The Veloce spectrograph is a high resolution (R > 75000), compact, highly-stabilised, and hyper-calibrated echelle spectrograph to obtain Doppler velocities for Sun-like and M-dwarf at < 1 ms−1. This spectrograph was built utilising multiple innovations to provide a “just -enough-stabilisation” platform, compensating the science observations with simultaneous collected data from an ultra-stabilised calibration source. The spectrograph consists of three spectral arms, one of which has been in operation while the additional two arms were undergoing construction. The first arm of the spectrograph, the Rosso arm, has a wavelength coverage of 580-930 nm was installed at the Anglo-Australian Telescope (AAT) and saw first light in September 2018. The Verde, 434-593 nm, and Azzurro, 378-437 nm, spectral arms passed the final design review in February of 2021 and were installed May and June of 2023 with first light occurring in early July 2023. This paper presents a review of the upgrade project along with discussions on the mechanical and optical designs in terms of procurement and manufacturability. We discuss the changes to the instrument driven from the lessons learned during the construction of the first arm of the spectrograph including detector electronics, optical mounts, and infrastructure, also the provisional acceptance of the installed instrument. We also include a discussion on the determination of the very tight slope error tolerances for the aspheric lenses in order to limit the influence of the mid-spatial frequencies on the spectra presented to the detector.
Detector modeling is becoming more and more critical for the development of new instruments in scientific space missions and ground-based experiments. Modeling tools are often developed from scratch by each individual project and not necessarily shared for reuse by a wider community. To foster knowledge transfer, reusability, and reliability in the instrumentation community, we developed Pyxel, a framework for the simulation of scientific detectors and instruments. Pyxel is an open-source and collaborative project, based on Python, developed as an easy-to-use tool that can host and pipeline any kind of detector effect model. Recently, Pyxel has achieved a new milestone: the public release and launch of version 1.0, which simplified third-party contributions and improved ease of use even further. Since its launch, Pyxel has been experiencing a growing user community and is being used to simulate a variety of detectors. We give a tour of Pyxel’s version 1.0 changes and new features, including a new interface, parallel computing, and new detectors and models. We continue with an example of using Pyxel as a tool for model optimization and calibration. Finally, we describe an example of how Pyxel and its features can be used to develop a full-scale end-to-end instrument simulator.
KEYWORDS: Sensors, Interfaces, Thermal modeling, Tolerancing, Manufacturing, Temperature metrology, Design for manufacturability, Finite element methods, Signal detection, Aluminum
Leonardo partnered with the Institute for Astronomy (IfA), University of Hawaii to develop a 1K x 1K infrared avalanche photo diode suitable for low background science applications. Presented here is the design and thermal modeling for the Kovar carrier for mounting the detector as well as the challenges faced in designing and manufacturing the complex flex cable. The flex cable provides the 68 bond pads necessary to service the detector in a width of just over 17mm as well as providing filtering for the bias supplies. The final package is a compact, three side buttable package that has been successfully tested at an operating temperature of 80K.
Starbugs are self-motile fibre optic positioning robots developed by AAO-MQ. MANIFEST (MANy Instrument FibrE SysTem) is a facility class Instrument which will operate up to 900 Starbugs on the Giant Magellan Telescope (GMT). The FOBOS (Fibre-Optic Broadband Optical Spectrograph) Fibre Positioner is a facility class Instrument which will operate up to 1800 Starbugs on the Keck Telescope. Starbugs deliver an optical payload to the location of an astronomical object on the telescope focal plane. The Starbugs are made from a pair of concentric Piezoceramic Tubes (PZT), and a high-voltage waveform is applied to the PZT to create an actuation. Staging of the waveform creates successive microsteps, on the order of 3-20 μm each, at a driven frequency of 100Hz. The Starbugs are adhered to the Glass Field Plate (GFP) using an ancillary vacuum system, which must provide sufficient adhesion force to maintain the Starbug GFP position in the high-altitude environmental conditions at Mauna Kea (MKO) and Las Campanas Observatory (LCO) sites. The minimum vacuum adhesion requirements to achieve Starbug GFP position were used to specify the vacuum pump flow rate and operational head pressure. The vacuum adhesion requirements were experimentally obtained using the Starbug Test Stand, located in Sydney, Australia. The Starbugs Test Stand vacuum adhesion requirements were parametised for dry air mass flow rate and head pressure, and then corrected for the 95th percentile environmental conditions at MKO and LCO. The vacuum system numerical model was verified by the TAIPAN instrument. When corrected for ambient atmospheric conditions at the UK Schmidt Telescope (Siding Spring Observatory, Australia), the numerical model could predict the steady state vacuum pump speed with 1.29% variation from the measured vacuum pump speed recorded by the TAIPAN Instrument control software. This capability of the numerical model will be used for real-time condition monitoring of the Starbugs Instruments.
