MOONS is the Multi-Object Optical and Near-infrared Spectrograph for the ESO Very Large Telescope (VLT). MOONS will be able to simultaneously observe ~1000 targets using individual robotic theta-phi positioners. The instrument will provide both medium and high-resolution spectral coverage across the wavelength range of 0.65 μm to 1.8 μm. In this paper we will describe the integration and testing of the fully-assembled Rotating Front End of MOONS. This incorporates the fibre positioning module, the front-end structure and the metrology, calibration and acquisition sub-systems. There will also be a discussion of system control and associated hazard analyses and safety cases. The as-built performance of the completed system will be demonstrated, including metrology-verified fibre positioning accuracy, reconfiguration efficiency, and flat-field fibre calibration performance. Finally, a summary of the successful installation of the field corrector assembly at VLT UT1 will be presented.
MOSAIC is the Multi-Object Spectrograph (MOS) for the 39m Extremely Large Telescope (ELT) of the European Southern Observatory (ESO), with unique capabilities in terms of multiplex, wavelength coverage and spectral resolution. It is a versatile multi-object spectrograph working in both the Visible and NIR domains, designed to cover the largest possible area (∼40 arcmin2) on the focal plane, and optimized to achieve the best possible signal-to-noise ratio on the faintest sources, from stars in our Galaxy to galaxies at the epoch of the reionization. In this paper we describe the main characteristics of the instrument, including its expected performance in the different observing modes. The status of the project will be briefly presented, together with the positioning of the instrument in the landscape of the ELT instrumentation. We also review the main expected scientific contributions of MOSAIC, focusing on the synergies between this instrument and other major ground-based and space facilities.
MOONS (Multi-Object Optical and near-Infrared Spectrograph) will be a fibre-fed, optical to near-infrared multi-object spectrograph designed to utilise the full 25 arcminute diameter field-of-view of the Very Large Telescope and provide a multiplex capability of over 1000 fibres. The baseline design includes a single focal plate and fibre positioning subsystem, consisting of 1000 small dual radial arm modules, which are used to place each fibre, in the exact x, y and z position in the telescope focal plane. Each fibre has a microlens to focus the beam into the fibre at a relatively fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD). The light is then fed through the fibres to two identical, cryogenic triple arm spectrographs, mounted on the instrument platform. In each spectrograph, the light from 512 fibres, arranged in a pseudo-slit, is split by dichroic filters into three channels (RI, YJ and H) and dispersed on to 4k x 4k detectors in each channel. At the slit there are 32 slitlets, each containing 16 fibres, which feed the collimator. They have been co-aligned to minimise the tilt.
The Multi Object Optical and Near-infrared Spectrograph (MOONS) instrument is the next generation multi-object spectrograph for the Very Large Telescope (VLT). The instrument combines the high multiplexing capability offered by 1000 optical fibres deployed by individual robotic positioners with a novel spectrograph able to provide both low- and high-resolution spectroscopy simultaneously across the wavelength range 0.64μm - 1.8μm. Powered by the collecting area of the 8-m VLT, MOONS will provide the astronomical community with a world-leading facility able to serve a wide range of Galactic, Extragalactic and Cosmological studies. This paper provides an updated overview of the instrument and its construction progress, reporting on the ongoing integration phase.
MOONS will be the next Multi-Object Optical and Near-infrared Spectrograph for the Very Large Telescope, able to simultaneously observe 1000 targets, feeding a set of optical fibres which can be placed at user-specified locations on the Nasmyth focal plane using individual robotic positioners. The sub-fields thus selected are then driven by the fibres into two identical cryogenic spectrographs mounted on the Nasmyth platform of one of the ESO VLT 8 m telescopes. The instrument will provide both medium and high-resolution spectral coverage across the wavelength range of 0.65 μm to 1.8 μm. In this paper we will describe the manufacturing, integration and tests of the two components that interface with the telescope: the MOONS Field Corrector (FC) and the Rotating Front End (RFE) Assemblies. The FC optics will correct the off-axis aberrations of the telescope, as well as determining the shape of the focal surface and the pupil location. The RFE assembly consists of a rotating part, which will be mounted on the VLT Nasmyth Rotator, and be connected to the two static Spectrographs via fibre assemblies, and all the sub-assemblies that give support to the fibre positioning, metrology and calibration units.
