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The 4MOST1 instrument is a multi-object-spectrograph for the ESO-VISTA telescope. The 4MOST long fiber feed links the AESOP2 fiber positioner to two low-resolution spectrographs (1624 fibers) and one high-resolution spectrograph (812 fibers). In addition to the 2436 science fibers, the system includes guide fiber bundles, metrology fiducial fibers and simultaneous calibration fibers for the spectrographs. To validate the design approaches, including fiber connectors and cable rotator, pre-production fiber cables have been built and evaluated. This paper presents the near final design of the fiber feed subsystem and its performance results pertaining to throughput homogeneity, focal ratio degradation, and connector loss of the pre-production cables.

4MOST is a fibre-fed, multi-object spectroscopic survey facility to be installed on the VISTA telescope at ESO's Paranal observatory. This paper presents the final mechanical design of the optical fibre route from the fibre positioner at the focal plane of VISTA to the fibre-slits within the high- and low-resolution spectrographs below the azimuth platform. The technical challenges are to provide a safe, durable and efficient fibre route for over 2400 fibres. To accommodate the movements of the telescope, a Cassegrain Cable Wrap and a novel elevation chain concept has been prototyped and extensively tested to validate the design solutions.

In recent decades, spectroscopic capabilities have been significantly enhanced by new technological developments, in particular spatial reformatting. Spatial reformatting allows multiple functionalities: the observation of a larger area of sky, obtaining the spectra of all spatial elements under the same atmospheric conditions; modification of the shape and size of the field of view; focal-ratio conversion for the optimized coupling between the telescope and the spectrograph; increase in the spatial and spectral resolving power; the observation of multiple objects; homogeneity in the illumination; scrambling of spatial and/or phase induced structure with the instrument, thus improving the system stability; relocation of the exit pupil, especially important for telecentric systems. The impact of reformatting and the breadth of science cases is so great that many alternative methods and technologies have been proposed: image slicers using refractive or reflective solutions; optical fibers with different core sizes and geometries; microlenses used in isolation or combined with fibers and more recently, photonic devices such as Photonic lanterns to produce modal decomposition. In this paper, a comparison between all currently available options is presented, with a detailed analysis of their advantages and limitations and a proposal for a new reformatter combining slicers and photonic devices. This proposal presents the advantages of the other alternatives and additionally offers: minimization of focal-ratio degradation; produces image and modal decomposition; improves the throughput along the spectral range, increases the spectral resolving power and adds the functionality of scrambling. All of these advantages are combined in a system where photonic and astronomical instrumentation capabilities are joined in an innovative solution with many applications, like for example, the Extremely Large Telescope.

The 4MOST Facility is a high-multiplex, wide-field, brief-fed spectrograph system for the ESO VISTA telescope. It aims to create a world-class spectroscopic survey facility unique in its combination of wide-field multiplex, spectral resolution, spectral coverage, and sensitivity. At the end of 2014, after a successful concept optimization design phase, 4MOST entered into its Preliminary Design Phase. Here we present the process and tools adopted during the Preliminary Design Phase to define the subsystems specifications, coordinate the interface control documents and draft the system verification procedures.

The 4MOST instrument is a multi-object-spectrograph for the ESO-VISTA telescope. The 4MOST fiber feed subsystem is composed of a fiber positioner (AESOP) holding 2436 science fibers based on the Echidna tilting spine concept, and the fiber cable, which feeds two low-resolution spectrographs (1624 fibers) and one high-resolution spectrograph (812 fibers). In order to optimize the fiber feed subsystem design and provide essential information required for the spectrograph design, prototyping and testing has been undertaken. In this paper we give an overview of the current fiber feed subsystem design and present the preliminary FRD, scrambling, throughput and system performance impact results for: maximum and minimum spine tilt, fiber connectors, cable de-rotator simulator for fiber cable lifetime tests.

After having demonstrated that an IFU, attached to a microscope rather than to a telescope, is capable of differentiating complex organic tissue with spatially resolved Raman spectroscopy, we have launched a clinical validation program that utilizes a novel optimized fiber-coupled multi-channel spectrograph whose layout is based on the modular MUSE spectrograph concept. The new design features a telecentric input and has an extended blue performance, but otherwise maintains the properties of high throughput and excellent image quality over an octave of wavelength coverage with modest spectral resolution. We present the opto-mechanical layout and details of its optical performance., Comment: 13 pages, 13 figures. Submitted in SPIE Astronomical Telescopes + Instrumentation, Paper No. 9912-72

Dynamic spectral analysis of astronomical events has the potential to deliver the information needed to clarify or complete important theoretical descriptions of astronomical phenomena. There is currently a lack of detailed sub-minute observations due to limitations in instruments and detectors. Here, we present an investigation into the feasibility of using fibre Bragg gratings (FBGs) as single-line spectral filters specifically for temporal spectral astronomy, attaining both a high spectral and fast temporal resolution simultaneously. We present the device concept and discuss it in the context of two readily available FBG profiles. We demonstrate that this instrument concept could resolve spectral shifts down to 0.02 nm (3.9 km s −1 ) with sub-second temporal resolution on a 4-m class telescope, which is far superior to existing techniques that attain resolutions of 0.05 nm over several minutes.

