In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high instrumental efficiency ( > 37%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R > 20, 000 (with a lower-resolution, sky-limited mode of R ∼ 7, 000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio – SNR– ∼ 20 per spectral resolution element at 313 nm for U ∼ 17.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics: i) access to key lines of stellar spectra (e.g. lighter elements, in particular Beryllium), extragalactic studies (e.g. circumgalactic medium of distant galaxies, cosmic UV background) and follow-up of explosive transients. We present the CUBES instrument design, currently in Phase-C and approaching the final design review, summarizing the hardware architecture and interfaces between the different subsystems as well as the relevant technical requirements. We describe the optical, mechanical, electrical design of the different subsystems (from the telescope adapter and support structure, through the main opto-mechanical path, including calibration unit, detector devices and cryostat control, main control electronics), detailing peculiar instrument functions like the Active Flexure Compensation (AFC). Furthermore, we outline the AIT/V concept and the main instrument operations giving an overview of its software ecosystem. Installation at the VLT is planned for 2028/2029 and first science operations in late 2029.
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 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.
KEYWORDS: Spectrographs, Stars, Chemical elements, Ultraviolet radiation, Telescopes, Galactic astronomy, Sensors, Astronomy, Signal to noise ratio, Near ultraviolet
In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at ground-UV wavelengths for the foreseeable future. The Cassegrain U-Band Efficient Spectrograph (CUBES) has been designed to provide high-efficiency (> 40%) observations in the near UV (305-400 nm requirement, 300-420 nm goal) at a spectral resolving power of R >20, 000 (with a lower-resolution, sky-limited mode of R ~7, 000). With the design focusing on maximizing the instrument throughput (ensuring a Signal to Noise Ratio (SNR) ~20 per high-resolution element at 313 nm for U ~18.5 mag objects in 1h of observations), it will offer new possibilities in many fields of astrophysics, providing access to key lines of stellar spectra: a tremendous diversity of iron-peak and heavy elements, lighter elements (in particular Beryllium) and light-element molecules (CO, CN, OH), as well as Balmer lines and the Balmer jump (particularly important for young stellar objects). The UV range is also critical in extragalactic studies: the circumgalactic medium of distant galaxies, the contribution of different types of sources to the cosmic UV background, the measurement of H2 and primordial Deuterium in a regime of relatively transparent intergalactic medium, and follow-up of explosive transients. The CUBES project completed a Phase A conceptual design in June 2021 and has now entered the detailed design and construction phase. First science operations are planned for 2028.
Astrocook is a software environment to analyze quasar spectra in a variety of ways. It aims to break the static pipeline paradigm by enforcing a new flexible approach to data treatment, in which complex automatic workflows are dynamically created from a wide set of atomic operations (hence the tagline: “a thousand recipes to cook a spectrum”). We will focus both on the novel algorithms that have been implemented and on the scientific validation and reproducibility of the results. To highlight the benefits of the Astrocook approach for both interactive and automatic analysis, two specific use cases are discussed (one of which was used in practice to process observational data from the QUBRICS survey).
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.
Alongside future observations with the new European Extremely Large Telescope (ELT), optimised instruments on the 8-10m generation of telescopes will still be competitive at ‘ground UV’ wavelengths (3000-4000 Å). The near UV provides a wealth of unique information on the nucleosynthesis of iron-peak elements, molecules, and neutron-capture elements. In the context of development of the near-UV CUBES spectrograph for ESO’s Very Large Telescope (VLT), we are investigating the impact of spectral resolution on the ability to estimate chemical abundances for beryllium and more than 30 iron-peak and heavy elements. From work ahead of the Phase A conceptual design of CUBES, here we present a comparison of the elements observable at the notional resolving power of CUBES (R ~ 20,000) to those with VLT-UVES (R ~ 40,000). For most of the considered lines signal- to-noise is a more critical factor than resolution. We summarise the elements accessible with CUBES, several of which (e.g. Be, Ge, Hf) are now the focus of quantitative simulations as part of the ongoing Phase A study.
Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) is the latest instrument installed at the European Southern Observatory (ESO)-Very Large Telescope (VLT) site in Chile. To fulfill its scientific requirements, ESPRESSO can operate both in 1-UT mode (using any of the four VLT unit telescopes) and in 4-UT mode. In 4-UT mode, the light of the four 8-m telescopes is combined in an incoherent focus to form a 16-m equivalent telescope, thus providing the largest collecting area ever at optical-NIR wavelengths. In ESPRESSO, dedicated front end units (FEUs) allow collection of the light coming from the telescope tunnels conveying it through fibers to the spectrograph. All the functionalities of the FEUs are managed by the instrument control electronics (ICE) and software. We aim to provide the detailed description of the realization of this ICE, based on Beckhoff programmable logic controllers. In particular, we show ESPRESSO ICE functions distribution, the motion control characteristics, and the main validation tests performed during the European and Chilean integration phase, which led to technical acceptance of ESPRESSO by ESO before its first light achieved at the end of 2017.