MOSAIC is the Multi-Object Spectrograph for the ESO Extremely Large Telescope, approved to enter Phase B beginning 2022. It is conceived as a multi- purpose instrument covering the Visible and Near Infrared bandwidth (0.45 –1.8 μm) with two observing modes: spatially resolved spectroscopy with 8 integral field units; and the simultaneous observation of 200 objects in the VIS and NIR in unresolved spectroscopy.
We present an overview of the main MOSAIC science drivers and the actual baseline design for the instrument. The prototyping and developments undertaken by the consortium to evaluate the feasibility of the project are also discussed.
The Multi Object Optical and Near-infrared Spectrograph (MOONS) instrument is the next generation multi-object spectrograph for the VLT. This powerful instrument will combine for the first time: the large collecting power of the VLT with a high multipexing capability offered by 1000 optical fibres moved with individual robotic positioners and a novel, very fast spectrograph able to provide both low- and high-resolution spectroscopy simultaneously across the wavelength range 0.64μm - 1.8μm. Such a facility will provide the astronomical community with a powerful, world-leading instrument able to serve a wide range of Galactic, Extragalactic and Cosmological studies. Th final assembly, integration and verification phase of the instrument is now about to start performance testing.
MOONS (Multi-Object Optical and near-Infrared Spectrograph) will be a fibre-fed, optical to near-infrared multi-objet spectrograph designed to utilise the full 25 arcminute diameter field-of-view of the Very Large Telescope and with a multiplex capability of over 1000 fibres. The baseline design includes a single focal plate and fibre positioning subsystem, consisting of up 1024 small dual radial arm modules, which are used to place each fibre, in the exact x, y and z position in the telescope focal plane. Each fibre has a microlens to focus the beam into the fibre at a relatively fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD). The light is then fed through the fibres to two identical, cryogenic triple arm spectrographs, mounted on the instrument platform. In each spectrograph, the light from 512 fibres, arranged in a pseudo-slit, is split by dichroic filters into three channels (RI, YJ and H) and dispersed on to 4k x 4k detectors in each channel.
The Multi-Object Optical and near-Infrared Spectrograph (MOONS) will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.64μm-1.8μm, with a multiplex capability of over 1000 fibres. Each spectrograph will produce spectra for 500 targets simultaneously, each with its own dedicated sky fibre for optimal sky subtraction. The system will have both a medium resolution (R~4000-6000) mode and a high resolution (R~20000) mode. The fibres are used to pick off each sub field of 1” and are used to transport the light from the instrument focal plane to the two spectrographs. Each fibre has a microlens to focus the beam into the fibre at a relative fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD). This paper describes the final characteristics and performances of the MOONS fibre link, and their installation status into the slit of the spectrograph during the integration phase in Europe.
MOONS will be the next Multi-Object Optical and Near-infrared Spectrograph for the Very Large Telescope, able to simultaneously observe 1000 targets, feeding a set of optical fibres which can be placed at user-specified locations on the Nasmyth focal plane using individual robotic positioners. The sub-fields thus selected are then driven by the fibres into two identical cryogenic spectrographs mounted on the Nasmyth platform of one of the ESO VLT 8 m telescopes. The instrument will provide both medium and high-resolution spectral coverage across the wavelength range of 0.65 μm to 1.8 μm. In this paper we will describe the two components that interface with the telescope: the MOONS Field Corrector (FC) and the Rotating Front End (RFE) Assemblies. The FC optics will correct the off-axis aberrations of the telescope, as well as determining the shape of the focal surface and the pupil location. The RFE assembly consists of a rotating part, which will be mounted on the VLT Nasmyth Rotator, and be connected to the two static Spectrographs via fibre assemblies, and all the sub-systems that give support to the fibre positioning, metrology and calibration units.
