The ESO Extremely Large Telescope (ELT) has been in construction since 2014. In parallel with the construction of the telescope, ESO has entered into agreements with consortia in the ESO member states to build the first instruments for that telescope. To meet the telescope science goals, the ambitious instrument plan includes two instruments for first light: an optical to near-infrared integral field spectrograph with a dedicated adaptive optics system (HARMONI) and a near-infrared camera with simple spectrograph (MICADO) behind a multi-conjugate adaptive optics module (MAORY). The next instrument will be a mid-infrared imager and spectrograph (METIS). Plans to follow this first suite of instruments include a high-resolution spectrograph (HIRES) and a multi-object spectrograph (MOSAIC). Technology development is underway to prepare for building the ELT Planetary Camera and Spectrograph. An overview of the telescope and its instruments is given.
The long commissioning of the Adaptive Optics Facility (AOF) project has been completed shortly after this conference, providing AO correction to two Very Large Telescope (VLT) foci supported by an adaptive secondary mirror and four laser guide stars. Four AO modes are delivered: a Single Conjugate AO (SCAO) system for commissioning purpose, wide field and medium field Ground Layer AO (GLAO) for seeing improvement and narrow field Laser Tomography AO (LTAO) for ultimate performance. This paper intends to describe the implemented AO baseline and to highlight the most relevant results and lessons learned. In particular, it will address the control and reconstruction strategy, the wavefront sensing baseline and the online telemetry used to optimize the system online, estimate the turbulence profile and calibrate the misregistrations. Focusing on the LTAO mode, we will describe the tomography optimization, by exploring the reconstruction parameter space. Finally, on sky performance results will be presented both in terms of strehl ratio and limiting magnitude.
In this paper we will report on the status of the instrumentation project for the European Southern Observatory's Extremely Large Telescope (ELT). Three instruments are in the construction phase: HARMONI, MICADO and METIS. The multi-conjugate adaptive optics system for MICADO, MAORY, is also under development. Preliminary Design Reviews of all of these systems are planned to be completed by mid-2019. The construction of a laser tomographic module for HARMONI is part of "Phase 2" of the ELT: the design has been advanced to Preliminary Design level in order to define the interface to the HARMONI spectrograph. Preparations for the next instruments have also been proceeding in parallel with the development of these instruments. Conceptual design studies for the multi-object spectrograph MOSAIC, and for the high resolution spectrograph HIRES have been completed and reviewed. We present the current design of each of these instruments and will summarise the work ongoing at ESO related to their development.
A suite of seven instruments and associated AO systems have been planned as the "E-ELT Instrumentation Roadmap". Following the E-ELT project approval in December 2014, rapid progress has been made in organising and signing the agreements for construction with European universities and institutes. Three instruments (HARMONI, MICADO and METIS) and one MCAO module (MAORY) have now been approved for construction. In addition, Phase-A studies have begun for the next two instruments - a multi-object spectrograph and high-resolution spectrograph. Technology development is also ongoing in preparation for the final instrument in the roadmap, the planetary camera and spectrograph. We present a summary of the status and capabilities of this first set of instruments for the E-ELT.
HARMONI is the E-ELT’s first light visible and near-infrared integral field spectrograph. It will provide four different spatial scales, ranging from coarse spaxels of 60 × 30 mas best suited for seeing limited observations, to 4 mas spaxels that Nyquist sample the diffraction limited point spread function of the E-ELT at near-infrared wavelengths. Each spaxel scale may be combined with eleven spectral settings, that provide a range of spectral resolving powers (R ~3500, 7500 and 20000) and instantaneous wavelength coverage spanning the 0.5 – 2.4 μm wavelength range of the instrument. In autumn 2015, the HARMONI project started the Preliminary Design Phase, following signature of the contract to design, build, test and commission the instrument, signed between the European Southern Observatory and the UK Science and Technology Facilities Council. Crucially, the contract also includes the preliminary design of the HARMONI Laser Tomographic Adaptive Optics system. The instrument’s technical specifications were finalized in the period leading up to contract signature. In this paper, we report on the first activity carried out during preliminary design, defining the baseline architecture for the system, and the trade-off studies leading up to the choice of baseline.