ESPRESSO, the next generation ESO VLT high-resolution ultra-stable spectrograph, after the successful Preliminary Acceptance Europe held at the integration site of the Observatory of Geneva, has been re-integrated at Paranal and started its commissioning activities at the end of 2017. One critical aspect for ESPRESSO future operations, compared with other instruments currently running at ESO, is the way it will be operated which poses several constraints on its data flow. ESPRESSO has been conceived and developed as a “truly science-grade products generating machine” thanks to its fixed format and long-term stability. In addition to the Data Reduction Software (DRS), a Data Analysis Software (DAS), developed within the standard ESO Data Flow System, will be provided to the users – a novelty for the instruments at Paranal. Moreover, ESPRESSO will be fed either by the light of any of the UTs or by the incoherently combined light of up to four UTs, a feature which required a re-thinking of the current Paranal data handling injection schema. In this paper, after describing the main challenges and peculiarities of the ESPRESSO data flow system listed above, we will present the results of the first commissioning activities and the lessons learned to handle data produced by an instrument with such ambitious scientific requirements.
When long term instrument stability is required, traditional alignment techniques based on bulky and/or flexible mountings can not be used due to their reduced stiffness. Mechanical alignment of optical systems is nowadays possible thanks to different 3D Coordinate Measuring Machines, as the Laser Tracker, the Articulated and Cartesian Arms. In this paper we describe the methods we considered for the integration and alignment of ESPRESSO, the very high resolution visible spectrograph for the ESO VLT, now under commissioning phase at Paranal Observatory. Different examples of the Front End (FE), the Anamorphic Pupil Slicer Unit (APSU), and the spectrograph itself will be provided, to demonstrate that it is possible to align an optical system with mechanical methods with minimal optical feedbacks, reaching in an almost ‘blind’ way the best optical performances.
In the era of Extremely Large Telescopes, the current generation of 8-10m facilities are likely to remain competitive at far-blue visible wavelengths for the foreseeable future. High-efficiency (<20%) observations of the ground UV (300- 400 nm) at medium resolving power (R~20,000) are required to address a number of exciting topics in stellar astrophysics, while also providing new insights in extragalactic science. Anticipating strong demand to better exploit this diagnostic-rich wavelength region, we revisit the science case and instrument requirements previously assembled for the CUBES concept for the Very Large Telescope.
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.
The ESPRESSO (Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations) spectrograph, after the preliminary tests carried out at the Astronomical Observatory of Geneva (Switzerland), has been shipped and re-integrated at the Very Large Telescope (VLT) site in Cerro Paranal (Chile). The instrument control software, designed and developed at INAF–Osservatorio Astronomico di Trieste, had to face several challenges since ESPRESSO is the first instrument placed at the VLT Coud`e Combined Laboratory able to be fed by up to 4 Telescope Units simultaneously (through an incoherent focus), and whose electronics is based on Beckhoff PLCs. Moreover, ESPRESSO requires a careful stabilization of the field image in order to maximize the light flux through the fiber hole, and reach the instrumental radial-velocity precision level of 10 cm/s. These circumstances lead to the development of a few solutions specifically dedicated to ESPRESSO. In this paper we will summarize the features of the ESPRESSO control software, the tests performed during the integration phase in Europe, and discuss the main performances obtained during the commissioning phase and ”first light” observations in Chile
Astrocook is a new Python package to analyze the spectra of quasi-stellar objects (QSOs) from the near-UV band to the near-infrared band. The project stems from the lessons learned in developing the data analysis software for the VLT ESPRESSO spectrograph. The idea is to leverage numerical libraries like SciPy, NumPy, and Lmfit and astronomical libraries like Astropy to produce a collection of high-level recipes capable of interpreting the features observed in QSO spectra (such as the emission continuum and the absorption systems) in an automated and validated way. The package provides great flexibility in designing the operational workflow, as well as a set of interactive tools to apply the recipes in a seamless way. The aim is to achieve the combination of accuracy, stability, and repeatability of the procedure that is required by several compelling science cases in the era of ”precision cosmology” (e.g. the measurement of a possible variability in the value of fundamental constants, and the direct measurement of the accelerated expansion of the Universe).