The Phase A design study of PILOT–the Pathfinder for an International Large Optical Telescope–has demonstrated that a wide-field 2.5 m optical/IR telescope can be constructed at Concordia for a reasonable cost. There are no technical “show stoppers”, and the cost of logistics is also quantifiable and reasonable. A strong science case has been developed and published as three separate papers. In order to proceed further, the next step is to undertake a detailed design study and identify potential manufacturers.

We present a Parkes multibeam H i survey of the Large Magellanic Cloud (LMC). This survey, which is sensitive to spatial structure in the range 200 pc ∼ 10 kpc, complements the Australia Telescope Compact survey, which is sensitive to structure in the range 15 pc ∼ 500 pc. With an rms column density sensitivity of 8 ×10 16 cm −2 for narrow lines and 4×10 17 cm −2 for typical linewidths of 40 km s −1 , emission is found to be extensive well beyond the main body of the LMC. Arm-like features extend from the LMC to join the Magellanic Bridge and the Leading Arm, a forward counterpart to the Magellanic Stream. These features, whilst not as dramatic as those in the SMC, appear to have a common origin in the Galactic tidal field, in agreement with recent 2MASS and DENIS results for the stellar population. The diffuse gas which surrounds the LMC, particularly at pa’s 90 ◦ to 330 ◦ , appears to be loosely associated with tidal features, but loosening by the ram pressure of tenuous Galactic halo gas against the outer parts of the LMC cannot be discounted. High-velocity clouds, which lie between the Galaxy and the LMC in velocity and which appear in the UV spectra of some LMC stars, are found to be associated with the LMC if their heliocentric velocity exceeds about +100 km s −1 . They are possibly the product of energetic outflows from the LMC disk. The H i mass of the LMC is found to be (4.8 ± 0.2) × 10 8 M⊙ (for an assumed distance of 50 kpc), substantially more than previous recent measurements.

4MOST,1 the 4m Multi-Object spectrographic Survey Telescope, is an upcoming optical, fiber-fed, MOS facility for the VISTA telescope at ESO's Cero Paranal Observatory (Chile). The preliminary design of 4MOST features 2,400 fibers split into a low-resolution (1,600 fibers, 390-900 nm, R > 5; 000) and a high-resolution channel (800 fibers, three arms, ~20-25 nm coverage each, R > 18; 000) with an Echidna-style positioner, and covering a hexagonal field of view of ~4.1 sqdeg. 4MOST's main science goals encompass massive (tens of millions of spectra), all-Southern sky (> 18; 000 sqdeg) surveys following up both the Gaia (optical) and eROSITA (X-ray) space missions, plus cosmological science that complements missions such as e.g. Euclid. In a novel approach, observations of these science cases, which are very different from another, are to be carried out in parallel (i.e., simultaneously); thus, from the very different science requirements, key user requirements have to be identified, stringently formulated, and condensed into a coherent set of system specifications. Clearly, identifying common grounds and thereby significantly reducing complexity in both the formulated requirements and the final 4MOST facility, is a very challenging task. In this paper, we will present science and user requirements, and how the latter flow down from the former, and eventually further down to the system-specification level. Special emphasis will be put on the identification of key requirements and their validation and verification protocols, so that significant trade-offs can be done as early on in the design phase as possible, with as little impact as possible on the science capabilities upstream.

We present a new type of R-θ fiber actuator named PotsPos for multi-object astronomical spectroscopy. It was initially intended to use as an alternative positioner design for the 4-meter Multi-Object Spectroscopic Telescope (4MOST). Although another tilting spine technology developed by the Australian Astronomical Observatory (AAO) is currently chosen for the 4MOST, PotsPos design has some technical advantages over other positioning technologies and might therefore be an attractive choice for future spectrographs. The design would be similar in positioning capabilities to the tilting spine design but would not suffer from telecentricity and defocus errors. The mechanical design, suitable motors, computational results from dynamic simulations and finite element analyses are presented.

4MOST, the 4m Multi-Object Spectroscopic Telescope, features a 2.5 degree diameter field-of-view with ~2400 fibers in the focal plane that are configured by a fiber positioner based on the tilting spine principle (Echidna/FMOS) arranged in a hexagonal pattern. The fibers feed two types of spectrographs; ~1600 fibers go to two spectrographs with resolution R>5000 and ~800 fibers to a spectrograph with R>18,000. Part of the ongoing optimization of the fiber feed subsystem design includes early prototyping and testing of key components such as fiber connectors and fiber cable management. Performance data from this testing will be used in the 4MOST instrument simulator (TOAD) and 4MOST system design optimization. In this paper we give an overview of the current fiber feed subsystem design, simulations and prototyping plans.