Sky-coverage in laser-assisted AO observations largely depends on the system's capability to guide on the faintest natural guide-stars possible. Here we give an up-to-date status of our natural guide-star processing tailored to the European-ELT's visible and near-infrared (0.47 to 2.45 μm) integral field spectrograph — Harmoni.
We tour the processing of both the isoplanatic and anisoplanatic tilt modes using the spatio-angular approach whereby the wavefront is estimated directly in the pupil plane avoiding a cumbersome explicit layered estimation on the 35-layer profiles we're currently using.
Taking the case of Harmoni, we cover the choice of wave-front sensors, the number and field location of guide-stars, the optimised algorithms to beat down angular anisoplanatism and the performance obtained with different temporal controllers under split high-order/low-order tomography or joint tomography. We consider both atmospheric and far greater telescope wind buffeting disturbances. In addition we provide the sky-coverage estimates thus obtained.
In this paper we present numerical simulations and an initial design for a visible MCAO system for the VLT-UT4 telescope. The proposed concept takes great advantage of the existing HW developed for the Adaptive Optics Facility (AOF) at the VLT-UT4, in particular the 4x20W Toptica lasers and the adaptive secondary mirror with 1170 actuators. The mentioned units makes the VLT-AOF a unique facility to develop a second generation AO system aiming to provide corrected FoV at short wavelength. In particular the flux provided by the four lasers steerable on sky and the high density of actuators (20cm equivalent on M1) provides the temporal bandwidth and the spatial sampling to push the correction down to the visible wavelengths. In addition to this the request of a reasonable size corrected FoV with uniform performance calls for an MCAO system. For such reason here we propose to complement the AOF with post-focal DMs that together with the VLT DSM can provide a corrected FoV of roughly 20/30 arcsec diameter size. An additional challenge for the system is the provided a large sky coverage. Such condition comes from the efficiency of LO wavefront sensors that use field NGS. The presented simulations give some first results for (a) the achieved performance at visible wavelength 0.4-0.9 um as a function of DMs and tip tilt NGSs characteristics (b) the achieved system sky coverage after. Pushing performance toward visible wavelengths calls for embedded and efficient post-processing methods. Being able to capture short-exposure science images (with the trade-off on noise and overheads), would allow retrieving the ultimate performance by compensating the residual turbulence aberrations left over by the AO system. Considerations about advanced analysis tools that may potentially relax the system constraints are discussed. Finally the paper presents a conceptual arrangement for the opto-mechanics of the considered AO module including the additional DMs and wavefront sensors.
GALACSI is the Adaptive Optics (AO) module that will serve the MUSE Integral Field Spectrograph. In Wide Field Mode it will enhance the collected energy in a 0.2”×0.2” pixel by a factor 2 at 750 nm over a Field of View (FoV) of 1’×1’ using the Ground Layer AO (GLAO) technique. In Narrow Field Mode, it will provide a Strehl Ratio of 5% (goal 10%) at 650 nm, but in a smaller FoV (7.5”×7.5” FoV), using Laser Tomography AO (LTAO). Before being ready for shipping to Paranal, the system has gone through an extensive testing phase in Europe, first in standalone mode and then in closed loop with the DSM in Europe. After outlining the technical features of the system, we describe here the first part of that testing phase and the integration with the AOF ASSIST (Adaptive Secondary Setup and Instrument Stimulator) testbench, including a specific adapter for the IRLOS truth sensor. The procedures for the standalone verification of the main system performances are outlined, and the results of the internal functional tests of GALACSI after full integration and alignment on ASSIST are presented.
HARMONI is a visible and NIR integral field spectrograph, providing the E-ELT’s core spectroscopic capability at first light. HARMONI will work at the diffraction limit of the E-ELT, thanks to a Classical and a Laser Tomographic AO system. In this paper, we present the system choices that have been made for these SCAO and LTAO modules. In particular, we describe the strategy developed for the different Wave-Front Sensors: pyramid for SCAO, the LGSWFS concept, the NGSWFS path, and the truth sensor capabilities. We present first potential implementations. And we asses the first system performance.
MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument built for ESO (European Southern
Observatory). The MUSE project is supported by a European consortium of 7 institutes.