The performance of astrophotonic instruments is determined by various factors including the quality of optical surfaces and the precise alignment of components. As instruments become more complex and compact, the manufacture and assembly of components is increasingly challenging. We propose that a laser-based glass microfabrication technique known as ultrafast-laser assisted etching (ULAE) is ideally suited to the manufacture of both existing and novel components for astrophotonic instruments. To demonstrate this potential, we will present ULAE manufactured microlenses with integrated passive alignment features for efficient optical fiber coupling. A full physical and optical characterization of the micro-lenses is given. These components have applications in fiber-fed multi-object spectrographs.
After completion of its final-design review last year, it is full steam ahead for the construction of the MOONS instrument - the next generation multi-object spectrograph for the VLT. This remarkable instrument will combine for the first time: the 8 m collecting power of the VLT, 1000 optical fibres with individual robotic positioners and both medium- and high-resolution spectral coverage acreoss the wavelength range 0.65μm - 1.8 μm. Such a facility will allow a veritable host of Galactic, Extragalactic and Cosmological questions to be addressed. In this paper we will report on the current status of the instrument, details of the early testing of key components and the major milestones towards its delivery to the telescope.
Following a successful Phase A study, we introduce the delivered conceptual design of the MOSAIC1 multi-object spectrograph for the ESO Extremely Large Telescope (ELT). MOSAIC will provide R~5000 spectroscopy over the full 460-1800 nm range, with three additional high-resolution bands (R~15000) targeting features of particular interest. MOSAIC will combine three operational modes, enabling integrated-light observations of up to 200 sources on the sky (high-multiplex mode) or spectroscopy of 10 spatially-extended fields via deployable integral-field units: MOAO6 assisted high-definition (HDM) and Visible IFUs (VIFU). We will summarise key features of the sub-systems of the design, e.g. the smart tiled focal-plane for target selection and the multi-object adaptive optics used to correct for atmospheric turbulence, and present the next steps toward the construction phase.
Product Assurance is an essential activity to support the design and construction of complex instruments developed for major scientific programs. The international size of current consortia in astrophysics, the ambitious and challenging developments, make the product assurance issues very important. The objective of this paper is to focus in particular on the application of Product Assurance Activities to a project such as MOSAIC, within an international consortium. The paper will also give a general overview on main product assurance tasks to be implemented during the development from the design study to the validation of the manufacturing, assembly, integration and test (MAIT) process and the delivery of the instrument.
When combined with the huge collecting area of the ELT, MOSAIC will be the most effective and flexible Multi-Object Spectrograph (MOS) facility in the world, having both a high multiplex and a multi-Integral Field Unit (Multi-IFU) capability. It will be the fastest way to spectroscopically follow-up the faintest sources, probing the reionisation epoch, as well as evaluating the evolution of the dwarf mass function over most of the age of the Universe. MOSAIC will be world-leading in generating an inventory of both the dark matter (from realistic rotation curves with MOAO fed NIR IFUs) and the cool to warm-hot gas phases in z=3.5 galactic haloes (with visible wavelenth IFUs). Galactic archaeology and the first massive black holes are additional targets for which MOSAIC will also be revolutionary. MOAO and accurate sky subtraction with fibres have now been demonstrated on sky, removing all low Technical Readiness Level (TRL) items from the instrument. A prompt implementation of MOSAIC is feasible, and indeed could increase the robustness and reduce risk on the ELT, since it does not require diffraction limited adaptive optics performance. Science programmes and survey strategies are currently being investigated by the Consortium, which is also hoping to welcome a few new partners in the next two years.