The 4MOST([1]) instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the ESO VISTA telescope designed to perform a massive (initially >25x10(6) spectra in 5 years) combined all-sky public survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of galaxies, X-ray AGN/galaxy evolution to z similar to 5, Galactic X-ray sources and resolving the Galactic edge; Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of similar to 1600 targets at R similar to 5,000 from 390-900nm and similar to 800 targets at R>18,000 in three channels between similar to 395-675nm (channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of similar to 4.1 degrees2. The initial 5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: opto-mechanical, control, data management and operations concepts; and initial performance estimates.

4MOST is a wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of the European Southern Observatory (ESO). Its main science drivers are in the fields of galactic archeology, high-energy physics, galaxy evolution and cosmology. 4MOST will in particular provide the spectroscopic complements to the large area surveys coming from space missions like Gaia, eROSITA, Euclid, and PLATO and from ground-based facilities like VISTA, VST, DES, LSST and SKA. The 4MOST baseline concept features a 2.5 degree diameter field-of-view with similar to 2400 fibres in the focal surface that are configured by a fibre positioner based on the tilting spine principle. The fibres feed two types of spectrographs; similar to 1600 fibres go to two spectrographs with resolution R> 5000 (lambda similar to 390-930 nm) and similar to 800 fibres to a spectrograph with R> 18,000 (lambda similar to 392-437 nm & 515-572 nm & 605-675 nm). Both types of spectrographs are fixed-configuration, three-channel spectrographs. 4MOST will have an unique operations concept in which 5 year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure, resulting in more than 25 million spectra of targets spread over a large fraction of the southern sky. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept. 4MOST has been accepted for implementation by ESO with operations expected to start by the end of 2020. This paper provides a top-level overview of the 4MOST facility, while other papers in these proceedings provide more detailed descriptions of the instrument concept[1], the instrument requirements development[2], the systems engineering implementation[3], the instrument model[4], the fibre positioner concepts[5], the fibre feed[6], and the spectrographs[7].

Starbug is a new concept for a robotic positioning system able to deploy many payloads, such as pickoff optics, optical fibres, integral field units over the focal surface of a telescope. Aimed at addressing some of the weakness of current positioning systems, Starbug employs micro-robotic actuators to independently and simultaneously position multiple small payloads accurately on an arbitrarily large field plate. Targeted at offering a cost-effective positioning system for both optical and infrared instrumentation it is being developed to; operate in cryogenic environments, position to micron level resolution, simultaneous move arbitrary numbers of payloads and included micro-tracking for minor positional adjustments that could compensate for differential atmospheric refraction effects and instrument flexure.

GNOSIS has provided the first on-telescope demonstration of a concept to utilize complex aperioidc fiber Bragg gratings to suppress the 103 brightest atmospheric hydroxyl emission doublets between 1.47-1.7 μm. The unit is designed to be used at the 3.9-meter Anglo-Australian Telescope (AAT) feeding the IRIS2 spectrograph. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion. We present the results of laboratory and on-sky tests from instrument commissioning. These tests reveal excellent suppression performance by the gratings and high inter-notch throughput, which combine to produce high fidelity OH-free spectra.

We discuss the development of multi-core fiber Bragg gratings (FBGs) to be applied to astrophotonics, more specifically to near-infrared spectroscopy for ground-based instruments. The multi-core FBGs require over 100 notches to reject the OH lines in a broad wavelength range (160 nm). The number of cores of the fiber should correspond to the mode number in the multi-mode fibers and should be large enough to be able to capture a sufficient amount of light from the telescope. A phase-mask based technique is used to fabricate the multi-core FBGs.

The 4MOST consortium is currently halfway through a Conceptual Design study for ESO with the aim to develop a wide-field (>3 square degree, goal >5 square degree), high-multiplex (>1500 fibres, goal 3000 fibres) spectroscopic survey facility for an ESO 4m-class telescope (VISTA). 4MOST will run permanently on the telescope to perform a 5 year public survey yielding more than 20 million spectra at resolution R~5000 (��=390-1000 nm) and more than 2 million spectra at R~20,000 (395-456.5 nm & 587-673 nm). The 4MOST design is especially intended to complement three key all-sky, space-based observatories of prime European interest: Gaia, eROSITA and Euclid. Initial design and performance estimates for the wide-field corrector concepts are presented. We consider two fibre positioner concepts, a well-known Phi-Theta system and a new R-Theta concept with a large patrol area. The spectrographs are fixed configuration two-arm spectrographs, with dedicated spectrographs for the high- and low-resolution. A full facility simulator is being developed to guide trade-off decisions regarding the optimal field-of-view, number of fibres needed, and the relative fraction of high-to-low resolution fibres. Mock catalogues with template spectra from seven Design Reference Surveys are simulated to verify the science requirements of 4MOST. The 4MOST consortium aims to deliver the full 4MOST facility by the end of 2018 and start delivering high-level data products for both consortium and ESO community targets a year later with yearly increments., To appear in the proceedings of the SPIE Astronomical Instrumentation + Telescopes conference, Amsterdam, 2012. 15 pages, 16 figures

GNOSIS is an instrument currently being commissioned at the Anglo-Australian Telescope that is designed to suppress atmospheric OH emission using fibre Bragg gratings. Here we present an outline of the GNOSIS instrument and the first on-telescope results from this new technology concept.