In this paper we will review the ESPRESSO guiding algorithm for the Front End subsystem. ESPRESSO, the Echelle Spectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will be installed on ESO’s Very Large Telescope (VLT). The Front End Unit (FEU) is the ESPRESSO subsystem which collects the light coming from the Coudè Trains of all the Four Telescope Units (UTs), provides Field and Pupil stabilization better than 0.05’’ via piezoelectric tip tilt devices and inject the beams into the Spectrograph fibers. The field and pupil stabilization is obtained through a re-imaging system that collects the halo of the light out of the Injection Fiber and the image of the telescope pupil. In particular, we will focus on the software design of the system starting from class diagram to actual implementation. A review of the theoretical mathematical background required to understand the final design is also reported. We will show the performance of the algorithm on the actual Front End by adoption of telescope simulator exploring various scientific requirements.
The first generation of E-ELT instruments will include an optic-infrared High Resolution Spectrograph, conventionally indicated as EELT-HIRES, which will be capable of providing unique breakthroughs in the fields of exoplanets, star and planet formation, physics and evolution of stars and galaxies, cosmology and fundamental physics. A 2-year long phase A study for EELT-HIRES has just started and will be performed by a consortium composed of institutes and organisations from Brazil, Chile, Denmark, France, Germany, Italy, Poland, Portugal, Spain, Sweden, Switzerland and United Kingdom. In this paper we describe the science goals and the preliminary technical concept for EELT-HIRES which will be developed during the phase A, as well as its planned development and consortium organisation during the study.
ESPRESSO, Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, is now under the assembly, integration and verification phase and will be installed beginning next year at Paranal Observatory on ESO's Very Large Telescopes. The Front End is the modular system in the Combined Coudé Laboratory receiving the light from the four VLT Units, providing the needed connection between the input signal, i.e., object light, sky light, and calibration light, to feed the spectrograph through optical fibers. The modular concept of the FE Units drove the system design and the alignment workflow. We will show the integration method of the single FE modules adopted to guarantee the necessary repeatability between the different Units. The performances of the system in terms of image quality and encircled energy in the observed point spread function are reported. Finally, the strategy followed in the Paranal Combined Coudè Laboratory to define the convergence point of the four UTs is described, along with the procedure used to align the ground plates, the main structure, and the mode selector.
The Echelle Spectrograph for Rocky Exoplanets and Stable Spectral Observations (ESPRESSO) requires active-loop stabilization of the light path from the telescope to the spectrograph, in order to achieve its centimeter-per- second precision goal. This task is accomplished by moving the mirrors placed along the light path by means of piezoelectric actuators. Two cameras are used to acquire the field and pupil images, and the required corrections are dynamically calculated and applied to the piezos. In this paper we will discuss the camera usage, performance and network bandwidth requirements for the ESPRESSO scientific operations.
The current E-ELT instrumentation plan foresees a High Resolution Spectrograph conventionally indicated as EELTHIRES whose Phase A study has started in March 2016. Since 2013 however, a preliminary study of a modular E-ELT instrument able to provide high-resolution spectroscopy (R~100,000) in a wide wavelength range (0.37-2.5 μm) has been already conducted by an international consortium (termed “HIRES initiative”). Taking into account the requirements inferred from this preliminary work in terms of both high-level operations as well as low-level control, we will present in this paper possible solutions for HIRES hardware and software architecture. The validity of the proposed architectural and hardware choices will be eventually discussed based also on the experience gained on a real-working instrument, ESPRESSO, the next generation high-stability spectrograph for the VLT and to certain extent the precursor of HIRES.
ESPRESSO, the Echelle SPectrograph for Rocky Exoplanet and Stable Spectroscopic Observations of the ESO - Very Large Telescope site, is now in its integration phase. The large number of functions of this complex instrument are fully controlled by a Beckhoff PLC based control electronics architecture. Four small and one large cabinets host the main electronic parts to control all the sensors, motorized stages and other analogue and digital functions of ESPRESSO. The Instrument Control Electronics (ICE) is built following the latest ESO standards and requirements. Two main PLC CPUs are used and are programmed through the TwinCAT Beckhoff dedicated software. The assembly, integration and verification phase of ESPRESSO, due to its distributed nature and different geographical locations of the consortium partners, is quite challenging. After the preliminary assembling and test of the electronic components at the Astronomical Observatory of Trieste and the test of some electronics and software parts at ESO (Garching), the complete system for the control of the four Front End Unit (FEU) arms of ESPRESSO has been fully assembled and tested in Merate (Italy) at the beginning of 2016. After these first tests, the system will be located at the Geneva Observatory (Switzerland) until the Preliminary Acceptance Europe (PAE) and finally shipped to Chile for the commissioning. This paper describes the integration strategy of the ICE workpackage of ESPRESSO, the hardware and software tests that have been performed, with an overall view of the experience gained during these project’s phases.