The 4m DAG telescope is under construction at East Anatolia Observatory in Turkey. DIRAC, the “DAG InfraRed Adaptive optics Camera”, is one of the facility instruments. This paper describes the design of the camera to meet the performance specifications. Adaptive and auxiliary optics relay the telescope F/14 input 1:1 into DIRAC. The camera has an all refractive design for the wavelength range 0.9 - 2.4 micron. Lenses reimage the telescope focal plane 33 x 33 as (9 x 9 mm) on a 1k x 1k focal plane array. With magnification of 2x, the plate scale on the detector is 33 mas/pixel. There are 4 standard filters (Y, J, H, K) and 4 narrowband continuum filters. A 12 position filter wheel allows installation of 2 extra customer filters for specific needs; the filter wheel also deploys a pupil viewer lens. Optical tolerancing is carried out to deliver the required image quality at polychromatic Strehl ratio of 90% with focus compensator. This reveals some challenges in the precision assembly of optics for cryogenic environments. We require cells capable of maintaining precision alignment and keeping lenses stress free. The goal is achieved by a combination of flexures with special bonding epoxy matching closely the CTE of the lens cells and crystalline materials. The camera design is very compact with object to image distance <220 mm and lens diameters <25 mm. A standalone cryostat is LN2 cooled for vibration free operation with the bench mounted adaptive optics module (TROIA) and coronagraph (PLACID) at the Nasmyth focus of the DAG telescope.
Starbugs are self-motile fibre optic positioning robots developed by AAO-MQ. The MANIFEST (MANy Instrument FibrE SysTem) is a facility class Instrument which will operate up to 900 Starbugs on the Giant Magellan Telescope (GMT). The FOBOS (Fibre-Optic Broadband Optical Spectrograph) Fibre Positioner is a facility class Instrument which will operate up to 1800 Starbugs on the Keck Telescope. The Starbugs deliver an optical payload to the location of an astronomical object on the telescope focal plane. The Starbugs are made from a pair of concentric Piezoceramic Tubes (PZT), and a high-voltage waveform is applied to the PZT to create an actuation. Staging of the waveform creates successive microsteps, on the order of 3-20 μm each, at a driven frequency of 100Hz. The Starbugs are adhered to the Glass Field Plate (GFP) using an ancillary vacuum system. The Starbugs have an airtight vacuum sealing component between the PZT and the GFP, called Slippers, which serve as a traction surface against the polished GFP. The Slippers set the science fibre focus offset, which has functional requirements that trace to Observatory level requirements. The Slipper components are subject to non-zero centred fully reversed fatigue loading due to the combined load case of the vacuum induced compression and the shear load of the PZT actuation as the Starbug completes the step. The contact interface between the Slipper and the GFP is subject to surface fatigue and functions as a sacrificial wear surface to ensure the longevity of both the PZT and the optical payload. The fatigue life behaviour of the Slipper, with particular interest on this interface, was defined using industry standard methods and informed the trade study to select the appropriate material for the Slippers to survive a nominal period on-sky (fatigue life). The trade study terms were vacuum sealing ability as a function of mechanical hardness versus fatigue life (108 cycles). Several suitable materials were identified and will be physically prototyped, with results reported in this manuscript.
Detector modelling is becoming more and more critical for the successful development of new instruments in scientific space missions and ground-based experiments. Specific modelling tools are often developed from scratch by each individual project and not necessarily shared for reuse by a wider community. To foster knowledge transfer, reusability and reliability in the instrumentation community, ESA and ESO joined forces and developed Pyxel, a framework for the simulation of scientific detectors and instruments. Pyxel is an open-source and collaborative project, based on Python, developed as an easy-to-use tool that can host and pipeline any kind of detector effect model. Recently Pyxel has achieved a new milestone: the public release and launch of version 1.0 which simplified third-party contributions and improved ease of use even further. Since its launch, Pyxel has been experiencing a growing user community and is being used to simulate all kinds of detectors beyond the traditional Charged-Coupled Devices and CMOS devices, for example Microwave Kinetic Inductance Detectors (MKID) and Avalanche Photo Diode (APD) devices. We give a tour of Pyxel’s version 1.0 changes and new features including a new interface, parallel computing, and new detectors and models. We continue with an example of using Pyxel as a tool for model optimization and calibration. Finally, we describe an example of how Pyxel and its features can be used to develop a full-scale end-to-end instrument simulator.