Over the years Photonics technologies have mainly been developed to satisfy the ever increasing demand for high-bandwidth/bit-rates imposed by mass media in general, with low losses and costs. These communication technology applications have been developed around an optical communication window centred at 1550nm wavelength with a span of ∼ 40nm, taking advantage of the low losses of silica optical fibres in this region. It is a great challenge to tailor these existing photonics technologies for use in Astrophysics or Astronomy (Astrophotonics) where an ultra-wide wavelength range spanning from ∼ 400–2000nm, with low losses and costs, is required. We present the ongoing developments at innoFSPEC to use integrated photonics (IPs) beyond communication to solve the scaling problem of conventional astronomical instruments (growth of instrument size in proportion to telescope aperture D and the increase of cost as D2 [1]). We will also exploit the miniature form of the multifunctional integrated planar light wave circuit to offer high stability, low sensitivity to vibrations and temperature fluctuations with low maintenance costs. One of the key devices that we envisage to design and fabricate with proper choice of material system is an Integrate Photonic Spectrograph (IPS) to disperse faint optical signals received from telescopes and project the output spectrum on to the detector with properly design optical element to achieve required spatial resolution. Moreover, UV-induced Bragg-grating inscription technology on planar IPs [2] could be used to fabricate integrated optical filters to suppress unwanted background [1] and further enhance the compactness, reduce cost, and increase the stability against environmental perturbations of these devices.

We report on the technological achievements of our latest Starbug prototypes and their implications for smart focal plane fiber positioning applications for wide-field astronomy. The Starbugs are innovative self-motile miniature robotic devices that can simultaneously and independently position fibers or payloads over a field plate located at the telescope's focal plane. The Starbugs concept overcomes many of the limitations associated with the traditional 'pick and place' positioners where a robot places fixed buttons onto the field plate. The new Starbug prototypes use piezoelectric actuators and have the following features: (i) new 'lift-and-step' method (discrete step) for accurate positioning over different surfaces; and (ii) operate in an inverted hanging position underneath a transparent field plate, removing the need for fibercable retractors. In this paper, we present aspects of the Starbug prototypes, including the theoretical model, mechanical design, experimental setup, algorithms, performance and applications for astronomical instrumentation.

We present the first integrated multimode photonic spectrograph, a device we call PIMMS #1. The device comprises a set of multimode fibres that convert to single-mode propagation using a matching set of photonic lanterns. These feed to a stack of cyclic array waveguides (AWGs) that illuminate a common detector. Such a device greatly reduces the size of an astronomical instrument at a fixed spectroscopic resolution. Remarkably, the PIMMS concept is largely independent of the telescope diameter, input focal ratio and entrance aperture – i.e. one size fits all! The instrument architecture can also exploit recent advances in astrophotonics (e.g . OH suppression fibres). We present a movie of the instrument’s operation and discuss the advantages and disadvantages of this approach. Keywords: multimode fibre; integrated photonic spectrograph; astronomical instrumentation – diffraction limited 1. INTRODUCTION In 2006, we explored the possibility of designing and building an integrated photonic spectrograph for the first time (Bland-Hawthorn & Horton 2006; hereafter BH06). The stated goals in that paper were to revolutionize our approach to instrument building in order to halt the spiraling trends in instrument development. In the following year, such a device was made to operate with a single-mode fibre input (Fig. 1; Bland-Hawthorn & Horton 2007). In 2008, the instrument was used successfully at Siding Spring Observatory, NSW which led to the first continuous spectrum ever obtained with a photonic device (Cvetojevic et al 2009). As anticipated, the coupling efficiency of diffuse incoherent skylight was very low but we still managed to observe the familiar OH atmospheric lines across the H band. For this technology to be viable on front-line telescopes, it is imperative that we extend it to accept light from a multimode fibre. This is a more challenging prospect that has not been solved until now. In solving this problem, we arrive at a device – PIMMS #1 – with revolutionary properties as we show. In principle, the PIMMS instrument will accept light from (almost) any input f/ratio, either natural seeing or AO-corrected, any input fibre diameter, and any telescope diameter. For spectroscopic resolutions in the range of 100s to a few u 10

Astrophotonics offers a solution to some of the problems of building instruments for the next generation of telescopes through the use of photonic devices to miniaturise and simplify instruments. It has already proved its worth in interferometry over the last decade and is now being applied to nightsky background suppression. Astrophotonics offers a radically different approach to highly-multiplexed spectroscopy to the benefit of galaxy surveys such as are required to determine the evolution of the cosmic equation of state. The Astrophotonica Europa partnership funded by the EU via OPTICON is undertaking a wide-ranging survey of the technological opportunities and their applicability to high-priority astrophysical goals of the next generation of observatories. Here we summarise some of the conclusions.