The Echelle SPectrograph for Rocky Exoplanets and Stable Spectral Observations (ESPRESSO) is an ultrastable spectrograph for the coudé-combined focus of the VLT. With its unprecedented capabilities (resolution up to fi 200,000, wavelength range from 380 to 780 nm; centimeter-per-second precision in wavelength calibration), ESPRESSO is a prime example of the now spreading science machine concept: a fully-integrated system carefully designed to perform direct scientific measurements on the data, in a matter of minutes from the execution of the observations. This approach is motivated by the very specific science cases of the instrument (search for terrestrial exoplanets with the radial velocity method; measure of the variation of fundamental constants using the spectral signatures of the inter-galactic medium) and is achieved by a dedicated tool for spectral analysis, the data analysis software or DAS, targeted to both stellar and quasar spectra. In this paper, we describe characteristics and performances of the DAS, with particular emphasis on the novel algorithms for stellar and quasar analysis (continuum fitting and interpretation of the absorption features).
The current E-ELT instrumentation plan foresees a High Resolution Spectrograph conventionally indicated as HIRES whose Phase A study has started in 2016. An international consortium (stemmed from the existing "HIRES initiative") is conducting a preliminary study of a modular E-ELT instrument able to provide highresolution spectroscopy (R ~ 100; 000) in a wide wavelength range (0.37-2.5 μm). For the aims of data treatment (which encompasses both the reduction and the analysis procedures) an end-to-end approach has been adopted, to directly extract scientific information from the observations with a coherent set of interactive, properly validated software modules. This approach is favoured by the specific science objectives of the instrument, which pose unprecedented requirements in terms of measurement precision and accuracy. In this paper we present the architecture envisioned for the HIRES science software, building on the lessons learned in the development of the data analysis software for the ESPRESSO ultra-stable spectrograph for the VLT.
The Echelle SPectrograph for Rocky Exoplanets and Stable Spectral Observations (ESPRESSO) is an extremely stable high-resolution spectrograph currently under construction, to be placed at Paranal Observatory in the ESO VLT Combined Coudé Laboratory (CCL). With its groundbreaking characteristics (resolution up to ∼200,000; wavelength range from 380 to 780 nm; centimeter-per-second precision in wavelength calibration) and its very specific science cases (search for terrestrial exoplanets with the radial velocity method; measure of the variation of fundamental constants through observations of QSO spectra), ESPRESSO is aimed to be a real "science machine", an instrument whose data flow subsystems are designed in a fully-integrated way to directly extract scientific results from observations. To this purpose, an end-to-end operations scheme will be properly tackled through tailored observation strategy, observation preparation, data reduction and data analysis tools. The software design has successfully passed the ESO final design review in May 2013 and it is now in development phase. In this paper we present the final design for the ESPRESSO data flow system (DFS) with some insights into the new concepts and algorithms that will be introduced for observation strategy/preparation and data reduction/analysis. Eventually, peculiarities and challenges needed to adapt the ESPRESSO DFS in the pre-existing ESO/VLT DFS framework are outlined.
The current instrumentation plan for the E-ELT foresees a High Resolution Spectrograph conventionally indicated as
HIRES. Shaped on the study of extra-solar planet atmospheres, Pop-III stars and fundamental physical constants, HIRES
is intended to embed observing modes at high-resolution (up to R=150000) and large spectral range (from the blue limit to the K band) useful for a large suite of science cases that can exclusively be tackled by the E-ELT. We present in this
paper the solution for HIRES envisaged by the "HIRES initiative", the international collaboration established in 2013 to
pursue a HIRES on E-ELT.
This paper presents the Espresso Exposure Meter (EM) implementation. ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will be installed on ESOs Very Large Telescope (VLT). The light coming from the Telescope through a Coude Focus of all the Four Telescope Units (UTs) will be collected by the Front End Unit that provides Field and Pupil stabilisation and injects the beams into the Spectrograph fibers. An advanced Exposure Meter system will be used to correct Radial Velocity (RV) obtained from the scientific spectrum for the Earth relative motion. In this work we will present the performance of an innovative concept for the Exposure Meter system based on a Charge Coupled Device (CCD) with a chromatic approach for the calculation of the Mean Time of Exposure (MTE). The MTE is a fundamental quantity used for the correction of RV for the Earth relative motion during exposure. In particular, splitting the light in different chromatic channels on the CCD, we will probe for potential chromatic effects on the calculation of the MTE in each channel and how they could be used in order to perform the correction of RV. The paper is accompanied by a fully described numerical analysis that keeps into view a key performance evaluation for different stellar spectral types (B to M spectral main sequence classes).
The opto-mechanical conceptual design for the Front-End unit and the calibration unit of the ESPRESSO Spectrograph is
described in this paper. The front end system exploits a modular concept. Each FEU receive the beam directly from the
relative Telescope Coudé Train and the calibration light from the calibration unit. On the other side the FEU feeds the
fibers that carry the light to the spectrograph, corresponding in number and size to the scientific observing modes
conceived for Espresso. The selection is made through a Toggling Unit. Purpose of the Front/End is to provide the
needed connection between the input signal, i.e. Object light, Sky light, Calibration light, and the given output fiber in
any of the foreseen observing modes.