After the finalisation of its integration in Europe, the MUSE instrument has been partially dismounted and shipped to
the VLT (Very Large Telescope) in Chile. From October 2013 till February 2014, it has then been reassembled, tested
and finally installed on the telescope its final home. From there it collects its first photons coming from the outer limit
of the visible universe.
This critical moment when the instrument finally meets its destiny is the opportunity to look at the overall outcome of
the project and the final performance of the instrument on the sky. The instrument which we dreamt of has become
reality. Are the dreamt performances there as well?
These final instrumental performances are the result of a step by step process of design, manufacturing, assembly, test
and integration. Now is also time to review the path opened by the MUSE project. What challenges were faced during
those last steps, what strategy, what choices did pay off? What did not?
MUSE Instrumentation Software is the software devoted to the control of the Multi-Unit Spectroscopic Explorer
(MUSE), a second-generation VLT panoramic integral-field spectrograph instrument, installed at Paranal in January
2014. It includes an advanced and user-friendly GUI to display the raw data of the 24 detectors, as well as the on-line
reconstructed images of the field of view allowing users to assess the quality of the data in quasi-real
time. Furthermore, it implements the slow guiding system used to remove effects of possible differential drifts between
the telescope guide probe and the instrument, and reach high image stability (<0.03 arcsec RMS stability).
In this paper we report about the software design and describe the developed tools that efficiently support astronomers
while operating this complex instrument at the telescope.
GALACSI is the Adaptive Optics (AO) modules of the ESO Adaptive Optics Facility (AOF) that will correct the wavefront delivered to the MUSE Integral Field Spectrograph. It will sense with four 40×40 subapertures Shack-Hartmann wavefront sensors the AOF 4 Laser Guide Stars (LGS), acting on the 1170 voice-coils actuators of the Deformable Secondary Mirror (DSM). GALACSI has two operating modes: in Wide Field Mode (WFM), with the four LGS at 64” off axis, the collected energy in a 0.2”×0.2” pixel will be enhanced by a factor 2 at 750 nm over a Field of View (FoV) of 1’×1’ using the Ground Layer AO (GLAO) technique. The other mode, the Narrow Field Mode (NFM), provides an enhanced wavefront correction (Strehl Ratio (SR) of 5% (goal 10%) at 650 nm) but in a smaller FoV (7.5”×7.5”), using Laser Tomography AO (LTAO), with the 4 LGS located closer, at 10” off axis. Before being shipped to Paranal, GALACSI will be first integrated and fully tested in stand-alone, and then moved to a dedicated AOF facility to be tested with the DSM in Europe. At present the module is fully assembled, its main functionalities have been implemented and verified, and AO system tests with the DSM are starting. We present here the main system features and the results of the internal functional tests of GALACSI.
MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument, built for ESO (European Southern
Observatory) and dedicated to the VLT (Very Large Telescope). This instrument is an innovative integral field
spectrograph (1x1 arcmin2 Field of View), operating in the visible wavelength range, from 465 nm to 930 nm. The
MUSE project is supported by a European consortium of 7 institutes.
After the finalisation of its integration and test in Europe validated by its Preliminary Acceptance in Europe, the MUSE
instrument has been partially dismounted and shipped to the VLT (Very Large Telescope) in Chile. From October 2013
till February 2014, it has then been reassembled, tested and finally installed on the telescope its final home. From there
it will collect its first photons coming from the outer limit of the visible universe.
To come to this achievement, many tasks had to be completed and challenges overcome. These last steps in the project
life have certainly been ones of the most critical. Critical in terms of risk, of working conditions, of operational
constrains, of schedule and finally critical in terms of outcome: The first light and the final performances of the
instrument on the sky.