KEYWORDS: Stars, Sensors, Infrared radiation, Infrared imaging, Telescopes, Absorption, Space operations, Infrared telescopes, Infrared detectors, Signal to noise ratio
A wide-field zenith-looking telescope operating in a mode similar to time-delay-integration (TDI) or drift scan imaging can perform an infrared sky survey without active pointing control, but it requires a high-speed, low-noise infrared detector. Operating from a hosted payload platform on the International Space Station (ISS), the Emu space telescope employs the paradigm-changing properties of the Leonardo SAPHIRA electron avalanche photodiode array to provide powerful new observations of cool stars at the critical water absorption wavelength (1.4 μm) largely inaccessible to ground-based telescopes due to the Earth’s own atmosphere. Cool stars, especially those of spectral-type M, are important probes across contemporary astrophysics, from the formation history of the Galaxy to the formation of rocky exoplanets. Main sequence M-dwarf stars are the most abundant stars in the Galaxy and evolved M-giant stars are some of the most distant stars that can be individually observed. The Emu sky survey will deliver critical stellar properties of these cool stars by inferring oxygen abundances via measurement of the water absorption band strength at 1.4 μm. Here, we present the TDI-like imaging capability of Emu mission, its science objectives, instrument details, and simulation results.
Cool stars, especially spectral-type M, are important probes across contemporary astrophysics, from the forma- tion history of the galaxy to the coalescence of rocky exoplanets. Main sequence M-dwarf stars are one of the most abundant stars in the galaxy, and evolved M-giant stars are some of the most distant stars that can be individually observed. The Emu sky survey, described here, will deliver critical stellar properties of these cool stars by inferring the oxygen abundance via measurement of the water band strength at 1.4 μm. A relatively wide field zenith-looking telescope with time delay integration capability can perform such a survey without active pointing but requires a fast and low-noise detector. Emu employs the paradigm-changing properties of the Leonardo SAPHIRA electron avalanche photodiode array, to provide these powerful new observations at the critical water absorption wavelength inaccessible to ground-based telescopes due to the Earth's own atmosphere. Here we will present Emu mission concept, science objectives, instrument details and simulation results.
KEYWORDS: Ultraviolet radiation, Astronomy, Earth's atmosphere, Atmospheric monitoring, Absorption, Near ultraviolet, Ozone, Solar processes, Signal to noise ratio, Wind energy
The ozone layer has a complex spectral absorption profile at NUV wavelengths. It is dependent on seasonal effects due to solar intensity, as well as atmospheric circulation of the ozone layer. Getting above this then becomes imperative for getting a usable SNR for scientific observations. GLUV is an affordable, long duration, high altitude balloon experiment which will fly a network of NUV telescopes at altitudes of 20-30 km. GLUV Pathfinder is a spectrometer based system to identify the sky background in the NUV, measuring this as a function of altitude, latitude, and seasonal phase in the regimes that the final GLUV project will experience. The development of dedicated NUV instrumentation is highly important for supernovae astronomy, as these higher energy wavelengths reveal their initial detonation conditions. GLUV is expected to capture the initial shocks of these events at a rate of 10+ per year of operation, well in excess of the few instances that have been seen to date
KEYWORDS: Visible radiation, James Webb Space Telescope, Observatories, Adaptive optics, Large telescopes, Spectrographs, Spatial resolution, Hubble Space Telescope, Telescopes
A consortium of several Australian and European institutes – together with the European Southern Observatory (ESO) – has initiated the design of MAVIS, a Multi-Conjugate Adaptive Optics (MCAO) system for the ground- based 8-m Very Large Telescope (VLT). MAVIS (MCAO-assisted Visible Imager and Spectrograph) will deliver visible images and integral field spectrograph data with 2-3x better angular resolution than the Hubble Space Telescope, making it a powerful complement at visible wavelengths to future facilities like the space-based James Webb Space Telescope and the 30 to 40m-class ground-based telescopes currently under construction, which are all targeting science at near-infrared wavelengths. MAVIS successfully passed its Phase A in May 2020. We present the motivations, requirements, principal design choices, conceptual design, expected performance and an overview of the exciting science enabled by MAVIS.
The MCAO Assisted Visible Imager and Spectrograph (MAVIS) is a facility-grade visible MCAO instrument, currently under development for the Adaptive Optics Facility at the VLT. The adaptive optics system will feed both an imager and an integral field spectrograph, with unprecedented sky coverage of 50% at the Galactic Pole. The imager will deliver diffraction-limited image quality in the V band, cover a 30" x 30" field of view, with imaging from U to z bands. The conceptual design for the spectrograph has a selectable field-of-view of 2.5" x 3.6", or 5" x 7.2", with a spatial sampling of 25 or 50 mas respectively. It will deliver a spectral resolving power of R=5,000 to R=15,000, covering a wavelength range from 380 - 950 nm. The combined angular resolution and sensitivity of MAVIS fill a unique parameter space at optical wavelengths, that is highly complementary to that of future next-generation facilities like JWST and ELTs, optimised for infrared wavelengths. MAVIS will facilitate a broad range of science, including monitoring solar system bodies in support of space missions; resolving protoplanetary- and accretion-disk mechanisms around stars; combining radial velocities and proper motions to detect intermediate-mass black holes; characterising resolved stellar populations in galaxies beyond the local group; resolving galaxies spectrally and spatially on parsec scales out to 50 Mpc; tracing the role of star clusters across cosmic time; and characterising the first globular clusters in formation via gravitational lensing. We describe the science cases and the concept designs for the imager and spectrograph.