This paper presents the Espresso Anamorphic pupil Slicer (APSU) implementation. For ESPRESSO that will be installed
on ESO’s Very Large Telescope (VLT). In this work we will present the design and trade off for the pupil slicing system
introduced in order to increase the resolving power, effectively decreasing slit width. It’s based onto simplified optical
component that introduce large anamorphism while keeping low aberrations by means of cylindrical optics. We describe
here the trade off between slicing through two adjacent squared doublets and two achromatic prisms. Preliminary
integration and procurement is also discussed here.
ESPRESSO is an ultra-stable fiber-fed spectrograph designed to combine incoherently the light coming from up to 4 Unit Telescopes of the ESO VLT. From the Nasmyth focus of each telescope the light, through an optical path, is fed by the Coudé Train subsystems to the Front End Unit placed in the Combined Coudé Laboratory. The Front End is composed by one arm for each telescope and its task is to convey the incoming light, after a calibration process, into the spectrograph fibers. To perform these operations a large number of functions are foreseen, like motorized stages, lamps, digital and analog sensors that, coupled with dedicated Technical CCDs (two per arms), allow to stabilize the incoming beam up to the level needed to exploit the ESPRESSO scientific requirements. The Instrument Control Electronics goal is to properly control all the functions in the Combined Coudé Laboratory and the spectrograph itself. It is fully based on a distributed PLC architecture, abandoning in this way the VME-based technology previously adopted for the ESO VLT instruments. In this paper we will describe the ESPRESSO Instrument Control Electronics architecture, focusing on the distributed layout and its interfaces with the other ESPRESSO subsystems.
KEYWORDS: Prisms, Clocks, Tolerancing, Silica, Optics manufacturing, Assembly tolerances, Prototyping, Manufacturing, Control systems, Chemical elements
The multiprism device is a crucial component of the Espresso Anamorphic pupil Slicer (APSU). At the end of the slicer,
is necessary to differently fold each field to correctly illuminate the echelle. The solution is made by gluing cylindrical
prisms with proper bending low angle onto a support double plate silica window. We present here the integrated robotic
system conceived to reach the required tolerances in term of alignment and Integration. It consist in a tip tilt stage to
select the folding angle, coupled to an x-y stage to position the elements and a z axis to perform the gluing.
Keywords: Extra-solar Planet Atmospheres, High Resolution Spectroscopy, Espresso, front End
ESPRESSO is the next generation ground based European exoplanets hunter. It will combine the efficiency of modern
echelle spectrograph with extreme radial-velocity and spectroscopic precision. It will be installed at Paranal's VLT in
order to achieve two magnitudes gain with respect to its predecessor HARPS, and the instrumental radial-velocity
precision will be improved to reach 10 cm/s level. We have constituted a Consortium of astronomical research institutes
to fund, design and build ESPRESSO on behalf of and in collaboration with ESO, the European Southern Observatory.
The spectrograph will be installed at the Combined Coudé Laboratory (CCL) of the VLT, it will be linked to the four 8.2
meters Unit Telescopes through four optical "Coudé trains" and will be operated either with a single telescope or with up
to four UTs, enabling an additional 1.5 magnitude gain. Thanks to its characteristics and ability of combining
incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in many fields of astronomy. Our
main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of
quiet, near-by G to M-dwarfs, and the analysis of the variability of fundamental physical constants. The project is, for
most of its workpackages, in the procurement or development phases, and the CCL infrastructure is presently under
adaptation work. In this paper, we present the scientific objectives, the capabilities of ESPRESSO, the technical solutions
for the system and its subsystems. The project aspects of this facility are also described, from the consortium and
partnership structure to the planning phases and milestones.
This paper presents the Espresso Anamorphic pupil Slicer (APSU) implementation. ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will be installed on ESOs Very Large Telescope (VLT). In this work we will present the design and trade-off for the pupil slicing system introduced in order to increase the resolving power, effectively decreasing slit width. Its based onto simplified optical component that introduce large anamorphism while keeping low aberrations by means of cylindrical optics. We describe here the trade-off between slicing through two adjacent squared doublets and two achromatic prisms.
ESPRESSO is the next European exoplanets hunter. It will combine the efficiency of modern echelle spectrograph with extreme radial-velocity precision. It will be installed at Paranal's VLT in order to achieve two magnitudes gain with respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level. We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of and in collaboration with ESO, the European Southern Observatory. The project has passed the final design review in May 2013. The spectrograph will be installed at the Combined Coudé Laboratory of the VLT, it will be linked to the four 8.2 meters Unit Telescopes through four optical "Coudé trains" and will be operated either with a single telescope or with up to four UTs, enabling an additional 1.5 magnitude gain. Thanks to its characteristics and ability of combining incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis of the variability of fundamental physical constants. In this paper, we will present the scientific objectives, the capabilities of ESPRESSO, the technical solutions for the system and its subsystems, enlightening the main differences between ESPRESSO and its predecessors. The project aspects of this facility are also described, from the consortium and partnership structure to the planning phases and milestones.