The Multi-Object Optical and Near-Infrared Spectrograph (MOONS) will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.64μm-1.8μm, with a multiplex capability of over 1000 fibres. This can be configured to produce spectra for chosen targets and have close proximity sky subtraction if required. The system will have both a medium resolution (R~4000-6000) mode and a high resolution (R~20000) mode. The fibre positioning units are used to position each fibre independently in order to pick off each sub field of 1.0” within a circular patrol area of ~85” on sky (50mm physical diameter). The nominal physical separation between FPUs is 25mm allowing a 100% overlap in coverage between adjacent units. The design of the fibre positioning units allows parallel and rapid reconfiguration between observations. The kinematic geometry is such that pupil alignment is maintained over the patrol area. This paper presents the design of the Fibre Positioning Units at the preliminary design review and the results of verification testing of the advanced prototypes.
We present the Final Design of the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT), together with a status update on the details of manufacturing, integration and the overall project schedule now that all the major fabrication contracts are in place. We also present a summary of the current planning behind the 5-year initial phase of survey operations. WEAVE will provide optical ground-based follow up of ground-based (LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object (MOS) fibres, 20 integral field units, or a single large IFU for each observation. The fibres are fed to a single (dual-beam) spectrograph, with total of 16k spectral pixels, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with limited coverage in each arm at R~20000. The project is now in the manufacturing and integration phase with first light expected for early of 2018.
The Multi-Object Optical and Near-infrared Spectrograph (MOONS) will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.64μm-1.8μm, with a multiplex capability of over 1000 fibres. Each spectrograph will produce spectra for 500 targets simultaneously, each with its own dedicated sky fibre for optimal sky subtraction. The system will have both a medium resolution (R~4000-6000) mode and a high resolution (R~20000) mode.
The fibres are used to pick off each sub field of 1" and are used to transport the light from the instrument focal plane to the two spectrographs. Each fibre has a microlens to focus the beam into the fibre at a relative fast focal ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD).
KEYWORDS: Sensors, Point spread functions, Diffraction, Spectrographs, Computer simulations, Zemax, Device simulation, Signal to noise ratio, Near infrared, Photon counting
MOONS will be the next near infrared fiber fed multi-object spectrograph for the Very Large Telescope, that will offer a
one thousand multiplexing capability and a simultaneous coverage of the wavelength range from 0.8 to 1.8 μm.
With the aim of quantitatively i) assessing the instrument performances with respect to sensitivity and OH subtraction, ii)
blind-testing the 1D spectra extraction and calibration, provided by the data reduction pipeline, and iii) testing the
technical solutions adopted for reaching the outstanding instrument requirements, we have developed “Virtual
MOONS”, an end-to-end software simulator, which quantitatively computes high fidelity focal plane raw images,
emulating the output of the detector electronics.
Starting from an ideal photon image derived from the geometrical optics propagation and Point Spread Function (PSF)
variations computed by the ZEMAX optical design, the end-to-end optical budget is introduced along with the stray light
contributions, resulting in the expected photon counts impinging the detector pixels. Then the photon image plus photon
noise is converted to digital counts by means of a detailed detector simulation, including pixel-to-pixel response
variation, dark, bias, read-out noise, cosmetics, charge diffusion, flatness and read-out schemes. Critical points like fiber
differential response, PSF haloes and sky emission variations have been also taken into account.
The current status of this work is presented with an example simulated image and numerical results.
This paper presents the latest optical design for the MOONS triple-arm spectrographs. MOONS will be a Multi-Object
Optical and Near-infrared Spectrograph and will be installed on one of the European Southern Observatory (ESO) Very
Large Telescopes (VLT). Included in this paper is a trade-off analysis of different types of collimators, cameras,
dichroics and filters.
WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in La
Palma, Canary Islands, Spain. WEAVE mainly aims at spectroscopic follow-up of ground-based (e.g. LOFAR) and
space-based (GAIA) surveys. The facility consists of a new 2-degree field-of-view prime focus corrector with a 1000-
multiplex fibre positioner, a small number of individually deployable integral field units, and a large single integral field
unit. The IFUs (Integral Field Units) and the MOS fibres can be used to feed a dual-beam spectrograph that will provide
full coverage of the majority of the visible spectrum in a single exposure at a spectral resolution of ~5000 or modest
wavelength coverage in both arms at a resolution ~20000. The instrument is expected to be on-sky by 2017 to provide
spectroscopic sampling of the fainter end of the Gaia astrometric catalogue, chemical labeling of stars to V~17, and
dedicated follow up of substantial numbers of sources from the medium deep LOFAR surveys.
