of the slit images. These effects can be accurately modeled and corrected using a physical model of the instrument. We find that the curvature and tilt parameters did not vary during the whole lifetime of the instrument. In particular, they were not affected by thermal cycles or by the works performed to mount the spectrometer on its new interface. A similar ab-initio modeling is also applied to the wavelength calibration that can be accurately (0.03 pixel r.m.s.) defined using a minimum number of parameters to fit. This approach is particularly useful when using a calibration source with an irregular wavelengths coverage; e.g. for the U-Ne lamp that has only few lines in the 2000 nm - 2300 nm wavelengths range.
KEYWORDS: Calibration, Lamps, Sensors, Spectrographs, Signal to noise ratio, Infrared radiation, Spectroscopy, Signal detection, Data processing, Near infrared spectroscopy
The NIR echelle spectrograph GIANO-B at the Telescopio Nazionale Galileo is equipped with a fully automated online DRS: part of this pipeline is the GOFIO reduction software, that processes all the observed data, from the calibrations to the nodding or stare images. GOFIO reduction process includes bad pixel and cosmic removal, flat-field and blaze correction, optimal extraction, wavelength calibration, nodding or stare group processing. An offline version of GOFIO will allow the users to adapt the reduction to their needs, and to compute the radial velocity using telluric lines as a reference system. GIANO-B may be used simultaneously with HARPS-N in the GIARPS observing mode to obtain high-resolution spectra in a wide wavelength range (383-2450 nm) with a single acquisition. In this framework, GOFIO, as part of the online DRS, provides fast and reliable data reduction during the night, in order to compare the infrared and visible observations on the fly.
GIARPS (GIAno and haRPS) is a project devoted to have on the same focal station of the Telescopio Nazionale Galileo (TNG) both high resolution spectrographs, HARPS–N (VIS) and GIANO–B (NIR), working simultaneously. This could be considered the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at a resolution of 50,000 in the NIR range and 115,000 in the VIS and over in a wide spectral range (0.383−2.45 μm) in a single exposure. The science case is very broad, given the versatility of such an instrument and its large wavelength range. A number of outstanding science cases encompassing mainly extra-solar planet science starting from rocky planets search and hot Jupiters to atmosphere characterization can be considered. Furthermore both instruments can measure high precision radial velocities by means the simultaneous thorium technique (HARPS–N) and absorbing cell technique (GIANO–B) in a single exposure. Other science cases are also possible. GIARPS, as a brand new observing mode of the TNG started after the moving of GIANO–A (fiber fed spectrograph) from Nasmyth–A to Nasmyth–B where it was re–born as GIANO–B (no more fiber feed spectrograph). The official Commissioning finished on March 2017 and then it was offered to the community. Despite the work is not finished yet. In this paper we describe the preliminary scientific results obtained with GIANO–B and GIARPS observing mode with data taken during commissioning and first open time observations.
We present the results from the phase A study of ELT-HIRES, an optical-infrared High Resolution Spectrograph for ELT, which has just been completed by a consortium of 30 institutes from 12 countries forming a team of about 200 scientists and engineers. The top science cases of ELT-HIRES will be the detection of life signatures from exoplanet atmospheres, tests on the stability of Nature’s fundamental couplings, the direct detection of the cosmic acceleration. However, the science requirements of these science cases enable many other groundbreaking science cases. The baseline design, which allows to fulfil the top science cases, consists in a modular fiber- fed cross-dispersed echelle spectrograph with two ultra-stable spectral arms providing a simultaneous spectral range of 0.4-1.8 μm at a spectral resolution of ~100,000. The fiber-feeding allows ELT-HIRES to have several, interchangeable observing modes including a SCAO module and a small diffraction-limited IFU.
High resolution spectroscopy has been considered of a primary importance to exploit the main scientific cases foreseen for ESO ELT, the Extremely Large Telescope, the future largest optical-infrared telescope in the world. In this context ESO commissioned a Phase-A feasibility study for the construction of a high resolution spectrograph for the ELT, tentatively named HIRES. The study, which lasted 1.5 years, started on March 2016 and was completed with a review phase held at Garching ESO headquarters with the aim to assess the scientific and technical feasibility of the proposed instrument. One of the main tasks of the study is the architectural design of the software covering all the aspects relevant to control an astronomical instrument: from observation preparation through instrument hardware and detectors control till data reduction and analysis. In this paper we present the outcome of the Phase-A study for the proposed HIRES software design highlighting its peculiarities, critical areas and performance aspects for the whole data flow. The End-toEnd simulator, a tool already capable of simulating HIRES end products and currently being used to drive some design decision, is also shortly described.
