The FORS Upgrade project (FORS-Up) aims at bringing a new life to the highly demanded workhorse instrument attached to ESO’s Very Large Telescope (VLT). FORS2 is a multimode optical instrument, which started regular science operations in 2000 and since then, together with its twin, FORS1, has been one of the most demanded and most productive instruments of the VLT. In order to ensure that a FORS shall remain operational for at least another 15 years, an upgrade has been planned. This is required as FORS2 is using technology and software that is now obsolete and cannot be put and maintained to the standards in use at the Observatory. The project – carried out as a collaboration between ESO and INAF– Astronomical Observatory of Trieste – aims at bringing to the telescope in 2023/2024 a refurbished instrument with a new scientific detector, an upgrade of the instrument control software and electronics, a new calibration unit, as well as additional filters and grisms. The new FORS will also serve as a test bench for the Extremely Large Telescope (ELT) standard technologies (among them the use of programmable logic controllers and of the features of the ELT Control Software). The project aims at minimising the downtime of the instrument by performing the upgrade on the currently decommissioned instrument FORS1 and retrofitting the Mask Exchange Unit and polarisation optics from FORS2 to FORS1.
With more than 200 scientists and engineers involved, the design and manufacture of the 4MOST instrument, a secondgeneration spectroscopic instrument built for ESO's 4.1-metre VISTA telescope, is a challenge requiring the implementation of an efficient quality assurance strategy during each project phase (i.e., design, manufacture, test, installation, and operation), and including the maintenance. This paper introduces the 4MOST product assurance approach used by the project to make sure that 4MOST will comply with all necessary quality and safety requirements over the whole instrument’s lifetime of 15 years. For quality assurance, the guiding principles are mainly given by the ISO 10007:2017 and ISO 9001:2015 quality management standards. Related to safety, 4MOST design and manufacture complies not only with the essential safety requirements from the European Union New Approach Directives (CE Marking Directives), but also with the additional requirements coming from the ESO Safety Policy, issued by the ESO Management for ESO-wide application. The implementation of the 4MOST project’s Quality Assurance and Configuration Management is described in detail in the paper.
Transmission spectroscopy facilitates the detection of molecules and/or clouds in the atmospheres of exoplanets. Such studies rely heavily on space-based or large ground-based observatories, as one needs to perform time-resolved, high signal-to-noise spectroscopy. The FORS2 instrument at ESO's Very Large Telescope is the obvious choice for performing such studies, and was indeed pioneering the field in 2010. After that, however, it was shown to suffer from systematic errors caused by the Longitudinal Atmospheric Dispersion Corrector (LADC). This was successfully addressed, leading to a renewed interest for this instrument as shown by the number of proposals submitted to perform transmission spectroscopy of exoplanets. We present here the context, the problem and how we solved it, as well as the recent results obtained. We finish by providing tips for an optimum strategy to do transmission spectroscopy with FORS2, in the hope that FORS2 may become the instrument of choice for ground-based transmission spectroscopy of exoplanets.
KEYWORDS: Observatories, Quality systems, Telescopes, Document management, Control systems, Nomenclature, Process control, Optical instrument design, Calibration, Data archive systems
An initiative is under way at ESO Headquarters to optimise operations, in particular in the engineering, technical and associated management areas. A systematic approach to strengthen the operating processes is in preparation, starting with a mapping of the extensive existing process network. Processes identified as sufficiently important and complex to merit an in-depth analysis will be properly specified and their implementation optimised to strike a sensible balance between organisational overhead (documentation) and efficiency. By applying methods and tools tried and tested in industry we expect to achieve a more unified approach to address recurrent tasks. This will enable staff to concentrate more on new challenges and improvement and avoid spending effort on issues already resolved in the past.