KEYWORDS: Sensors, Photometry, Stars, Electronics, Image processing, Space operations, Earth's atmosphere, Field programmable gate arrays, Cryocoolers, Control systems design
‘Emu’ is a compact wide-field photometer destined for a 6-month mission on the exterior of the International Space Station (ISS), commencing in 2021. Emu will undertake a sky survey in the 1.4 μm ‘water band’, as a method of estimating oxygen abundance in the atmospheres of cool stars down to a magnitude of mAB≈13 (H-band).
Cryocoolers have long been demonstrated to be a dominant source of vibration that have caused significant problems with AO systems on large telescopes. Existing large telescopes have already imposed strict vibration requirements on instruments in response to existing problems, and have often struggled to achieve them. As the field moves into the next generation telescopes with GMT, TMT and eELT, vibration requirements continue to get ever tighter. Instrument teams must respond to these more demanding requirements by careful selection of cryocoolers and thoughtful design of cryocooler mounts that are matched closely with the specific requirements of the telescope. As we will demonstrate in this paper there is not a one-size-fits-all solution for every instrument and every telescope. In this paper we demonstrate a general method of deriving the required performance for an anti-vibration mounts for cryocoolers. First we characterize a linear Stirling-type cryocooler as a source of vibration, and determine what compliant mounts would be required to make them acceptable for use on the VLT, GMT and TMT. Measurements are taken of vibration from a Cryotel GT linear Stirling cooler (with active vibration cancellation enabled). By comparing the measured vibration against the requirements of each telescope, we are able to determine the required transfer function and therefore the required spring rate for compliant mounts. The results indicate that while some simple rubber mounts may be sufficient for use with the VLT and TMT, but a compliant mount with natural frequency below 14 Hz must be used for GMT.
GLUV is a balloon-based near UV survey telescope under development. The primary objective of GLUV is high- cadence observations of transient events such as early UV observations of supernova. The ozone layer absorbs a considerable amount of UV radiation, so it is important for a UV balloon telescope to achieve ight altitude above the ozone layer. The ozone layer density varies with respect to latitude, altitude and season. The structure and behaviour of ozone distribution is an important factor to be studied to account for astronomical ultraviolet observations. GLUV pathfinder is a spectrometer based system to identify the sky background at intended ight altitudes and atmosphere transmission GLUV will experience. In this presentation, we will present the design and development of the GLUV pathfinder system.
The Leonardo SAPHIRA is a HgCdTe linear avalanche photodiode array enabling high frame rate, high sensitivity, low noise, and low dark current imaging at near-infrared wavelengths. The ANU utilised the Leonardo SAPHIRA to develop a high cadence “Lucky Imager” which was successfully tested on sky at Siding Spring Observatory. The cryogenic electronics and cryostat were designed and built by the ANU. The cryostat was cooled with a compact Stirling cycle cryocooler with active vibration damping. Various detector control systems were tested, including an ESO 'NGC' system and also a 32 channel ARC SDSU Series III. Images were ultimately captured at a windowed frame rate of 2.2 kHz with the ESO NGC controller.
Ground-based infrared observations are often limited by atmospheric absorption and emission. Space-based instruments avoid this, but introduce unique technical challenges. We present the design of a flexible, compact, and cost-effective detector controller for space, based on commercial off-the-shelf components. Its architecture provides up to 50 configurable clock sequences and 16 biases, 32 16-bit video channels and several genera lpurpose ports. This allows for full control of CMOS detectors including Leonardo ‘SAPHIRA’ avalanche photodiode arrays (APD) which represent current state of the art in low-noise infrared imaging.
We present an update on the overall construction progress of the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT), 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, and some detailed end-to-end science simulations that have been effected to evaluate the final on-sky performance after data processing. 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 has experienced some delays in procurement and now has first light expected for the middle of 2019.