GIARPS (GIAno and haRPS) is a project devoted to have on the same focal station of the Telescopio Nazionale Galileo (TNG) both the high resolution spectrographs HARPS-N (VIS) and GIANO (NIR) working simultaneously. This could be considered the first and unique worldwide instrument providing cross-dispersed echelle spectroscopy at a high resolution (R=115,000 in the visual and R=50,000 in the IR) and over in a wide spectral range (0.383 - 2.45 μm) in a single exposure. The science case is very broad, given the versatility of such an instrument and the large wavelength range. A number of outstanding science cases encompassing mainly extra-solar planet science starting from rocky planet search and hot Jupiters, atmosphere characterization can be considered. Furthermore both instrument can measure high precision radial velocity by means the simultaneous thorium technique (HARPS - N) and absorbing cell technique (GIANO) in a single exposure. Other science cases are also possible. Young stars and proto- planetary disks, cool stars and stellar populations, moving minor bodies in the solar system, bursting young stellar objects, cataclysmic variables and X-ray binary transients in our Galaxy, supernovae up to gamma-ray bursts in the very distant and young Universe, can take advantage of the unicity of this facility both in terms of contemporaneous wide wavelength range and high resolution spectroscopy.
HIRES, a high resolution spectrometer, is one of the first five instruments foreseen in the ESO roadmap for the E-ELT. This spectrograph should ideally provide full spectral coverage from the UV limit to 2.5 microns, with
a resolving power from R∼10,000 to R∼100,000. At visual/blue wavelengths, where the adaptive optics (AO)
cannot provide an efficient light-concentration, HIRES will necessarily be a bulky, seeing-limited instrument.
The fundamental question, which we address in this paper, is whether the same approach should be adopted in the near-infrared range, or HIRES should only be equipped with compact infrared module(s) with a much smaller aperture, taking advantage of an AO-correction. The main drawbacks of a seeing-limited instrument at all wavelengths are: i) Lower sensitivities at wavelengths dominated by thermal background (red part of the K-band). ii) Much higher volumes and costs for the IR spectrograph module(s). The main drawbacks of using smaller, AO-fed IR module(s) are: i) Performances rapidly degrading towards shorter wavelengths (especially J e Y bands). ii) Different spatial sampling of extended objects (the optical module see a much larger area on the sky). In this paper we perform a trade-off analysis and quantify the various effects that contribute to improve or deteriorate the signal to noise ratio. In particular, we evaluate the position of the cross-over wavelength at which AO-fed instruments starts to outperform seeing-limited instruments. This parameter is of paramount importance for the design of the part of HIRES covering the K-band.
Giano is a Cryogenic Spectrograph located in T.N.G. (Spain) and commissioned in 2013. It works in the range 950-2500
nm with a resolving power of 50000.
This instrument was designed and built for direct feeding from the telescope [2]. However, due to constraints imposed on
the telescope interfacing during the pre-commissioning phase, it had to be positioned on the rotating building, far from
the telescope focus. Therefore, a new interface to the telescope, based on IR-transmitting ZBLAN fibers with 85μm core,
was developed. Originally designed to work directly at the f/11 nasmyth focus of the telescope, in 2011 it has decided to
use a fiber to feed it.
The beam from the telescope is focused on a double fiber boundle by a Preslit Optical Bench attached to the Nasmith A
interface of the telescope. This Optical Bench contains the fiber feeding system and other important features as a guiding
system, a fiber viewer, a fiber feed calibration lamp and a nodding facility between the two fibers. The use of two fibers
allow us to have in the echellogram two spectrograms side by side in the same acquisition: one of the star and the other
of the sky or simultaneously to have the star and a calibration lamp. Before entering the cryostat the light from the fiber
is collected by a second Preslit Optical Bench attached directly to the Giano cryostat: on this bench the correct f-number
to illuminate the cold stop is generated and on the same bench is placed an image slicer to increase the efficiency of the
system.
Present telescopes and future extremely large telescopes make use of fiber-fed spectrographs to observe at optical and
infrared wavelengths. The use of fibers largely simplifies the interfacing of the spectrograph to the telescope. At a high
spectral resolution (R>50,000) the fibers can be used to achieve very high spectral accuracy.
GIANO is an infrared (0.95-2.5μm) high resolution (R=50,000) spectrometer[1] [2] [3] that was recently commissioned
at the TNG telescope (La Palma). This instrument was designed and built for direct feeding from the telescope [4].
However, due to constraints imposed on the telescope interfacing during the pre-commissioning phase, it had to be
positioned on the rotating building, far from the telescope focus. Therefore, a new interface to the telescope, based on
IR-transmitting ZBLAN fibers with 85μm core, was developed.
In this article we report the first, preliminary results of the effects of these fibers on the quality of the recorded spectra
with GIANO and with a similar spectrograph that we set-up in the laboratory. The effects can be primarily associated to
modal-noise (MN) that, in GIANO, is much more evident than in optical spectrometers, because of the much longer
wavelengths.
GIANO is the high resolution near IR spectrograph recently commissioned at the 3.58m Telescopio Nazionale Galileo in
La Palma (Spain). GIANO is the first worldwide instrument providing cross-dispersed echelle spectroscopy at a
resolution of 50,000 over the 0.95 – 2.45 micron spectral range in a single exposure. There are outstanding science cases
in the research fields of exo-planets, Galactic stars and stellar populations that could strongly benefit from GIANO
observations down to a magnitude limit comparable to that of 2MASS. The instrument includes a fully cryogenic
spectrograph and an innovative fiber system transmitting out to the K band. It also represents a formidable laboratory to
test performances and prototype solutions for the next generation of high resolution near IR spectrographs at the ELTs.
First results from sky tests at the telescope and science verification occurred between July 2012 and October 2013 will
be presented.
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