CUBES is a high-efficiency, medium-resolution (R ≃ 20, 000) spectrograph dedicated to the “ground based UV”
(approximately the wavelength range from 300 to 400nm) destined for the Cassegrain focus of one of ESO’s VLT
unit telescopes in 2018/19. The CUBES project is a joint venture between ESO and Instituto de Astronomia,
Geof´ısica e Ciˆencias Atmosf´ericas (IAG) at the Universidade de S˜ao Paulo and the Brazilian Laborat´orio Nacional
de Astrofs´ıca (LNA). CUBES will provide access to a wealth of new and relevant information for stellar as well as
extra-galactic sources. Principle science cases include the study of heavy elements in metal-poor stars, the direct
determination of carbon, nitrogen and oxygen abundances by study of molecular bands in the UV range and the
determination of the Beryllium abundance as well as the study of active galactic nuclei and the inter-galactic
medium. With a streamlined modern instrument design, high efficiency dispersing elements and UV-sensitive
detectors, it will enable a significant gain in sensitivity over existing ground based medium-high resolution
spectrographs enabling vastly increased sample sizes accessible to the astronomical community. We present here
a brief overview of the project, introducing the science cases that drive the design and discussing the design
options and technological challenges.
MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument built for ESO (European Southern
Observatory) to be installed in Chile on the VLT (Very Large Telescope). The MUSE project is supported by a
European consortium of 7 institutes.
After the critical turning point of shifting from the design to the manufacturing phase, the MUSE project has now
completed the realization of its different sub-systems and should finalize its global integration and test in Europe.
To arrive to this point many challenges had to be overcome, many technical difficulties, non compliances or
procurements delays which seemed at the time overwhelming. Now is the time to face the results of our organization, of
our strategy, of our choices. Now is the time to face the reality of the MUSE instrument.
During the design phase a plan was provided by the project management in order to achieve the realization of the
MUSE instrument in specification, time and cost. This critical moment in the project life when the instrument takes
shape and reality is the opportunity to look not only at the outcome but also to see how well we followed the original
plan, what had to be changed or adapted and what should have been.
MUSE (Multi Unit Spectroscopic Explorer) is an integral-field spectrograph which will be mounted on the Very Large
Telescope (VLT). MUSE is being built for ESO by a European consortium under the supervision of the Centre de
Recherche Astrophysique de Lyon (CRAL).
In this context, CRAL is responsible for the development of dedicated software to help MUSE users prepare and submit
their observations. This software, called MUSE-PS, is based on the ESO SkyCat tool that combines visualization of
images and access to catalogs and archive data for astronomy. MUSE-PS has been developed as a plugin to SkyCat to
add new features specific to MUSE observations.
In this paper, we present the MUSE observation preparation tool itself and especially its specific functionalities:
definition of the center of the MUSE field of view and orientation, selection of the VLT guide star for the different
modes of operations (Narrow Field Mode or Wide Field Mode, with or without AO). We will also show customized
displays for MUSE (zoom on specific area, help with MUSE mosaïcing and generic offsets, finding charts …).
GALACSI is one of the Adaptive Optics (AO) systems part of the ESO Adaptive Optics Facility (AOF). It will use the
VLT 4-Laser Guide Stars system, high speed and low noise WaveFront Sensor cameras (<1e-, 1000Hz) the
Deformable Secondary Mirror (DSM) and the SPARTA Real Time Computer to sharpen images and enhance faint
object detectability of the MUSE Instrument. MUSE is an Integral Field Spectrograph working at wavelengths from
465nm to 930nm. GALACSI implements 2 different AO modes; in Wide Field Mode (WFM) it will perform Ground
Layer AO correction and enhance the collected energy in a 0.2" by 0.2" pixel by a factor 2 at 750nm over a Field of
View (FoV) of 1' by 1'. The 4 LGSs and one tip tilt reference star (R-mag <17.5) are located outside the MUSE FoV.
Key requirements are to provide this performance and a very good image stability for a 1hour long integration time. In
Narrow Field Mode (NFM) Laser Tomography AO will be used to reconstruct and correct the turbulence for the center
field using the 4 LGSs at 15" off axis and the Near Infra Red (NIR) light of one reference star on axis for tip tilt and
focus sensing. In NFM GALACSI will provide a moderate Strehl Ratio of 5% (goal 10%) at 650nm. The NFM hosts
several challenges and many subsystems will be pushed to their limits. The opto mechanical design and error budgets
of GALACSI is described here.
MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument developed for ESO (European Southern
Observatory) to be installed on the VLT (Very Large Telescope) in year 2012. The MUSE project is supported by a
European consortium of 7 institutes. After a successful Final Design Review the project is now facing a turning point
which consist in shifting from design to manufacturing, from calculation to test, ... from dream to reality.