The size of the optical elements (gratings, mirrors, lenses) in traditional astronomical spectrographs scales with telescope diameter (unless the instrument is operating at the diffraction limit). For large telescopes, this leads to spectrographs of enormous size and implied cost. The integrated photonic spectrograph offers the potential to break this scaling law and allow massively multiplexed instruments. One proposed format for such a spectrograph recently demonstrated on-sky employs the arrayed-waveguide grating, which creates dispersion using interference between a series of waveguides with precisely defined length increments. Arrayed-waveguide gratings fabricated via planar techniques are used extensively in the telecommunications industry as optical (de)multiplexers. Current commercial devices are not directly applicable for astronomical use, and several design modifications are thus required. Here we investigate the potential capabilities and limitations of arrayed-waveguide grating technology to provide massively multiplexed spectroscopy for astronomy. In particular, we examine the dependence of the arrayed-waveguide grating design parameters (such as focal length, device order, array spacing, array length increment, refractive index contrast, chip size, number and structure of input modes, and configuration of output imaging or cross-dispersive optics) on the characteristics of the device output (operating wavelength, free spectral range, spectral resolution, multiplexing capacity, and number of required detector pixels).

GNOSIS is an OH suppression unit to be used in conjunction with existing spectrographs. The OH suppression is achieved using fibre Bragg gratings (FBGs), and will deliver the darkest near-infrared background of any ground-based instrument. Laboratory and on-sky tests demonstrate that FBGs can suppress OH lines by 30dB whilst maintaing > 90% throughput between the lines, resulting in a 4 mag decrease in the background. In the first implementation GNOSIS will feed IRIS2 on the AAT. It will consist of a seven element lenslet array, covering 1.4" on the sky, and will suppress the 103 brightest OH lines between 1.47 and 1.70 μm. Future upgrades will include J-band suppression and implementation on an 8m telescope.

The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of a baseline build of 150 identical spectrographs (arrayed as 75 units, each with a pair of spectrographs) fed by 33,600 fibers, each 1.5 arcsec diameter, deployed over the 22 arcminute field of the upgraded 10 m Hobby-Eberly Telescope (HET). The goal is to deploy 96 units. VIRUS has a fixed bandpass of 350-550 nm and resolving power R~700. VIRUS is the first example of industrial-scale replication applied to optical astronomy and is capable of spectral surveys of large areas of sky. The method of industrial replication, in which a relatively simple, inexpensive, unit spectrograph is copied in large numbers, offers significant savings of engineering effort, cost, and schedule when compared to traditional instruments. The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX+) using 0.8M Lyman-α emitting galaxies as tracers. The full VIRUS array is due to be deployed in late 2011 and will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope. VIRUS and HET will open up wide field surveys of the emission-line universe for the first time. We present the design, cost, and current status of VIRUS as it enters production, and review performance results from the VIRUS prototype. We also present lessons learned from our experience designing for volume production and look forward to the application of the VIRUS concept on future extremely large telescopes (ELTs).

PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed 2.5 m optical/infrared telescope to be located at Dome C on the Antarctic plateau. Conditions at Dome C are known to be exceptional for astronomy. The seeing (above ~30 m height), coherence time, and isoplanatic angle are all twice s good as at typical mid-latitude sites, while the water-vapour column, and the atmosphere and telescope thermal emission are all an order of magnitude better. These conditions enable a unique scientific capability for PILOT, which is addressed in this series of papers. The current paper presents an overview of the optical and instrumentation suite for PILO and its expected performance, a summary of the key science goals and observational approach for the facility, a discussion of the synergies between the science goals for PILOT and other telescopes, and a discussion of the future of Antarctic astronomy. Paper II and Paper III present details of the science projects divided, respectively, between the distant Universe (i.e., studies of first light, and the assembly and evolution of structure) and the nearby Universe (i.e., studies of Local Group galaxies, the Milky Way, and the Solar System)., 19 pages, 8 figures, accepted for publication in PASA

We present results from the first on-sky demonstration of a prototype astronomical integrated photonic spectrograph (IPS) using the Anglo-Australian Telescope near-infrared imaging spectrometer (IRIS2) at Siding Spring Observatory to observe atmospheric molecular OH emission lines. We have succeeded in detecting upwards of 27 lines, and demonstrated the practicality of the IPS device for astronomy. Furthermore, we present a laboratory characterization of the device, which is a modified version of a commercial arrayed-waveguide grating multiplexer. We measure the spectral resolution full-width-half-maximum to be 0.75 +/- 0.05 nm (giving R = lambda/deltalambda = 2100 +/- 150 at 1500 nm). We find the free spectral range to be 57.4 +/- 0.6 nm and the peak total efficiency to be approximately 65%. Finally, we briefly discuss the future steps required to realize an astronomical instrument based on this technology concept.

PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed Australian/European optical/infrared telescope for Dome C on the Antarctic Plateau, with target first light in 2012. The telescope is 2.4m diameter, with overall focal ratio f/10, and a 1 degree field-of-view. It is mounted on a 30m tower to get above most of the turbulent surface layer, and has a tip-tilt secondary for fast guiding. In median seeing conditions, it delivers 0.3" FWHM wide-field image quality, from 0.7-2.5 microns. In the best quartile of conditions, it delivers diffraction-limited imaging down to 1 micron, or even less with lucky imaging. The major challenges have been (a) preventing frost-laden external air reaching the optics, (b) overcoming residual surface layer turbulence, (c) keeping mirror, telescope and dome seeing to acceptable levels in the presence of large temperature variations with height and time, (d) designing optics that do justice to the site conditions. The most novel feature of the design is active thermal and humidity control of the enclosure, to closely match the temperature of external air while preventing its ingress.