We present a summary of the cryogenic detector preamplifier development programme under way at the ANU. Cryogenic preamplifiers have been demonstrated for both near-infrared detectors (Teledyne H1RG and Leonardo SAPHIRA eAPD as part of development for the GMTIFS instrument) and optical CCDs (e2v CCD231-84 for use with the AAT/Veloce spectrograph). This approach to detector signal conditioning allows low-noise instrument amplifiers to be placed very close to an infra-red detector or optical CCD, isolating the readout path from external interference noise sources. Laboratory results demonstrate effective isolation of the readout path from external interference noise sources. Recent progress has focussed on the first on-sky deployment of four cryogenic preamp channels for the Veloce Rosso precision radial velocity spectrograph. We also outline future evolution of the current design, allowing higher speeds and further enhanced performance for the demanding applications required for the on instrument wavefront sensor on the Giant Magellan Integral Field Spectrograph (GMTIFS).
The Australian National University (ANU), we are undertaking to deploy a Lucky Imaging instrument on the 2.3 m telescope at Siding Springs using a Leonardo SAPHIRA near-infrared electron Avalanche Photo-Diode (eAPD) array, capable of high cadence imaging with frame rates of 10 - 5,000 Hz over the wavelength range of 0.8 μm to 2.5 μm. compact cryocooler capable of cooling the Leonardo SAPHRA APD and associated cryogenic electronics to temperatures below 100K with little to no vibration. An ideal candidate cryocooler is the Sunpower Cryotel GT with active vibration cancellation. The Cryotel GT is an orientation independent, Stirlng cycle cooler with water jacket heat rejection. This cooler will meet the system cooling requirements. The cryocooler has been integrated with the APD Lucky Imager cryostat through 3 rubber isolating mounts and bellows and tested while suspended from a stable frame. The tethers supporting the cryostat and cooler assembly are not attached to the cryostat and cooler. The exported vibration was measured simultaneously in all 3 axis on the external cryostat wall and internally on the cryostat getter attached directly to the cold tip of the cooler. The test results were collected while the cryocooler was cooling and at the stable set point, at various levels of cooling power and with thermal control enabled and disabled.
The GMTIFS instrument requires multiple rotary mechanisms that will operate in a cryogenic environment. Angular precision up to one arc-second is required without the use of IR sources as part of an encoder. A general design that uses an annular conical rim bearing supported by three pairs of tapered pinch rollers has been proposed. One pair of pinch rollers is mounted on a flexure hinge to provide preload and accommodate thermal expansion. A pair of off set cylindrical cams carried by the rotor, and four capacitive distance sensors fixed to the stator are utilized to implement a resolver. This provides a measure of the rotor orientation that is insensitive to runout of the rotor. A prototype of this design was constructed and tested in the lab to investigate the effect of runout in the tapered rollers and assess the performance of the rim bearing and various resolver designs. We present the results of this testing.
We present novel methods for mounting lenses in a pair of instruments that presented challenging optical and mechanical requirements. The first instrument is the replacement Natural Guide Star Sensor (NGS2) for CANOPUS at Gemini South, which incorporates an objective consisting of a stack of six lenses mounted in a common bore. A compliant radial spacer was used to eliminate lens decentre resulting from the additional radial clearance required to accommodate differential thermal strains between the low thermal expansion lenses and a common bore. In the same instrument, tangent contact toroidal spacers were deployed in place of traditional conical spacers to further reduce contact stresses in fragile calcium fluoride lens elements. The toroidal faces were specified with a 10μm profile tolerance to avoid possible edge contact between the spacers and lenses. We investigated milling and turning machining processes for the production of the spacers by comparing their results via Coordinate Measuring Machine (CMM) measurements. In the second instrument, Veloce, built for the Anglo-Australian Telescope, a lens decentre requirement of 40μm led us to develop a simple means of in-situ centring adjustment of the cell mounted lens. Physical testing of the finished instruments verified the performance of each of these methods. NGS2 produced images at the factory acceptance test in which 94% of encircled energy was captured by a single 16um detector pixel, surpassing the specification of 80%. Bench testing of Veloce during assembly showed that the adjustment mechanism allowed centring of the lens over a range of +/- 0.1mm with a precision of 5μm.
Veloce is an ultra-stabilized Echelle spectrograph for precision radial velocity measurements of stars. In order to maximize the grating performance, the air temperature as well as the air pressure surrounding it must be maintained within tight tolerances. The control goal was set at +/-10 mK and +/-1 mbar for air temperature and pressure respectively. The strategy developed by the design team resulted in separate approaches for each of the two requirements. A constrained budget early in the concept phase quickly ruled out building a large vacuum vessel to achieve stable air pressure. Instead, a simplified approach making use of a slightly over pressurized enclosure containing the whole spectrograph was selected in conjunction with a commercially available pressure controller. The temperature stability of Veloce is maintained through a custom array of PID controlled heaters placed on the outer skin of the internal spectrograph enclosure. This enclosure is also fully lined with 19 mm thick insulating panels to minimize the thermal fluctuations. A second insulated enclosure, built around the internal one, adds a layer of conditioned air to further shield Veloce from the ambient thermal changes. Early success of the environment control system has already been demonstrated in the integration laboratory, achieving results that amply exceed the goals set forth. Results presented show the long term stability of operation under varying barometric conditions. This paper details the various challenges encountered during the implementation of the stated designs, with an emphasis on the control strategy and the mechanical constraints to implement the solutions.