At the start, many technical and management challenges were there as well as unknowns. They could all be derived of
the same simple question: How to deal with complexity? The complexity of the instrument, of the work to de done, of
the organization, of the interfaces, of financial and procurement rules, etc.
This particular moment in the project life cycle is the opportunity to look back and evaluate the management methods
implemented during the design phase regarding this original question. What are the lessons learn? What has been
successful? What could have been done differently? Finally, we will look forward and review the main challenges of the
MAIT (Manufacturing Assembly Integration and Test) phase which has just started as well as the associated new
processes and evolutions needed.
The X-shooter data reduction pipeline, as part of the ESO-VLT Data Flow System, provides recipes for Paranal
Science Operations, and for Data Product and Quality Control Operations at Garching headquarters. At Paranal,
it is used for the quick-look data evaluation. The pipeline recipes can be executed either with EsoRex at the
command line level or through the Gasgano graphical user interface. The recipes are implemented with the ESO
Common Pipeline Library (CPL).
X-shooter is the first of the second generation of VLT instruments. It makes possible to collect in one shot
the full spectrum of the target from 300 to 2500 nm, subdivided in three arms optimised for UVB, VIS and NIR
ranges, with an efficiency between 15% and 35% including the telescope and the atmosphere, and a spectral
resolution varying between 3000 and 17,000. It allows observations in stare, offset modes, using the slit or an
IFU, and observing sequences nodding the target along the slit.
Data reduction can be performed either with a classical approach, by determining the spectral format via
2D-polynomial transformations, or with the help of a dedicated instrument physical model to gain insight on the
instrument and allowing a constrained solution that depends on a few parameters with a physical meaning.
In the present paper we describe the steps of data reduction necessary to fully reduce science observations in
the different modes with examples on typical data calibrations and observations sequences.
The data reduction pipeline for the VLT 2nd generation instrument X-Shooter uses a physical model to determine
the optical distortion and derive the wavelength calibration. The parameters of this model describe the positions,
orientations, and other physical properties of the optical components in the spectrograph. They are updated
by an optimisation process that ensures the best possible fit to arc lamp line positions. ESO Quality Control
monitors these parameters along with all of the usual diagnostics. This enables us to look for correlations between
inferred physical changes in the instrument and, for example, instrument temperature sensor readings.
We have developed a physical model of the VLT 2nd generation instrument X-shooter. The parameters of this
model, that describe the positions, orientations and other physical properties of the optical components in the
spectrograph, are continually updated by an optimisation process that ensures the best possible fit to arc lamp
line positions in calibration exposures. Besides its use in driving the wavelength calibration in the data reduction
pipeline, the physical model provides us with an insight into physical changes in the optical components and the
possibility to correlate these with changing instrument orientation. By utilising a continually growing database
of automatic flexure compensation exposures that cover a wide range of instrument orientations, we are able to
investigate flexure in terms of physical model parameters.
In this paper we present a brief status report on the conceptual designs of the instruments and adaptive optics modules
that have been studied for the European Extremely Large Telescope (E-ELT). In parallel with the design study for the
42-m telescope, ESO launched 8 studies devoted to the proposed instruments and 2 for post-focal adaptive optics
systems. The studies were carried out in consortia of ESO member state institutes or, in two cases, by ESO in
collaboration with external institutes. All studies have now been successfully completed. The result is a powerful set of
facility instruments which promise to deliver the scientific goals of the telescope.
The aims of the individual studies were broad: to explore the scientific capabilities required to meet the E-ELT science
goals, to examine the technical feasibility of the instrument, to understand the requirements placed on the telescope
design and to develop a delivery plan. From the perspective of the observatory, these are key inputs to the development
of the proposal for the first generation E-ELT instrument suite along with the highest priority science goals and
budgetary and technical constraints. We discuss the lessons learned and some of the key results of the process.
X-shooter is the first second-generation instrument newly commissioned a the VLT. It is a high efficiency single
target intermediate resolution spectrograph covering the range 300 - 2500 nm in a single shot. We summarize
the main characteristics of the instrument and present its performances as measured during commissioning and
the first months of science operations.