This paper presents the Espresso Exposure Meter (EM) implementation. ESPRESSO,1-3 the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will be installed on ESOs Very Large Telescope (VLT). The light coming from the Telescope through a Coud Focus4 of all the Four Telescope Units (UTs) will be collected by the Front End Unit that provides Field and Pupil stabilisation and injects the beams into the Spectrograph fibers.5 An advanced Exposure Meter system will be used to correct Radial Velocity (RV) obtained from the scientific spectrum for the Earth relative motion. In this work we will present the perfor mance of an innovative concept for the Exposure Meter system based on a Charge Coupled Device (CCD) with a chromatic approach for the calculation of the Mean Time of Exposure (MTE). The MTE is a crucial quantity used for the correction of RV for the Earth relative motion during the exposure. In particular, splitting the light in different chromatic channels on the CCD, we will probe for potential chromatic effects on the calculation of the MTE in each channel and how they could be used in order to perform the correction of RV. The paper is accompanied by a fully described numerical analysis that keeps into view a key performance evaluation for different stellar spectral types (B to M spectral main sequence classes).
Resolving power of spectrographs for large telescopes is generally limited by the maximum dimension of the dispersion
gratings. To overcome this limit, innovative optical configurations have been designed, starting from the ideas proposed
for CODEX. By properly combining pupil slicing and anamorphic magnification, a R~63’000-210’000 spectrograph has
been designed. Many different solutions were proposed during the early design phases, and a detailed trade off study has
been carried out to improve efficiency, manufacturability, and reduce risks and costs of the preliminary designs. We
present a full description of the optical design of the spectrograph after preliminary design review, together with
expected performances.
This paper presents the Espresso Front End mechanical and optical conguration. ESPRESSO, Echelle SPectro-graph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the efficiency of modern echelle
spectrograph design with extreme radial-velocity precision. It will be installed on ESO's VLT and it is expected
to achieve a gain of two magnitudes with respect to its predecessor HARPS. The instrumental radial-velocity
precision will also be improved to reach cm/s level. The Front End is a modular subsystem that collects the
light coming from the Coude Trains of all the Four Telescope Units (UT), provides Field and Pupil stabilization
via piezoelectric tip tilt devices and inject the beam into the Spectrograph fiber. The Front End will also inject
the calibration light coming from the calibration unit. There will be four Front End modules, one per UT.
A rotary Stage will provide the toggling between different observation mode: Single UT Ultra High resolution
(SUT-UHR), Single UT High resolution (SUT-HR) and multiple UTS Mid Rsolution (MUT-MR). The field and
pupil guiding is obtained through a reimaging system that elaborates the halo of the light out of the Injection
Fiber and a telescope pupil beacon. A dedicated guiding algorithm has been studied in order to provide proper
image stability even with faint objects (mv=20).
ESPRESSO, the VLT rocky exoplanets hunter, will combine the efficiency of modern echelle spectrograph with extreme
radial-velocity precision. It will be installed at Paranal on ESO's VLT in order to achieve a gain of two magnitudes with
respect to its predecessor HARPS, and the instrumental radial-velocity precision will be improved to reach 10 cm/s level.
We have constituted a Consortium of astronomical research institutes to fund, design and build ESPRESSO on behalf of
and in collaboration with ESO, the European Southern Observatory. The project has passed the preliminary design
review in November 2011. The spectrograph will be installed at the so-called "Combined Coudé Laboratory" of the
VLT, it will be linked to the four 8.2 meters Unit Telescopes (UT) through four optical "Coudé trains" and will be
operated either with a single telescope or with up to four UTs. In exchange of the major financial and human effort the
building Consortium will be awarded with guaranteed observing time (GTO), which will be invested in a common
scientific program. Thanks to its characteristics and the ability of combining incoherently the light of 4 large telescopes,
ESPRESSO will offer new possibilities in many fields of astronomy. Our main scientific objectives are, however, the search and characterization of rocky exoplanets in the habitable zone of quiet, near-by G to M-dwarfs, and the analysis
of the variability of fundamental physical constants. In this paper, we present the ambitious scientific objectives, the
capabilities of ESPRESSO, the technical solutions for the system and its subsystems, enlightening the main differences
between ESPRESSO and its predecessors. The project aspects of this facility are also described, from the consortium and
partnership structure to the planning phases and milestones.