In this paper we present the Australian Astronomical Observatory’s concept design for Sphinx - a fiber positioner with 4,332 “spines” on a 7.77mm pitch for CFHT’s Mauna Kea Spectroscopic Explorer (MSE) Telescope. Based on the Echidna technology used with FMOS (on Subaru) and 4MOST (on VISTA), the next evolution of the tilting spine design delivers improved performance and superior allocation efficiency. Several prototypes have been constructed that demonstrate the suitability of the new design for MSE. Results of prototype testing are presented, along with an analysis of the impact of tilting spines on the overall survey efficiency. The Sphinx fiber positioner utilizes a novel metrology system for spine position feedback. The metrology design and the careful considerations required to achieve reliable, high accuracy measurements of all fibers in a realistic telescope environment are also presented.
Veloce is an ultra-stable fibre-fed R4 echelle spectrograph for the 3.9 m Anglo-Australian Telescope. The first channel to be commissioned, Veloce ‘Rosso’, utilises multiple low-cost design innovations to obtain Doppler velocities for sun-like and M-dwarf stars at <1 ms -1 precision. The spectrograph has an asymmetric white-pupil format with a 100-mm beam diameter, delivering R>75,000 spectra over a 580-930 nm range for the Rosso channel. Simultaneous calibration is provided by a single-mode pulsed laser frequency comb in tandem with a traditional arc lamp. A bundle of 19 object fibres ensures full sampling of stellar targets from the AAT site. Veloce is housed in dual environmental enclosures that maintain positive air pressure at a stability of ±0.3 mbar, with a thermal stability of ±0.01 K on the optical bench. We present a technical overview and early performance data from Australia's next major spectroscopic machine.
WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) on La Palma in the Canary Islands, Spain. It is a multi-object "pick-and-place" fibre-fed spectrograph with a 1000 fibre multiplex behind a new dedicated 2° prime focus corrector. The WEAVE positioner concept uses two robots working in tandem in order to reconfigure a fully populated field within the expected 1 hour dwell-time for the instrument (a good match between the required exposure times and the limit of validity for a given configuration due to the effects of differential refraction). In this paper we describe some of the final design decisions arising from the prototyping phase of the instrument design and provide an update on the current manufacturing status of the fibre positioner system.
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 Australian Astronomical Observatory's 'tilting spine' fibre positioning technology has been redeveloped to provide superior performance in a smaller package. The new design offers demonstrated closed-loop positioning errors of <2.8 μm RMS in only five moves (~10 s excluding metrology overheads) and an improved capacity for open-loop tracking during observations. Tilt-induced throughput losses have been halved by lengthening spines while maintaining excellent accuracy. New low-voltage multilayer piezo actuator technology has reduced a spine's peak drive amplitude from ~150V to <10V, simplifying the control electronics design, reducing the system's overall size, and improving modularity. Every spine is now a truly independent unit with a dedicated drive circuit and no restrictions on the timing or direction of fibre motion.
Starbugs are miniature piezoelectric ‘walking’ robots that can be operated in parallel to position many payloads (e.g.
optical fibres) across a telescope’s focal plane. They consist of two concentric piezo-ceramic tubes that walk with micron
step size. In addition to individual optical fibres, Starbugs have moved a payload of 0.75kg at several millimetres per
second. The Australian Astronomical Observatory previously developed prototype devices and tested them in the
laboratory. Now we are optimising the Starbug design for production and deployment in the TAIPAN instrument, which
will be capable of configuring 300 optical fibres over a six degree field-of-view on the UK Schmidt Telescope within a
few minutes. The TAIPAN instrument will demonstrate the technology and capability for MANIFEST (Many Instrument
Fibre-System) proposed for the Giant Magellan Telescope. Design is addressing: connector density and voltage
limitations, mechanical reliability and construction repeatability, field plate residues and scratching, metrology stability,
and facilitation of improved motion in all aspects of the design for later evaluation. Here we present the new design
features of the AAO TAIPAN Starbug.
We report here on the software Hack Day organised at the 2014 SPIE conference on Astronomical Telescopes and Instrumentation in Montréal. The first ever Hack Day to take place at an SPIE event, the aim of the day was to bring together developers to collaborate on innovative solutions to problems of their choice. Such events have proliferated in the technology community, providing opportunities to showcase, share and learn skills. In academic environments, these events are often also instrumental in building community beyond the limits of national borders, institutions and projects. We show examples of projects the participants worked on, and provide some lessons learned for future events.