Summary: The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field
spectrograph currently in manufacturing, assembly and integration phase. MUSE has a field of 1x1 arcmin2 sampled at
0.2x0.2 arcsec2 and is assisted by the VLT ground layer adaptive optics ESO facility using four laser guide stars. The
instrument is a large assembly of 24 identical high performance integral field units, each one composed of an advanced
image slicer, a spectrograph and a 4kx4k detector. In this paper we review the progress of the manufacturing and report
the performance achieved with the first integral field unit.
The European Southern Observatory (ESO) is conducting a phase B study of a European Extremely Large Telescope (E-ELT).
The baseline concept foresees a 42m primary, 5 mirror adaptive telescope with two of the mirrors giving the
possibility of very fast correction of the atmospheric turbulence. In parallel to the telescope study, ESO is coordinating
8 studies of instruments and 2 of post-focus Adaptive Optics systems, carried out in collaboration with Institutes in the
member states. Scope of the studies, to be completed by 1Q 2010, is to demonstrate that the high priority scientific goals of
the E-ELT project can be achieved with feasible and affordable instruments. The main observing modes being considered
are: NIR wide field imaging and spectroscopy to the diffraction limit or with partial correction of the atmospheric seeing;
high spectral resolution, high stability visible spectroscopy; high contrast, diffraction limited imaging and spectroscopy; DL
mid-infrared imaging and spectroscopy. The status of the 8 current studies is presented.
We present a project aimed at establishing a set of 12 spectro-photometric standards over a wide wavelength range from
320 to 2500 nm. Currently no such set of standard stars covering the near-IR is available. Our strategy is to extend the
useful range of existing well-established optical flux standards into the near-IR by means of integral field spectroscopy
with SINFONI at the VLT combined with state-of-the-art white dwarf stellar atmospheric models. As a solid reference,
we use two primary HST standard white dwarfs. This ESO "Observatory Programme" has been collecting data since
February 2007. The analysis of the data obtained in the first year of the project shows that a careful selection of the
atmospheric windows used to measure fluxes and the stability of SINFONI make it possible to achieve an accuracy of 3-
6% depending on the wavelength band and stellar magnitude, well within our original goal of 10% accuracy. While this
project was originally tailored to the needs of the wide wavelength range (320-2500 nm) of X-shooter on the VLT, it will
also benefit any other near-IR spectrographs, providing a huge improvement over existing flux calibration methods.
We have developed a physical model of the VLT 2nd generation instrument X-shooter for use in wavelength
calibration. We describe here the model concept, its use during the development of the data reduction software
and the initial alignment of the spectrograph in the laboratory and the optimisation of the model to fit early
We have studied the properties of wavelength calibration sources for the near-IR (NIR: 1000-2500 nm) arm of X-shooter.
In a novel approach we are combining laboratory measurements from a Fourier Transform Spectrometer (FTS)
and literature data with corresponding simulated data derived from a physical model of X-shooter. The sources studied
are pen ray lamps filled with the noble gases Ne, Ar, Kr, and Xe and Th-Ar hollow cathode lamps. As a product we
provide a quantitative order by order analysis of the expected properties of the calibration lamps during X-shooter
operations. The analysis accounts for blending of lines and makes realistic assumptions about the dynamic range
available in a typical wavelength calibration exposure. Based on our study we recommend the use of Ne, Kr, and Ar as
the best three lamp combination for X-shooter calibration. A detailed comparison between the predicted and actual
performance of the calibration system has been started as part of the X-shooter testing and validation phase and first
results are very promising. To our knowledge this is the first time that such a detailed and quantitative analysis of a
calibration system has been done prior to the operation of the instrument. The combination of laboratory measurements
and instrument modeling provides a powerful tool for future instrument development.
We present the current state of the Data Reduction Software (DRS) being developed at APC, Paris Observatory,
Amsterdam University and ESO for the X-shooter echelle spectrograph. X-shooter is the first VLT second
generation instrument, which will have its first light during the fall of the current year and will be available to
the astronomical community starting April 2009. The DRS will be fully integrated in the ESO VLT data flow
environment and it will use the ESO Common Pipeline Library. X-shooter data have two main characteristics,
on the one hand the exceptionally wide band (0.3 - 2.4 micron) covered in a single exposure, and on the other
hand the spectral format with highly curved orders and tilted lines. After a brief description of the reduction
process, the main results obtained up to now on simulated and laboratory data are reported. In particular the
precision of wavelength calibration and sky subtraction are discussed.