After a brief description of the MOS fibre bundle, we described the proposed test plan and the test bench of the 2x1000
WEAVE MOS fibres. The test bench allows us to evaluate the Focal Ratio Degradation and the throughput of the fibers
fitted with their buttons and slitlets.
MOONS will exploit the full 500 square arcmin field of view offered by the Nasmyth focus of the Very Large Telescope
and will be equipped with two identical triple arm cryogenic spectrographs covering the wavelength range 0.8 - 1.8 μm,
with a multiplex capability of approximately 1000 fibres. Each triple arm spectrograph will produce spectra for half of
the targets simultaneously. The system will have both a medium resolution (R~4000-6000) mode and a high resolution
(R~20000) mode.
The fibres are used to pick off each sub field of 1.05 arcseconds and are used to transport the light from the instrument
focal plane to the two spectrographs. Each fibre has a microlens to focus the beam into the fibre at a relative fast focal
ratio of F/3.65 to reduce the Focal Ratio Degradation (FRD).
This paper presents the overall design of the fibre system and describes the specific developments required to optimise
its performance. The design of the fibre input optics, the choice of the fibre connector, and the layout of the slit end are
described. The results of preliminary tests to measure the effect of twisting on the FRD performance of prototype fibres
are also discussed.
MOONS is a new Multi-Object Optical and Near-infrared Spectrograph selected by ESO as a third generation
instrument for the Very Large Telescope (VLT). The grasp of the large collecting area offered by the VLT (8.2m
diameter), combined with the large multiplex and wavelength coverage (optical to near-IR: 0.8μm - 1.8μm) of MOONS
will provide the European astronomical community with a powerful, unique instrument able to pioneer a wide range of
Galactic, Extragalactic and Cosmological studies and provide crucial follow-up for major facilities such as Gaia,
VISTA, Euclid and LSST. MOONS has the observational power needed to unveil galaxy formation and evolution over
the entire history of the Universe, from stars in our Milky Way, through the redshift desert, and up to the epoch of very
first galaxies and re-ionization of the Universe at redshift z>8-9, just few million years after the Big Bang. On a
timescale of 5 years of observations, MOONS will provide high quality spectra for >3M stars in our Galaxy and the
local group, and for 1-2M galaxies at z>1 (SDSS-like survey), promising to revolutionise our understanding of the
Universe.
The baseline design consists of ~1000 fibers deployable over a field of view of ~500 square arcmin, the largest patrol
field offered by the Nasmyth focus at the VLT. The total wavelength coverage is 0.8μm-1.8μm and two resolution
modes: medium resolution and high resolution. In the medium resolution mode (R~4,000-6,000) the entire wavelength
range 0.8μm-1.8μm is observed simultaneously, while the high resolution mode covers simultaneously three selected
spectral regions: one around the CaII triplet (at R~8,000) to measure radial velocities, and two regions at R~20,000 one
in the J-band and one in the H-band, for detailed measurements of chemical abundances.
We present an overview of and status report on the WEAVE next-generation spectroscopy facility for the William
Herschel Telescope (WHT). WEAVE principally targets optical ground-based follow up of upcoming ground-based
(LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree
prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object
(MOS) fibres, 20 integral field units, or a single large IFU for each observation. The fibres are fed to a single
spectrograph, with a pair of 8k(spectral) x 6k (spatial) pixel cameras, located within the WHT GHRIL enclosure on the
telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single
exposure, or a high resolution mode with limited coverage in each arm at R~20000. The project is now in the final
design and early procurement phase, with commissioning at the telescope expected in 2017.