The Australian Astronomical Observatory has extensively prototyped a new robotic positioner to allow simultaneous
positioning of optical fibers at the focal plane called ‘Starbugs’. The Starbug devices each consist of two concentric
piezoelectric tubes that ‘walk’ the optical fiber over the focal plane to accuracy of several microns. Ongoing research has
led to the development of several Starbug prototypes, but lack of performance data has hampered further progress in the
design of the Starbug positioners and the support equipment required to power and control them. Furthermore, Starbugs
have been selected for the TAIPAN instrument, a prototype for MANIFEST on the GMT. A need now arises to measure
and characterize 100’s of piezoelectric tubes before full scale production of Starbugs for TAIPAN. The manual
measurements of these piezoelectric tubes are a time consuming process taking several hours. Therefore, a versatile
automated system is needed to measure and characterize these tubes in the laboratory before production of Starbugs. We
have solved this problem with the design of an automated LabVIEW application that significantly reduces test times to
several minutes. We present the various design aspects of the automation system and provide analyses of example
piezoelectric tubes for Starbugs.
MANIFEST is a fibre feed system for the Giant Magellan Telescope that, coupled to the seeing-limited instruments
GMACS and G-CLEF, offers qualitative and quantitative gains over each instrument’s native capabilities in terms of
multiplex, field of view, and resolution. The MANIFEST instrument concept is based on a system of semi-autonomous
probes called “Starbugs” that hold and position hundreds of optical fibre IFUs under a glass field plate placed at the
GMT Cassegrain focal plane. The Starbug probes feature co-axial piezoceramic tubes that, via the application of
appropriate AC waveforms, contract or bend, providing a discrete stepping motion. Simultaneous positioning of all
Starbugs is achieved via a closed-loop metrology system.
We present advances in the patented Echidna 'tilting spine' fiber positioner technology that has been in operation since 2007 on the SUBARU telescope in the FMOS system. The new Echidna technology is proposed to be implemented on two large fiber surveys: the Dark Energy Spectroscopic Instrument (DESI) (5000 fibers) as well the Australian ESO Positioner (AESOP) for 4MOST, a spectroscopic survey instrument for the VISTA telescope (~2500 fibers). The new 'superspine' actuators are stiffer, longer and more accurate than their predecessors. They have been prototyped at AAO, demonstrating reconfiguration times of ~15s for errors of <5 microns RMS. Laboratory testing of the prortotype shows accurate operation at temperatures of -10 to +30C, with an average heat output of 200 microwatts per actuator during reconfiguration. Throughput comparisons to other positioner types are presented, and we find that losses due to tilt will in general be outweighed by increased allocation yield and reduced fiber stress FRD. The losses from spine tilt are compensated by the gain in allocation yield coming from the greater patrol area, and quantified elsewhere in these proceedings. For typical tilts, f-ratios and collimator overspeeds, Echidna offers a clear efficiency gain versus current r-that or theta-phi positioners.
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 ~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; ~1600 fibres go to two spectrographs with resolution R<5000 (λ~390-930 nm) and
~800 fibres to a spectrograph with R>18,000 (λ~392-437 nm and 515-572 nm and 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].
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.
WEAVE is the next-generation wide-field optical spectroscopy facility for the William Herschel Telescope (WHT) in
La Palma, Canary Islands, Spain. It is a multi-object "pick and place" fibre fed spectrograph with more than one
thousand fibres behind a new dedicated 2° prime focus corrector, This is similar in concept to the Australian
Astronomical Observatory's 2dF instrument1 with two observing plates, one of which is observing the sky while other
is being reconfigured by a robotic fibre positioner. It will be capable of acquiring more than 10000 star or galaxy
spectra a night.
The WEAVE positioner concept uses two robots working in tandem in order to reconfigure a fully populated field
within the expected 1 hour dwell-time for the instrument (a good match between the required exposure times and the
limit of validity for a given configuration due to the effects of differential refraction).
TAIPAN is a spectroscopic instrument designed for the UK Schmidt Telescope at the Australian Astronomical Observatory. In addition to undertaking the TAIPAN survey, it will serve as a prototype for the MANIFEST fibre positioner system for the future Giant Magellan Telescope. The design for TAIPAN incorporates up to 300 optical fibres situated within independently-controlled robotic positioners known as Starbugs, allowing precise parallel positioning of every fibre, thus significantly reducing instrument configuration time and increasing observing time. We describe the design of the TAIPAN instrument system, as well as the science that will be accomplished by the TAIPAN survey. We also highlight results from the on-sky tests performed in May 2014 with Starbugs on the UK Schmidt Telescope and briefly introduce the role that Starbugs will play in MANIFEST.