MATISSE is the second-generation mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This new interferometric instrument will allow significant advances by opening new avenues in various fundamental research fields: studying the planet-forming region of disks around young stellar objects, understanding the surface structures and mass loss phenomena affecting evolved stars, and probing the environments of black holes in active galactic nuclei. As a first breakthrough, MATISSE will enlarge the spectral domain of current optical interferometers by offering the L and M bands in addition to the N band. This will open a wide wavelength domain, ranging from 2.8 to 13 μm, exploring angular scales as small as 3 mas (L band) / 10 mas (N band). As a second breakthrough, MATISSE will allow mid-infrared imaging - closure-phase aperture-synthesis imaging - with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. Moreover, MATISSE will offer a spectral resolution range from R ∼ 30 to R ∼ 5000. Here, we present one of the main science objectives, the study of protoplanetary disks, that has driven the instrument design and motivated several VLTI upgrades (GRA4MAT and NAOMI). We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performances. We also discuss the current status of the MATISSE instrument, which is entering its testing phase, and the foreseen schedule for the next two years that will lead to the first light at Paranal.
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?
MATISSE is the mid-infrared spectrograph and imager for the Very Large Telescope Interferometer (VLTI) at Paranal. This second generation interferometry instrument will open new avenues in the exploration of our Universe. Mid-infrared interferometry with MATISSE will allow significant advances in various fundamental research fields: studies of disks around young stellar objects where planets form and evolve, surface structures and mass loss of stars in late evolutionary stages, and the environments of black holes in active galactic nuclei. MATISSE is a unique instrument. As a first breakthrough it will enlarge the spectral domain used by optical interferometry by offering the L & M bands in addition to the N band, opening a wide wavelength domain, ranging from 2.8 to 13 μm on angular scales of 3 mas (L/M band) / 10 mas (N band). As a second breakthrough, it will allow mid-infrared imaging – closure-phase aperture-synthesis imaging – with up to four Unit Telescopes (UT) or Auxiliary Telescopes (AT) of the VLTI. MATISSE will offer various ranges of spectral resolution between R~30 to ~5000. In this article, we present some of the main science objectives that have driven the instrument design. We introduce the physical concept of MATISSE including a description of the signal on the detectors and an evaluation of the expected performance and discuss the project status. The operations concept will be detailed in a more specific future article, illustrating the observing templates operating the instrument, the data reduction and analysis, and the image reconstruction software.
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.
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.
The MUSE (Multi Unit Spectroscopic Explorer) instrument (see Bacon et al., this conference) for ESO's Very Large
Telescope VLT employs 24 integral field units (spectrographs). Each of these is equipped with its own cryogenically
cooled CCD head. The heads are individually cooled by continuous flow cryostats. The detectors used are deep depletion
e2v CCD231-84 with 4096x4112 active 15 μm pixels. The MUSE Instrument Detector System is now in the final
integration and test phase on the instrument.
This paper gives an overview of the architecture and performance of the complex detector system including ESO's New
General detector Controllers (NGC) for the 24 science detectors, the detector head electronics and the data acquisition
system with Linux Local Control Units. NGC is sub-divided into 4 Detector Front End units each operating 6 CCDs. All
CCDs are simultaneously read out through 4 ports to achieve short readout times at low noise levels.
All science grade CCDs were thoroughly characterized on ESO's optical detectors testbench facility and the test results
processed and documented in a semi-automated, reproducible way. We present the test methodology and the results that
fully confirm the feasibility of these detectors for their use in this challenging instrument.
MATISSE is a mid-infrared spectro-interferometer combining the beams of up to four Unit Telescopes or Auxiliary
Telescopes of the Very Large Telescope Interferometer (VLTI) of the European Southern Observatory.
MATISSE will constitute an evolution of the two-beam interferometric instrument MIDI. New characteristics present in
MATISSE will give access to the mapping and the distribution of the material, the gas and essentially the dust, in the
circumstellar environments by using the mid-infrared band coverage extended to L, M and N spectral bands. The four
beam combination of MATISSE provides an efficient uv-coverage: 6 visibility points are measured in one set and 4
closure phase relations which can provide aperture synthesis images in the mid-infrared spectral regime.
We give an overview of the instrument including the expected performances and a view of the Science Case. We present
how the instrument would be operated. The project involves the collaborations of several agencies and institutes: the
Observatoire de la Côte d’Azur of Nice and the INSU-CNRS in Paris, the Max Planck Institut für Astronomie of
Heidelberg; the University of Leiden and the NOVA-ASTRON Institute of Dwingeloo, the Max Planck Institut für
Radioastronomie of Bonn, the Institut für Theoretische Physik und Astrophysik of Kiel, the Vienna University and the
Konkoly Observatory.