Mapping out stellar families to trace the evolutionary star formation history of the Milky Way requires a spectroscopic facility able to deliver high spectral resolution (R≥30k) with both good wavelength coverage (~400 Ang) and target multiplex advantage (~400 per 2 degree field). Such a facility can survey 1,200,000 bright stars over 10,000 square degrees in about 400 nights with a 4-meter aperture telescope. Presented are the results of a conceptual design study for such a spectrograph, which is under development as the next major instrument for the Anglo-Australian Observatory. The current design (that builds upon the AAOmega system) makes use of a White Pupil collimator and an R3 echelle that is matched to the existing AAOmega cameras. The fibre slit can be reconfigured to illuminate the Pupil relay side of the collimator mirror bypassing the echelle, thus preserving the lower dispersion modes of the AAOmega spectrograph. Other spectrograph options initially considered include use of an anamorphic collimator that reduces the required dispersion to that achievable with VPH grating technology or possible use of a double-pass VPH grating.

We present FLEX, an instrument to demonstrate the power of “bre Bragg grating OH suppression. This groundbreaking technology promises great gains in sensitivity for near infrared instrumentation and the time is nowright for a pioneer instrument to prove the eectiveness of the technique. Our proposal is for an adaptive opticsfed integral “eld unit for an 8 metre class telescope. We envisage a 61 element IFU with 0.22 sampling and a2.2 “eld of view. J and H-band OH suppression units would cleanly suppress the atmospheric emission lines,eectively lowering the sky background by 3 or 4 magnitudes respectively. The capabilities of FLEX will makeit ideal for deep Epoch of Reionisation studies, as well as studies of star formation at z 1 4. To enable rapidand economical deployment FLEX would use an existing near infrared spectrograph with R 1000 and employfacility adaptive optics.Keywords: FLEX, OH suppression, “bre Bragg grating, photonic lantern, adaptive optics, integral “eld spec-troscopy, near infrared

PILOT (the Pathfinder for an International Large Optical Telescope) is a proposed Australian/European optical/infrared telescope for Dome C on the Antarctic Plateau, with target first light in 2012. The proposed telescope is 2.4m diameter, with overall focal ratio f/10, and a 1 degree field-of-view. In median seeing conditions, it delivers 0.3" FWHM wide-field image quality, from 0.7-2.5 microns. In the best quartile of conditions, it delivers diffraction-limited imaging down to 1 micron, or even less with lucky imaging. The areas where PILOT offers the greatest advantages are (a) very high resolution optical imaging, (b) high resolution wide-field optical imaging, and (c) all wide-field thermal infrared imaging. The proposed first generation instrumentation consists of (a) a fast, low-noise camera for diffraction-limited optical lucky imaging; (b) a gigapixel optical camera for seeing-limited imaging over a 1 degree field; (c) a 4K x 4K near-infrared (1-5 micron) camera with both wide-field and diffraction-limited modes; and (d) a double-beamed midinfrared (7-40 micron) camera.

We explore the range of wide field multi-object instrument concepts taking advantage of the unique capabilities of the Starbug focal plane positioning concept. Advances to familiar instrument concepts, such as fiber positioners and deployable fiber-fed IFUs, are discussed along with image relays and deployable active sensors. We conceive deployable payloads as components of systems more traditionally regarded as part of telescope systems rather than instruments - such as adaptive optics and ADCs. Also presented are some of the opportunities offered by the truly unique capabilities of Starbug, such as microtracking to apply intra-field distortion correction during the course of an observation., Comment: 12 pages, 8 figures, to be published in Proc. SPIE 6273 "Opto-Mechanical Technologies for Astronomy"

AAOmega is the new spectrograph for the 2dF fibre-positioning system on the Anglo-Australian Telescope. It is a bench-mounted, double-beamed design, using volume phase holographic (VPH) gratings and articulating cameras. It is fed by 392 fibres from either of the two 2dF field plates, or by the 512 fibre SPIRAL integral field unit (IFU) at Cassegrain focus. Wavelength coverage is 370 to 950nm and spectral resolution 1,000-8,000 in multi-Object mode, or 1,500-10,000 in IFU mode. Multi-object mode was commissioned in January 2006 and the IFU system will be commissioned in June 2006. The spectrograph is located off the telescope in a thermally isolated room and the 2dF fibres have been replaced by new 38m broadband fibres. Despite the increased fibre length, we have achieved a large increase in throughput by use of VPH gratings, more efficient coatings and new detectors - amounting to a factor of at least 2 in the red. The number of spectral resolution elements and the maximum resolution are both more than doubled, and the stability is an order of magnitude better. The spectrograph comprises: an f/3.15 Schmidt collimator, incorporating a dichroic beam-splitter; interchangeable VPH gratings; and articulating red and blue f/1.3 Schmidt cameras. Pupil size is 190mm, determined by the competing demands of cost, obstruction losses, and maximum resolution. A full suite of VPH gratings has been provided to cover resolutions 1,000 to 7,500, and up to 10,000 at particular wavelengths., 13 pages, 4 figures; presented at SPIE, Astronomical Telescopes and Instrumentation, 24 - 31 May 2006, Orlando, Florida USA