ESPRESSO is a fiber-fed cross-dispersed echelle spectrograph which can be operated with one or up to 4 UT (Unit
Telescope) of ESO's Very Large Telescope (VLT). It will be located in the Combined-Coudé Laboratory (CCL) of the
VLT and it will be the first permanent instrument using a 16-m equivalent telescope. The ESPRESSO control software
and electronics are in charge of the control of all instrument subsystems: the four Coudé Trains (one for each UT), the
front-end and the fiber-fed spectrograph itself contained within a vacuum vessel. The spectrograph is installed inside a
series of thermal enclosures following an onion-shell principle with increasing temperature stability from outside to
inside. The proposed electronics architecture will use the OPC Unified Architecture (OPC UA) as a standard layer to
communicate with PLCs (Programmable Logical Controller), replacing the old Instrument Local Control Units (LCUs)
for ESO instruments based on VME technology. The instrument control software will be based on the VLT Control
Software package and will use the IC0 Field Bus extension for the control of the instrument hardware. In this paper we
present the ESPRESSO software architectural design proposed at the Preliminary Design Review as well as the control
electronics architecture.
This paper presents the Espresso Front End Guiding Algorithm. ESPRESSO, the Echelle SPectrograph for Rocky
Exoplanets and Stable Spectroscopic Observations, will be installed on ESO's Very Large Telescope (VLT). The
Front End (FE) is the subsystem that collects the light coming from the Coudè Trains of all the Four Telescope
Units (UTs), provides Field and Pupil stabilization via piezoelectric tip tilt devices and inject the beams into
the Spectrograph fibers. The field and pupil guiding is obtained through a re-imaging system that elaborates
the halo of the light out of the Injection Fiber and a telescope pupil beacon. The first guiding algorithm that we
evaluated splits the FP in four areas and computes the sum of the photon counting of each pixel in that area.
The unbalancing of the photon sums will give the centroid misalignment information that will be handled by the
Instrument Control Software (ICS). Different algorithms and controllers architectures have been evaluated and
implemented in order to select a strategy that enables the FE to guide up to 20 apparent magnitude in V band.
Since the beginning of the ESPRESSO (Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic
Observations) project, it has been recognized that the expected challenging scientific results can be achieved only if an
integrated view of the end-to-end operations is properly tackled. Hunting for rocky exoplanets and/or studying the
possible variations of physical constants requires not only a dedicated, state-of-the-art spectrograph in terms of hardware
and optics, but also a tailored observation strategy, data reduction pipeline and data analysis tools (ESPRESSO will be
the first ESO instrument for which a customized Data Analysis Software will be provided to the community by the
Consortium). In this paper we present the planned data flow system (DFS) for ESPRESSO as emerged after the
Preliminary Design Review held in November 2011. Main requirements in terms of observation strategy/preparation and
data reduction/analysis are analyzed and the corresponding foreseen (conceptual) design, able to fulfill them, discussed.
Eventually, peculiarities and challenges needed to adapt ESPRESSO DFS in the pre-existing ESO/VLT DFS framework
are outlined.
The first purpose of ESPRESSO is to develop a competitive, innovative high-resolution spectrograph to fully exploit the
potentiality of the Very Large Telescope (VLT) of the European Southern Observatory and to allow new science. It is
thus important to develop the VLT array concept bearing in mind the need to obtain the highest stability, while
preserving an excellent efficiency. This high-resolution ultra-stable spectrograph will be installed at the VLT Combined
Coudé Laboratory. A Coudé Train carries the light from the Nasmyth platforms to the Combined Coudé Laboratory,
where it feeds the spectrograph. Several concepts can be envisaged for the Coudé Train depending on the use of mirrors,
prisms and lenses or fibers or any of the possible combinations of these elements. Three concepts were selected for
analysis, one based on purely optical components and two other using fibers (with different lengths). These concepts
have different characteristics in terms of efficiency, stability, complexity, and cost. The selection of the baseline concept
took into account all these issues. In this paper, we present for each concept the optical setups, their opto-mechanical
implementation and analyze the expected throughput efficiency budget, and we also detail the current baseline concept.
ESPRESSO is a high-resolution, highly stable spectrograph for the VLT. It will inherit and enhance most capabilities
from HARPS and UVES, combining both stability and efficiency. The main science driver will be the detection and
characterization of Earth-like planets, but many additional science cases will benefit from its highly stable spectroscopic
observations. The facility will be installed at the combined Coudé focus of the VLT and may be linked with any of the
four UT telescopes, enabling thus a great flexibility for the efficient use of telescope time. This particularity makes the
interface with the VLT more complex than for an instrument fed by a single telescope. It impacts on the complexity of
the relationship between the consortium providing the instrument and ESO, the customer. The targeted high RV accuracy
requires very high performances in stability and resolution, which in turn require adequate technical solutions at several
levels. This paper describes the instrument system and subsystems, enlightening the most valuable differences between
ESPRESSO and it's predecessors, the details of the project, entering now the design phases, the ESPRESSO consortium,
composed of Italian, Portuguese, Spanish and Swiss institutes, and the relationship between the consortium and ESO.