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.
MUSE (Multi Unit Spectroscopic Explorer) is a second generation instrument developed for ESO (European Southern Observatory) and will be assembled to the VLT (Very Large Telescope) in 2012. The MUSE instrument can simultaneously record 90.000 spectra in the visible wavelength range (465-930nm), across a 1*1arcmin2 field of view, thanks to 24 identical Integral Field Units (IFU). A collaboration of 7 institutes has successfully passed the Final Design Review and is currently working on the first sub-assemblies. The sharing of performances has been based on 5 main functional sub-systems. The Fore Optics sub-system derotates and anamorphoses the VLT Nasmyth focal plane image, the Splitting and Relay Optics associated with the Main Structure are feeding each IFU with 1/24th of the field of view.
Each IFU is composed of a 3D function insured by an image slicer system and a spectrograph, and a detection function
by a 4k*4k CCD cooled down to 163°K. The 5th function is the calibration and data reduction of the instrument. This
article depicts the breakdown of performances between these sub-systems (throughput, image quality...), and underlines
the constraining parameters of the interfaces either internal or with the VLT. The validation of all these requirements is a
critical task started a few months ago which requires a clear traceability and performances analysis.
The Multi-Unit Spectroscopic Explorer (MUSE) is an integral-field spectrograph for the ESO Very Large Telescope.
After completion of the Final Design Review in 2009, MUSE is now in its manufacture and assembly phase. To achieve
a relative large field-of-view with fine spatial sampling, MUSE features 24 identical spectrograph-detector units. The
acceptance tests of the detector sub-systems, the design and manufacture of the calibration unit and the development of
the Data Reduction Software for MUSE are under the responsibility of the AIP. The optical design of the spectrograph
implies strict tolerances on the alignment of the detector systems to minimize aberrations. As part of the acceptance
testing, all 24 detector systems, developed by ESO, are mounted to a MUSE reference spectrograph, which is illuminated
by a set of precision pinholes. Thus the best focus is determined and the image quality of the spectrograph-detector
subsystem across wavelength and field angle is measured.
MUSE (Multi Unit Spectroscopic Explorer) is a second generation VLT panoramic integral field spectrograph
developed for the European Southern Observatory (ESO), operating in the visible wavelength range (0.465-0.93 μm). It
is composed of 24 identical Integral Field Units (IFU); each one incorporates an advanced image slicer associated with a
classical spectrograph and a detector vessel. The Image Slicer subsystem -ISS- is composed of two mirror arrays of 48
spherical elements each. It is made of Zerodur and uses an innovative polishing approach where all individual
components are polished together by classical method. The MUSE Spectrograph -SPS-, with fast output focal ratio of
f/1.95, implements a Volume Phase Holographic Grating - VPHG. The last subsystem, the Detector Vessel -DV- includes
a chip of 4k by 4k 15μm pixels supported by a Vacuum and Cryogenic System - VCS - provided by ESO.
The first out of 24 IFUs for MUSE instrument has been manufactured, aligned and tested last months. First, this paper
describes the optical design, the manufacturing and test results (image quality, pupil and field of view positioning) of
each subsystem independently. Second, we will focus on overall system performance (image quality and positioning) of
the spectrograph associated with the detector vessel. At the end, the test results (image quality, positioning, throughput,
mechanical interfaces) of the first IFU for MUSE instrument will be reported.
Most of them are compliant with requirements that it demonstrates that the manufacturing, integration, alignment and
tests processes are mature and gives good confidence for serial production by 24 times applied to MUSE instrument.
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.