AAOmega is a new spectrograph for the existing 2dF and SPIRAL multifibre systems on the Ango-Australian Telescope. It is a bench-mounted, dual-beamed, articulating, all-Schmidt design, using volume phase holographic gratings. The wavelength range is 370-950nm, with spectral resolutions from 1400-10000. Throughput, spectral coverage, and maximum resolution are all more than doubled compared with the existing 2dF spectrographs, and stability is increased by orders of magnitude. These features allow entirely new classes of observation to be undertaken, as well as dramatically improving existing ones. AAOmega is scheduled for delivery and commissioning in Semester 2005B.

The AAOmega project replaces the two 2dF spectrographs, which are mounted on the top end of the Anglo Australian Telescope, with a bench mounted double beam spectrograph covering 370 to 950nm. The 2dF positioner, field plate tumbler mechanism, and fiber retractors will be retained. The new spectrograph will be fed by 392 fibers from either of the two 2dF field plates, or by the 512 fiber Spiral integral field unit, located at the Cassegrain focus. New instrument control electronics has also been designed to drive the spectrograph. Stability will be improved by locating the spectrograph off the telescope, but the 2df fibers must be extended to thirty-eight metres length. Despite this, using fibers with improved characteristics, increased pupil diameter, volume phase holographic (VPH) gratings with articulated cameras, and more efficient coatings on optics we achieve a minimum twofold increase in throughput. We will also fit larger (4k x 2k pixel) detectors. The spectrograph comprises: a F/3.15 Schmidt collimator, incorporating a dichroic beamsplitter; interchangeable VPH gratings; and articulating red and blue F/1.3 Schmidt cameras. The beamsplitter may be exchanged with others which cut off at different wavelengths. A full suite of VPH gratings are provided to cover resolution to 8000.

IRIS2, the infrared imager and spectrograph for the Cassegrain focus of the Anglo Australian Telescope, has been in service since October 2001. IRIS2 incorporated many novel features, including multiple cryogenic multislit masks, a dual chambered vacuum vessel (the smaller chamber used to reduce thermal cycle time required to change sets of multislit masks), encoded cryogenic wheel drives with controlled backlash, a deflection compensating structure, and use of teflon impregnated hard anodizing for gear lubrication at low temperatures. Other noteworthy features were: swaged foil thermal link terminations, the pupil imager, the detector focus mechanism, phased getter cycling to prevent detector contamination, and a flow-through LN2 precooling system. The instrument control electronics was designed to allow accurate positioning of the internal mechanisms with minimal generation of heat. The detector controller was based on the AAO2 CCD controller, adapted for use on the HAWAII1 detector (1024 x 1024 pixels) and is achieving low noise and high performance. We describe features of the instrument design, the problems encountered and the development work required to bring them into operation, and their performance in service.

Recently integral field spectroscopy has become a band-wagon among the optical astronomical community and most of the 8m class telescopes plan to offer this as part of their instrumentation package. The possibility of expanding integral field spectroscopy into the near infrared (1-2.5μm) opens exciting new possibilities for the study of a variety of astronomical objects. In this paper, we discuss some of the design requirements for the proposed Gemini Infra-Red Multi-Object Spectrograph (GIRMOS) and sky subtraction techniques suitable for infrared fibre spectroscopy. We address the performance of optical fibres suitable for use from 1-2.5μm and the effects of cooling these fibres to liquid nitrogen temperatures (∼77°K) including: focal ratio degradation (FRD), fibre transmission and thermal emissivity, mechanical properties and durability. Also discussed are issues related to sky subtraction for IR fibre spectroscopy such as: dedicated sky fibres, dedicated sky d-IFUs, and various beam switching methods. This work is all part of a development study for multiple deployable integral field units (d-IFUs) for GIRMOS.

The SMIRFS prototype near IR fiber system has been designed to provide a multi-object capability in the J, H and K bands and an integral field capability from 1 to 2 micrometers in conjunction with the cooled grating spectrograph CGS4 at the UKIRT. In multi-object mode there are 14 fibers covering a 12 arcmin 2 field and in integral field mode there are 72 fibers covering a 6 X 4 arcsec field with spatial sampling of 0.63 arcsec. Both modes use fibers that are coupled to the telescope and spectrograph using lenslets. The information gleaned from these devices should benefit the next generation of IR spectrographs that will take full advantage of the larger chip formats that are now coming on line.