We present the preliminary design of the WEAVE next generation spectroscopy facility for the William Herschel
Telescope (WHT), principally targeting optical ground-based follow up of upcoming ground-based (LOFAR) and spacebased
(Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2 degree prime focus field of view
at the WHT, with a buffered pick and place positioner system hosting 1000 multi-object (MOS) fibres or up to 30
integral field units for each observation. The fibres are fed to a single spectrograph, with a pair of 8k(spectral) x 6k
(spatial) pixel cameras, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting
observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with
limited coverage in each arm at R~20000.
The EAGLE and EVE Phase A studies for instruments for the European Extremely Large Telescope (E-ELT) originated
from related top-level scientific questions, but employed different (yet complementary) methods to deliver the required
observations. We re-examine the motivations for a multi-object spectrograph (MOS) on the E-ELT and present a unified
set of requirements for a versatile instrument. Such a MOS would exploit the excellent spatial resolution in the near-infrared envisaged for EAGLE, combined with aspects of the spectral coverage and large multiplex of EVE. We briefly
discuss the top-level systems which could satisfy these requirements in a single instrument at one of the Nasmyth foci of
the E-ELT.
MOONS is a new conceptual design for a Multi-Object Optical and Near-infrared Spectrograph for the Very Large
Telescope (VLT), selected by ESO for a Phase A study. The baseline design consists of ~1000 fibers deployable over a
field of view of ~500 square arcmin, the largest patrol field offered by the Nasmyth focus at the VLT. The total
wavelength coverage is 0.8μm-1.8μm and two resolution modes: medium resolution and high resolution. In the medium
resolution mode (R~4,000-6,000) the entire wavelength range 0.8μm-1.8μm is observed simultaneously, while the high
resolution mode covers simultaneously three selected spectral regions: one around the CaII triplet (at R~8,000) to
measure radial velocities, and two regions at R~20,000 one in the J-band and one in the H-band, for detailed
measurements of chemical abundances.
The grasp of the 8.2m Very Large Telescope (VLT) combined with the large multiplex and wavelength coverage of
MOONS – extending into the near-IR – will provide the observational power necessary to study galaxy formation and
evolution over the entire history of the Universe, from our Milky Way, through the redshift desert and up to the epoch
of re-ionization at z<8-9. At the same time, the high spectral resolution mode will allow astronomers to study chemical
abundances of stars in our Galaxy, in particular in the highly obscured regions of the Bulge, and provide the necessary
follow-up of the Gaia mission. Such characteristics and versatility make MOONS the long-awaited workhorse near-IR
MOS for the VLT, which will perfectly complement optical spectroscopy performed by FLAMES and VIMOS.
WEAVE is a new wide-field spectroscopy facility proposed for the prime focus of the 4.2m William Herschel telescope.
The facility comprises a new 2 degree field of view prime focus corrector with a 1000-multiplex fibre positioner, a small
number of individually deployable IFUs, and a large single IFU. The IFUs and the MOS fibres can be used to feed a
dual-beam spectrograph that will provide full coverage of the majority of the visible spectrum in a single exposure at a
resolution ~5000 or two 50nm-wide regions at a resolution of ~20000.
This paper sums up the design of these two modes and describes the specific developments required to optimise the
performances of the fibre system.
We present preliminary results on on-sky test of sky subtraction methods for fiber-fed spectrograph. Using
dedicated observation with FLAMES/VLT in I-band, we have tested the accuracy of the sky subtraction for 4
sky subtraction methods: mean sky, closest sky, dual stare and cross-beam switching. The cross beam-switching
and dual stare method reach accuracy and precision of the sky subtraction under 1%. In contrast to the commonly
held view in the literature, this result points out that fiber-fed spectrographs are adapted for the observations
of faint targets.