We present results from the first two years of operations of the HARPS spectrograph installed on the ESO 3.6m
telescope at La Silla Observatory, Chile. This instrument, primarily built to detect extrasolar planetary systems, was
designed to achieve the highest radial velocity precision ever, thanks to high mechanical and environmental stability,
stable illumination, accurate wavelength calibration and tracking of instrumental drifts. HARPS has demonstrated a long-term
accuracy at the 1 m s-1 level and below, exploring a new regime in RV precision. We present recent improvements
in the wavelength calibration process, including the creation of a new ThAr reference atlas and the use of a much larger
number of lines to fit the wavelength solution. We have also investigated the intrinsic stability of ThAr calibration lamps
and show that they are able to provide a long-term wavelength reference at or below the 1 m s-1 level. Other instrumental
error sources such as guiding accuracy and photon noise are discussed and a global error budget is presented. These
efforts to further improve the RV precision are also part of a broader study to build a ultra-high accuracy spectrovelocimeter
for the ESO OWL telescope, the CODEX project. The aim of this instrument is to reach an accuracy of 1 cm
s-1 over timescales of at least ten years. This requires to push down the limits of present-day calibration techniques and to
explore new technologies able to provide ultra-precise Doppler measurements.
HARPS is a new high resolution fibre-fed spectrograph dedicated to the
extremely precise measurement of stellar radial velocities. After being used for about one year including the commissioning runs we report a very successful implementation of the measures taken to maximise stability, efficiency and spectral performance. Using the Simultaneous ThAr Reference Method a short term precision of 0.2 m/s during one night and a long term precision of the order of 1 m/s have been achieved. Equipped with a fully automated data reduction pipeline that produces solar system barycentric radial velocities in near real-time, HARPS promises to deliver data of unequalled quality. HARPS will primarily be used for the search for exoplanets and in the field of asteroseismology. First exciting scientific results confirm these expectations.
The high-resolution spectrograph HARPS (High-Accuracy Radial-velocity
Planet Searcher) will be installed on the 3.6m telescope at the ESO La Silla Observatory towards the end of 2002 and offered to the astronomical community by mid-2003. Assembly and integration of the instrument took place at the Geneva Observatory, Switzerland, during Spring 2002. At present, the verification of the system performance is in progress and is already in an advanced phase. We present in this paper the first results of our laboratory tests and describe various performance figures. We stress the outstanding mechanical and thermal stability of the instrument which are crucial for accurate radial velocity measurements. We also give a description of the simultaneous ThAr-reference technique which ensures an overall efficiency 6 times higher than with an the iodine cell absorption
method.
The combination of the high instrumental stability with the simultaneous ThAr-reference technique provides HARPS with characteristics highly adapted for accurate radial-velocity determination at the level of 1 ms-1. These make our instrument suitable for the detection of planetary systems and of extra-solar planets with sub-saturnian mass.
Superb quality small Volume Phase Holographic Gratings are available and in operation at ESO. Compared to Surface Relief Transmission Gratings, they have better efficiencies at high dispersion. Their role at ESO would/will expand with larger sizes, high index modulation (larger bandwidth; access to the near-IR domain), cooled operation (also for the near-IR) and the articulated spectrograph approach (higher dispersion & efficiency than with Grisms).
FORS is an all dioptric focal reducer designed for direct imaging, low-dispersion multi-object spectroscopy, imaging polarimetry and spectropolarimetry of faint objects. Two almost identical copies of the instrument were built by a consortium of three astronomical institutes under contract and in cooperation with ESO. FORS1 was installed in September 1998 and FORS2 in October 1999 at the Cassegrain foci of the ESO VLT unit telescope nos. 1 and 2. FORS1 is in regular operation since April 1999. Regular observation with FORS2 are scheduled to begin in April 2000.
We used FORS2 at UT2 of the VLT to obtain low resolution spectra of early type emission line stars in the field of the young open SMC cluster NGC 330. This cluster is known for its exceptional large number fraction of Be stars and could play a key role in constraining the Be phenomenon in general. 48 of the 59 program stars identified as H(alpha) excess sources by CCD imaging photometry can be confirmed to show H(alpha) line emission superimposed on a strong continuum. Comparison with VLT-FORS1 spectra collected a year earlier shows no or only a low significance of variability on the time scale of a year. To test the prediction of the hybrid model for global disk oscillations in Be star circumstellar disks we compared the number ratio of Be stars with asymmetric line profiles to the total number of Be stars with the known ratio of galactic field Be stars. About 10 of 47 emission line stars show asymmetric line profiles hence the theoretical prediction is not matched. We discuss several possibilities which might explain the discrepancy.