One of the most exciting operational modes of the new generation of 8-m class telescopes will be integral field spectroscopy. Many of the current designs of integral field units use microlens arrays as a way of sampling the focal plane of the telescope. Integral field spectroscopy places demanding requirements on the optical quality of the microlens arrays. In this paper we describe these requirements and report on an extensive series of optical tests to characterize microlens arrays in the laboratory. The tests were carried out on prototype microlens arrays intended for use in various Durham instrument projects. The lenses tested had excellent positional accuracy and consistency of focal length. However detailed measurements of the point spread function showed a core with good image quality but with a background level of diffuse scattered light. This scattered light causes a throughput loss in the instrument of around approximately 20%. This result was verified for the Spectroscopic Multimode InfraRed Fiber System (SMIRFS) integral field unit by absolute throughput tests carried out during commissioning of the instrument at the United Kingdom Infrared Telescope.

As the only two optical instruments appearing in its first fleet of instrumentation, the GEMINI MultiObject Spectrograph (GMOS) are indeed being developed as workhorse instruments. One GMOS will be located at each of the GEMINI telescopes to perform: (1) exquisite direct imaging, (2) 5.5 arcminute longslit spectroscopy, (3) up to 600 object multislit spectroscopy, and (4) about 2000 element integral field spectroscopy. The GMOSs are the only GEMINI instrumentation duplicated at both telescopes. The UK and Canadian GMOS team successfully completed their critical design review in February 1997. They are now well into the fabrication phase, and will soon approach integration of the first instrument. The first GMOS is scheduled to be delivered to Mauna Kea in the fall of '99 and the second to Cerro Pachon one year later. In this paper, we will look at how a few of the more interesting details of the final GMOS design help meet its demanding scientific requirements. These include its transmissive optical design and mask handling mechanisms. We will also discuss our plans for the mask handling process in GEMINI's queue scheduled environment, from the taking of direct images through to the use of masks on the telescope. Finally, we present the status of fabrication and integration work to date.

GNOSIS is a prototype astrophotonic instrument that utilizes OH suppression fibres consisting of fibre Bragg gratings and photonic lanterns to suppress the 103 brightest atmospheric emission doublets between 1.47-1.7 microns. GNOSIS was commissioned at the 3.9-meter Anglo-Australian Telescope with the IRIS2 spectrograph to demonstrate the potential of OH suppression fibres, but may be potentially used with any telescope and spectrograph combination. Unlike previous atmospheric suppression techniques GNOSIS suppresses the lines before dispersion and in a manner that depends purely on wavelength. We present the instrument design and report the results of laboratory and on-sky tests from commissioning. While these tests demonstrated high throughput and excellent suppression of the skylines by the OH suppression fibres, surprisingly GNOSIS produced no significant reduction in the interline background and the sensitivity of GNOSIS and IRIS2 is about the same as IRIS2. It is unclear whether the lack of reduction in the interline background is due to physical sources or systematic errors as the observations are detector noise-dominated. OH suppression fibres could potentially impact ground-based astronomy at the level of adaptive optics or greater. However, until a clear reduction in the interline background and the corresponding increasing in sensitivity is demonstrated optimized OH suppression fibres paired with a fibre-fed spectrograph will at least provide a real benefits at low resolving powers., 15 pages, 13 figures, accepted to AJ

We describe an IR multi-fibre system we are currently building for UKIRT. SMIRFS (Spectroscopic multiple infrared fibre system) will feed the CGS4 spectrograph, providing it with a multi-object capability in the J, H and K bands. For efficient coupling the inputs and outputs of the fibres are microlensed. Because the telescope is normally focused inside CGS4 for conventional spectroscopy the SMIRFS fibre slit is projected in to CGS4 by a spherical mirror. IR optimised Silica fibres are used for the J and H bands and Zirconium Fluoride fibres are used for the K band.

We present an overview of the 4MOST project at the Preliminary Design Review. 4MOST is a major new wide-field, high-multiplex spectroscopic survey facility under development for the VISTA telescope of ESO. 4MOST has a broad range of science goals ranging from Galactic Archaeology and stellar physics to the high-energy physics, galaxy evolution, and cosmology. Starting in 2021, 4MOST will deploy 2436 fibres in a 4.1 square degree field-of-view using a positioner based on the tilting spine principle. The fibres will feed one high-resolution (R similar to 20,000) and two medium-resolution (R similar to 5000) spectrographs with fixed 3-channel designs and identical 6k x 6k CCD detectors. 4MOST will have a unique operations concept in which 5-year public surveys from both the consortium and the ESO community will be combined and observed in parallel during each exposure. The 4MOST Facility Simulator (4FS) was developed to demonstrate the feasibility of this observing concept, showing that we can expect to observe more than 25 million objects in each 5-year survey period and will eventually be used to plan and conduct the actual survey.

The next generation of major ground-based optical and near-infrared astronomical telescopes are planned to have aperture sizes from 25–42 meters in diameter, making them substantially larger than existing telescopes. This has a major impact on seeing limited spectroscopic instrumentation, as the size of the instrument grows in proportion to the telescope aperture for traditional designs and more importantly, the cost of the instrument increases with the telescope aperture squared, or faster [1]. This unsustainable trend has necessitated a miniaturization of devices for astronomy, with integrated photonics showing great promise. Particularly of interest is the integrated photonic spectrograph (IPS) [1,2].