We present a concept for a 4000-fibre positioner for DESpec, based on the Echidna ‘tilting spine’ technology. The DESpec focal plane is 450mm across and curved, and the required pitch is ~6.75mm. The size, number of fibers and curvature are all comparable with various concept studies for similar instruments already undertaken at the AAO, but present new challenges in combination. A simple, low-cost, and highly modular design is presented, consisting of identical modules populated by identical spines. No show-stopping issues in accommodating either the curvature or the smaller pitch have been identified, and the actuators consist largely of off-the-shelf components. The actuators have been prototyped at AAO, and allow reconfiguration times of ~15s to reach position errors 7 microns or less. Straightforward designs for metrology, acquisition, and guiding are also proposed. The throughput losses of the entire positioner system are estimated to be ~15%, of which 6.3% is attributable to the tilting-spine technology.
First light from the SAMI (Sydney-AAO Multi-object IFS) instrument at the Anglo-Australian Telescope (AAT) has
recently proven the viability of fibre hexabundles for multi-IFU spectroscopy. SAMI, which comprises 13 hexabundle
IFUs deployable over a 1 degree field-of-view, has recently begun science observations, and will target a survey of
several thousand galaxies. The scientific outputs from such galaxy surveys are strongly linked to survey size, leading the
push towards instruments with higher multiplex capability. We have begun work on a new instrument concept, called
Hector, which will target a spatially-resolved spectroscopic survey of up to one hundred thousand galaxies. The key
science questions for this instrument concept include how do galaxies get their gas, how is star formation and nuclear
activity affected by environment, what is the role of feedback, and what processes can be linked to galaxy groups and
clusters. One design option for Hector uses the existing 2 degree field-of view top end at the AAT, with 50 individual
robotically deployable 61-core hexabundle IFUs, and 3 fixed format spectrographs covering the visible wavelength range
with a spectral resolution of approximately 4000. A more ambitious option incorporates a modified top end at the AAT
with a new 3 degree field-of-view wide-field-corrector and 100 hexabundle IFUs feeding 6 spectrographs.
The Australian Astronomical Observatory (AAO) has recently completed a feasibility study for a fiber-positioner facility proposed for the Giant Magellan Telescope (GMT), called MANIFEST (the Many Instrument Fiber System). The MANIFEST instrument takes full advantage of the wide-field focal plane to efficiently feed other instruments. About 2000 individually deployable fiber units are envisaged, with a wide variety of aperture types (single-aperture, image- or pupil-slicing, IFU). MANIFEST allows (a) full use of the GMT's 20' field-of-view, (b) a multiplexed IFU capability, (c) greatly increased spectral resolution via image-slicing, (d) the possibility of OH-suppression in the near-infrared.
Starbugs are miniature piezoelectric 'walking' robots with the ability to simultaneously position many optical fibres
across a telescope's focal plane. Their simple design incorporates two piezoceramic tubes to form a pair of concentric
'legs' capable of taking individual steps of a few microns, yet with the capacity to move a payload several millimetres
per second. The Australian Astronomical Observatory has developed this technology to enable fast and accurate field
reconfigurations without the inherent limitations of more traditional positioning techniques, such as the 'pick and place'
robotic arm. We report on our recent successes in demonstrating Starbug technology, driven principally by R&D efforts
for the planned MANIFEST (many instrument fibre-system) facility for the Giant Magellan Telescope. Significant
performance gains have resulted from improvements to the Starbug system, including i) the use of a vacuum to attach
Starbugs to the underside of a transparent field plate, ii) optimisation of the control electronics, iii) a simplified
mechanical design with high sensitivity piezo actuators, and iv) the construction of a dedicated laboratory 'test rig'. A
method of reliably rotating Starbugs in steps of several arcminutes has also been devised, which integrates with the pre-existing
x-y movement directions and offers greater flexibility while positioning. We present measured performance data
from a prototype system of 10 Starbugs under full (closed-loop) control, at field plate angles of 0-90 degrees.
Following the successful commissioning of SAMI (Sydney-AAO Multi-object IFU) the AAO has undertaken concept
studies leading to a design of a new instrument for the AAT (Hector). It will use an automated robotic system for the
deployment of fibre hexabundles to the focal plane. We have analysed several concepts, which could be applied in the
design of new instruments or as a retrofit to existing positioning systems. We look at derivatives of Starbugs that could
handle a large fibre bundle as well as modifications to pick and place robots like 2dF or OzPoz. One concept uses large
magnetic buttons that adhere to a steel field plate with substantial force. To move them we replace the gripper with a
pneumatic device, which engages with the button and injects it with compressed air, thus forming a magnet preloaded air
bearing allowing virtually friction-less repositioning of the button by a gantry or an R-Theta robot. New fibre protection,
guiding and retraction systems are also described. These developments could open a practical avenue for the upgrade to a
number of instruments.
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.
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