FORS1 (FOcal Reducer/low-dispersion Spectrograph) is an all dioptric focal reducer designed for direct imaging, low- dispersion multi-object spectroscopy, imaging polarimetry and spectro-polarimetry of faint objects. Two identical copies of the instrument (FORS 1 and 2) are being built by a consortium of three astronomical institutes (Landessternwarte Heidelberg and the University Observatories of Gottingen and Munich) under contract and in cooperation with ESO. FORS 1 and 2 will be installed, respectively, in 1998 and 2000 at the Cassegrain foci of the ESO VLT unit telescopes nos. 1 and 2. For the tests of FORS in Europe, a telescope and star simulator was built, which allows to incline and rotate the whole instrument and to simulate stars in the field of view at various seeing conditions. FORS 1 was integrated at the telescope simulator and saw its 'first light' in the integration facility in November 1996. Since then the electro-mechanical functions, the image motion due to flexure, the calibration units, the optical performance and the instrument software were tested and optimized. This paper presents a summary of the procedure and the results of the tests.
The need for atmospheric dispersion correction on large telescopes is well known. Therefore it was decided to implement atmospheric dispersion correctors for FORS, the focal reducer/spectrographs of the ESO very large telescope. The boundary conditions at the VLT Cassegrain foci excluded however all previously known ADC concepts and therefore we were forced to design a new one, the longitudinal atmospheric dispersion corrector (LADC) consisting of two thin prisms with variable distance. This design has several advantages compared to the 'classical concepts:' among others it avoids tilting the pupil axis and uses only one material (silica) which has a very high transmission over the operating wavelength range of FORS (330 - 1000 nm).
The hardware construction of FORS1, the first of the two focal reducer/low dispersion spectrographs of the ESO very large telescope (VLT), is now finished. An extensive testing program is under way which will guarantee that the instrument is fully understood and well calibrated when it will be installed at the Cassegrain focus of the first unit telescope of the VLT in 1998. This program includes a full characterization of the optical system and the evaluation of the setting accuracies and reproducibility of the numerous electromechanical functions as well as testing the flexure compensation which will minimize image shift during telescope motions. Telescope and star simulators were specially built for this purpose in order to test the optical and mechanical behavior of the instrument on the 8 m-telescope. Acceptance tests of the optical performance and the subsystem tests of all electromechanical functions indicate an excellent quality, especially for the complex multi object spectroscopy unit, while the overall system tests are just starting.
The focal reducer and low dispersion spectrograph FORS which is presently under construction for the ESO Very Large Telescope (VLT) will be an all dioptric focal reducer instrument designed for direct imaging, low-dispersion multi object spectroscopy, imaging and spectropolarimetry of faint objects. A central mechanical component of FORS is the multi object spectroscopy (MOS) unit. The design and the observation capabilities of the MOS are described. Further details on the whole instrument are given in [1]. Two identical copies of the instrument will be built by a consortium of three astronomical institutes (Landessterwarte Heidelberg and the Unviersity Observatories of Gottingen and Munich) under contract and in cooeration with ESO. The instruments will be installed at the Cassegrain foci of two unit telescopes of the VLT.
The design and the expected performance of the FOcal Reducer/low- dispersion Spectrograph (FORS) for the Very Large Telescope (VLT) of the European Southern Observatory (ESO) are described. FORS is an all dioptric focal reducer designed for direct imaging, low- dispersion multi-object spectroscopy (MOS), imaging polarimetry and spectro-polarimetry of faint objects in the spectral range from 330 nm to 1.1 (mu) $m. The field of view is 6.83 X 6.83 arcmin2 with an image scale of 0.2 arcsec/pixel. To take full advantage of excellent seeing, a configuration with an image scale of 0.1 arcsec/pixel can be selected. In the MOS mode, simultaneous spectroscopy of up to 19 objects is possible. Two copies of the instrument (denoted `FORS I' and `FORS II', respectively) are under construction and will be installed at the Cassegrain foci of the VLT unit telescope Nos. 1 and 3.
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