The OPTIMOS-EVE concept provides optical to near-infrared (370-1700 nm) spectroscopy, with three spectral
resolution (5000, 15000 and 30000), with high simultaneous multiplex (at least 200). The optical fibre links are
distributed in four kinds of bundles: several hundreds of mono-object systems with three types of bundles, fibre size
being used to adapt spectral resolution and 30 deployable medium IFUs (about 2"x3"). We are optimising the design of
deployable IFUs to warrant sky subtraction for the faintest extragalactic sources.
This paper gives the design and results of the prototype for the high resolution mode and the preliminary design of a
medium IFU developed in collaboration between the GEPI and the LNA.
OPTIMOS-EVE (OPTical Infrared Multi Object Spectrograph - Extreme Visual Explorer) is the fiber fed multi object
spectrograph proposed for the E-ELT. It is designed to provide a spectral resolution ranging from 5000 to 30.000, at
wavelengths from 0.37 μm to 1.70 μm, combined with a high multiplex (>200) and a large spectral coverage. The
system consists of three main modules: a fiber positioning system, fibers and a spectrograph.
The OPTIMOS-EVE Phase-A study, carried out within the framework of the ESO E-ELT instrumentation studies, has
been performed by an international consortium consisting of institutes from France, Netherlands, United Kingdom, Italy
and Denmark.
This paper describes the design tradeoff study and the key issues determining the price and performance of the
instrument.
The OPTIMOS-EVE concept provides optical to near-infrared (370-1700 nm) spectroscopy, with three spectral
resolution (5000, 15000 and 30000), with high simultaneous multiplex (at least 200). The optical fibre links are
distributed in five kinds of bundles: several hundreds of mono-object systems with three types of bundles, fibre size
being used to adapt slit with, and thus spectral resolution, 30 deployable medium IFUs (about 2"×3") and one large IFU
(about 6"×12").
This paper gives an overview of the design of each mode and describes the specific developments required to optimise
the performances of the fibre system.
ESA's cornerstone mission Gaia will construct a billion-star catalogue down to magnitude 20 but will only provide
detailed chemical information for the brighter stars and will be lacking radial velocity at the faint end due to
insufficient Signal-to-Noise Ratios (SNR). This calls for the deployment of a ground spectrograph under time
scales coherent with those of Gaia for a complementary survey.
The GYES instrument is a high resolution (~ 20,000) spectrometer proposed for installation on the Canada-
France-Hawaii Telescope (CFHT) to perform this survey in the northern hemisphere. It exploits the large Field
of View (FoV) available at the prime focus together with a high multiplex (~ 500 fibres) to achieve a SNR of 30
in two hours at magnitude 16 and render the survey possible on the order of 300 nights. The on-going feasibility
study aims at jointly optimising all components of the system: the field corrector, the positioner, the fibres
and the spectrograph. The key challenges consist in accommodating the components in the highly constrained
environment of the primary focus, as well as in achieving maximum efficiency thanks to high transmission
and minimum reconfiguration delays. Meanwhile, for GYES to have its first light at the time of Gaia's initial
data release (2014-2015), it is mandatory to keep its complexity down by designing a predominantly passive
instrument.
OPTIMOS-EVE (OPTical Infrared Multi Object Spectrograph - Extreme Visual Explorer) is the fibre fed multi object
spectrograph proposed for the European Extremely Large Telescope (E-ELT), planned to be operational in 2018 at Cerro
Armazones (Chile). It is designed to provide a spectral resolution of 6000, 18000 or 30000, at wavelengths from 370 nm
to 1.7 μm, combined with a high multiplex (>200) and a large spectral coverage. Additionally medium and large IFUs
are available. The system consists of three main modules: a fibre positioning system, fibres and a spectrograph.
The recently finished OPTIMOS-EVE Phase-A study, carried out within the framework of the ESO E-ELT
instrumentation studies, has been performed by an international consortium consisting of institutes from France,
Netherlands, United Kingdom and Italy. All three main science themes of the E-ELT are covered by this instrument:
Planets and Stars; Stars and Galaxies; Galaxies and Cosmology.