X-shooter is a new high-efficiency spectrograph observing the complete spectral range of 300-2500 nm in a single
exposure, with a spectral resolving power R>5000. The instrument will be located at the Cassegrain focus of one of the
VLT UTs and consists of three spectrographs: UV, VIS and Near-IR. This paper addresses the design, hardware
realization and performance of the Near-IR spectrograph of the X-Shooter instrument and its components.
Various optical, mechanical and cryogenic manufacturing and verification techniques are discussed. The cryogenic
performance of replicated light weight gratings is presented. Bare aluminium mirrors are produced and polished to
optical quality to preserve high shape accuracy at cryogenic conditions. Their manufacturing techniques and
performance are both discussed. The cryogenic collimator and dispersion boxes, on which the optical components are
mounted, feature integrated baffles for improved stiffness and integrated leaf springs to reduce tension on optical
components, thereby challenging 5 axis simultaneous CNC milling capabilities. ASTRON Extreme Light Weighting is
used for a key component to reduce the flexure of the cryogenic system; some key numbers and unique manufacturing
experience for this component are presented. The method of integrated system design at cryogenic working temperatures
and the resulting alignment-free integration are evaluated. Finally some key lab test results for the complete NIR
spectrograph are presented.
X-shooter is a single target spectrograph for the Cassegrain focus of one of the VLT UTs where it will start to operate in
2008. The instrument covers in a single exposure the spectral range from the UV to the K' band. It is designed to
maximize the sensitivity in this spectral range through the splitting in three arms with optimized optics, coatings,
dispersive elements and detectors. It operates at intermediate resolutions (R=4000-14000, depending on wavelength and
slit width) with fixed echelle spectral format (with prism cross-dispersers) in the three arms. The project has completed
the Final Design Review in June 2006. In this status report, the overall concept is summarized and new results on the
dichroics, the active flexure compensation system, the operation modes and the expected performance are given. The
instrument is being built by a Consortium of Institutes from Denmark, France, Italy and the Netherlands in collaboration
with ESO. When in operation, its wide spectral range observing capability will be unique at very large telescopes.
We present the Data Reduction Software (DRS) being developed at APC, Paris Observatory, Amsterdam University
and ESO for the X-shooter echelle spectrograph. X-shooter is the first VLT second generation instrument,
expected to be operational in 2008. The DRS will be fully integrated in the ESO VLT system and it will use the
ESO Common Pipeline Library. We discuss the data reduction related to slit and IFU observations. X-shooter
data have two main characteristics, on the one hand the exceptionally wide band (0.3-2.4 μm) covered in a single
exposure, and on the other hand the spectral format with highly curved orders and tilted lines. The reduction
process is described and the critical issues related to the above characteristics, notably the sky subtraction, the
optimal extraction, and the construction of 1D/2D/3D output products, are addressed. Some aspects of the
spectrophotometric calibration are also discussed.
X-Shooter is the first 2nd generation instrument to be installed at Paranal early 2008. It is a single target spectrograph covering in a single exposure a wide spectral range from the UV to the K' band with maximum sensitivity. Another key feature of the instrument is its fast response, obtained by making it simple and easy to operate. Compared to other big VLT instruments X-Shooter has a relatively small number of moving functions, but nevertheless the requirements on the whole instrument software are quite demanding. In order to cover the wide spectral range with high efficiency, the instrument is split into three different arms, one being cryogenically cooled. The high level coordinating software architecture provides all the facilities for parallel operation with the maximum achievable level of synchronicity. Low level X-Shooter requirements are also quite stringent, since to compensate for slit misalignments among the three arms, an active piezoelectric actuator system is envisaged. The low-level architecture, besides the typical control of single devices (like motors, sensors and lamps), handles the required real-time operations. The software integration and test is also an issue, being X-Shooter a collaborative effort among several institutes spread around Europe. The whole instrument software architecture is presented here, entering in details into its main modules such as the instrument control software, the observation software and the observing templates structure and their integration in the VLT software environment.