CODEX is the proposed ultra-stable optical high-resolution spectrograph for the E-ELT, which will use novel Laser
Comb calibration techniques and an innovative design to open a new era for precision spectroscopy. With its unique
combination of light-collecting power and precision, CODEX will make it possible to directly measure the acceleration
of the Universe by monitoring the cosmological redshift drift of spectroscopic features at cosmological distances.
CODEX will also allow the assembly of the first sizeable sample of earth-like planets in the habitable zones of their stars
with the radial velocity technique. CODEX will take this technique to the level of cm/sec radial velocity stability - a
factor of about 20 improvement compared to current instruments. These are two of the scientific results anticipated for
CODEX, which will be complemented by a wide range of spectacular science in stellar, galactic and extra-galactic
Astronomy as well as Fundamental Physics. All the critical technology items are available or (as for the Laser Frequency
Comb) are in an advanced state of testing. CODEX is located at the E-ELT coudé focus that will cover the visible range
from 370 to 710 nm and provide a resolving power R~120000 with an aperture of 0.8 arcseconds in the sky.
ESPRESSO, a very high-resolution, high-efficiency, ultra-high stability, fiber-fed, cross-dispersed echelle spectrograph
located in the Combined-Coudé focus of the VLT, has been designed to detect exo-planets with unprecedented radial
velocity accuracies of 10 cm/sec over 20 years period. To increase spectral resolution, an innovative pupil slicing
technique has been adopted, based onto free-form optics. Anamorphism has been added to increase resolution while
keeping the physical size of the echelle grating within reasonable limits. Anamorphic VPH grisms will help to decrease
detector size, while maximizing efficiency and inter-order separation. Here we present a summary of the optical design
of the spectrograph and of expected performances.
ESPRESSO, the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations, will combine the
efficiency of modern echelle spectrograph design with extreme radial-velocity precision. It will be installed on ESO's
VLT in order to achieve a gain of two magnitudes with respect to its predecessor HARPS, and the instrumental radialvelocity
precision will be improved to reach cm/s level. Thanks to its characteristics and the ability of combining
incoherently the light of 4 large telescopes, ESPRESSO will offer new possibilities in various fields of astronomy. The
main scientific objectives will be the search and characterization of rocky exoplanets in the habitable zone of quiet, nearby
G to M-dwarfs, and the analysis of the variability of fundamental physical constants. We will present the ambitious
scientific objectives, the capabilities of ESPRESSO, and the technical solutions of this challenging project.
A number of outstanding scientific problems require a high resolution, visual spectrograph at the E-ELT. Measuring the
dynamics of the universe, finding earth-like planets with radial velocity techniques, determining the chemical evolution
of the intergalactic medium and if physical constants varied in the past, all require a superior capability of measuring
exceedingly small Doppler shifts. We have started a Phase A study for CODEX at the E-ELT. We present here the
scientific cases, the requirements, the basic technical choices and trade offs, as well as a couple of design under
evaluation. We aim at a super stable instrument, capable of obtaining a radial velocity precision of 2 cm/sec over several
decades. It will be located at the coude focus. The design will make use of anamorphosis, pupil slicing, slanted VPH
gratings and a novel calibration system based on laser frequency combs. Several CODEX-related R&D activities are
running, and, in addition, a Call for Proposal for a precursor at the VLT has been issued.
An analysis of the galaxy evolution from deep multicolor imaging of optically and infrared selected galaxies is presented and compared with current models of galaxy formation and evolution. A very deep K=20-23) sample of optically and infrared selected galaxies from ESO/VLT and HST surveys like the HDF South, Chandra Deep Field, NTT Deep Field is being analyzed. First results are shown in terms of the high redshift rest frame UV luminosity density and rest frame blue luminosity function and compared with predictions of CDM hierarchical models for galaxy formation and evolution. The observations show an excess of bright sources at very high redshifts 5<z<6 respect to the expectations of the CDM models. At the same time the models predict too many dwarfs especially at intermediate and high redshifts. Possible explanations for these discrepancies are briefly discussed.
UVES is a dual beam echelle spectrograph installed at the Nasmyth focus of the UT2 telescope of the ESO VLT since October 1999. It can reach a resolution of 80000 and 115000 in the blue and red arm, respectively. The instrument is characterized by great stability and high efficiency. The smooth operation of both the new telescope and instrument has lead to a remarkable number of highly interesting scientific observations during commissioning. Examples of scientific work on these data are presented to illustrate the unique UV efficiency, the resolving power and high S/N capability and far red efficiency.
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