This paper gives an overview of the OPTIMOS-EVE project, describing the science cases, top level requirements, the
overall technical concept and the project management approach. It includes a description of the consortium, highlights of
the science drivers and resulting science requirements, an overview of the instrument design and telescope interfaces, the
operational concept, expected performance, work breakdown and management structure for the construction of the
instrument, cost and schedule.
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.
X-shooter is a new high-efficiency integral field spectrograph mainly dedicated to the spectroscopic follow up of the gamma ray bursts. X-shooter will operate at the Cassegrain focus of the VLT with an intermediate spectral resolution of ~5000, and will provide a very wide simultaneous spectral coverage, ranging from 320 to 2500 nm. The instrument consists in a central structure which supports three prism cross-dispersed echelle spectrographs respectively optimized for the UV-blue, Visible and Near-IR wavelength ranges.
X-shooter will offer an image slicer based Integral Field Unit (IFU) designed to analyse a 1.8"x4" input field into 3 slices of 0.6"x4"and to align then on a 12" long slit. The principle of the IFU is that the central slice does not include any dioptre, the light is directly transmitted to the spectrographs. Only the two lateral sliced fields are reflected toward the two pairs of spherical mirrors and re-aligned at both ends of the previous slice in order to form the exit slit. We present here the IFU design developed at the Observatoire de Paris.
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.
FALCON is an original concept for next generation instrumentation at ESO VLT or at future ELTs. It is a multi-objects integral field spectrograph with multiple integral field units (IFU) performing adaptive optics correction in order to reach spatial and spectral resolution ideally suited for distant galaxy studies. The resolutions required for the VLT are typically 0.15 - 0.25 arcsec and R>=5000 in the 0.8-1.8 μm wavelength range. The studied galaxies are very faint objects that cannot be directly used to perform wavefront sensing. Thus, we use at least three Wave-Front Sensors (WFS) per IFU to sense the wavefront of stars located around the galaxy, and the on-axis wavefront from the galaxy will be deduced from the off-axis measurements by atmospheric tomography, and then corrected thanks to an adaptive optics (AO) system within each IFU. Since the WFS is ideally located directly in the focal plane of the telescope, this implies to develop miniaturized devices for the wavefront sensing. Our approach is based on a Shack Hartmann principle and - instead of using a bulky detector behind - we plan to use a miniaturized system including fibers able to transport the light from the focal plane of the microlens array towards a place where the bulk issue is less critical. We draw up the main specifications of this miniaturized system and we present the characteristics of elements manufactured by using new microlithography techniques.
The FLAMES project is the VLT Fibre Facility. It includes the fibre positioner OzPoz linking the GIRAFFE and UVES spectrographs. FLAMES is located on the Nasmyth Platform A of the Kueyen VLT telescope. The optical fibre link is arranged in four bundles: the Medusa system with 132 single fibres for multi-object spectroscopy, 15 deployable IFU modules for integral field spectroscopy of small objects, the Argus large integral field unit with two possible samplings and a bundle of 8 fibres and 55 m long linking OzPoz to UVES, a high resolution spectrograph situated on the opposite Nasmyth platform.
This paper describes the final characteristics and performances of all the fibre bundles and the status at their installation at the telescope.
Our team is designing and realizing the fiber links from which two spectrographs will operate at the second unit of the Very Large Telescope. GIRAFFE is an intermediate resolution spectrograph which has access to the entire field of the Nasmyth focus and is equipped with three fiber links producing alternately 132 spectra at the same time, 15 tri- dimensional spectra or 300 spectra for a single object. The last fiber link is intended to provide simultaneously with GIRAFFE, the observation of 8 objects at a higher resolution with UVES. All these observation modes will be available at VLT by the end of 2001. The specific development of the fiber links includes the systematic use of simultaneous calibration. This paper sums up the design of each mode and describes the specific developments required to optimize the performances of the fiber system. A full description of GIRAFFE, of its fiber link and of the related scientific programs is available at http://giraobs.obspm.fr.
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