We present Mookodi (meaning “rainbow” in Sesotho), a multipurpose instrument with a low-resolution spectrograph mode and a multi-filter imaging mode for quick-reaction astronomical observations. The instrument, mounted on the 1-m Lesedi telescope at the South African Astronomical Observatory in Sutherland (South Africa), is based on the low-resolution spectrograph for the rapid acquisition of transients (SPRAT) instrument in operation on the 2-m Liverpool Telescope in La Palma (Canary Islands, Spain). Similar to SPRAT, Mookodi has a resolution R≈350 and an operating wavelength range in the visible (∼4000 to 8000 Å). The linear optical design, as in SPRAT, is made possible through the combination of a volume phase holographic transmission grating as the dispersive element and a prism pair (grism), which makes it possible to rapidly and seamlessly switch to an imaging mode by pneumatically removing the slit and grism from the beam and using the same detector as in spectrographic mode to image the sky. This imaging mode is used for auto-target acquisition, but the inclusion of filter slides in Mookodi’s design also provides the capability to perform imaging with a field-of-view ≈10′×10′ (∼0.6″/px) in the complete Sloan Digital Sky Survey filter set.
We present an update on the overall integration progress of the WEAVE next-generation spectroscopy facility for the William Herschel Telescope (WHT), now scheduled for first light in early-2021, with almost all components now arrived at the observatory. 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 implemented 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 mini 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.
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.
WEAVE is the new multi-object spectrograph for the William Herschel Telescope on La Palma. The culmination of prime focus, the large number of fibers and the wide resolution range has required a stringent optical design, which in turn demands a spectrograph with tight positional tolerances and large final focal plane. To capture this focal plane each of the two cryostats has two e2v 6k × 6k CCDs mounted as a mosaic. As well as being cooled to 150K via liquid nitrogen, the positional tolerances for the sensitive areas are flatness 60μm p-v over the entire image area, rotation around X and Y axis ±50 arcmin, translation in X, Y and Z ± 50 micron. We have used a Stil confocal measuring head mounted on two Thorlab translation stages to create a X,Y mount, controlled by a Raspberry Pi that is capable of recording measurements in Z to better than 1μm accuracy. This is used to measure the flatness and deformation of the image area under vacuum, and when cooled to 150K and the overall tip and tilt of the image plane to ensure they meet specification and are repeatable. In addition to this measuring system, we use a Thorlabs CMOS camera with a Navitar 50mm lens to ensure each CCDs image area is within specification with regards X and Y translation. In order to satisfy the above requirements, we designed the CCD mount to be adjustable (on initial setup), correctly constrained, isolated from liquid nitrogen boil-off vibration, and thermally insulating.
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 Liverpool Telescope is a fully robotic 2-metre telescope located at the Observatorio del Roque de los Muchachos on the Canary Island of La Palma. The telescope began routine science operations in 2004, and currently seven simultaneously mounted instruments support a broad science programme, with a focus on transient followup and other time domain topics well suited to the characteristics of robotic observing. Work has begun on a successor facility with the working title ‘Liverpool Telescope 2’. We are entering a new era of time domain astronomy with new discovery facilities across the electromagnetic spectrum, and the next generation of optical survey facilities such as LSST are set to revolutionise the field of transient science in particular. The fully robotic Liverpool Telescope 2 will have a 4-metre aperture and an improved response time, and will be designed to meet the challenges of this new era. Following a conceptual design phase, we are about to begin the detailed design which will lead towards the start of construction in 2018, for first light ∼2022. In this paper we provide an overview of the facility and an update on progress.
IO:I is a new instrument that has recently been commissioned for the Liverpool Telescope, extending current imaging capabilities beyond the optical and into the near-infrared. Cost has been minimized by the use of a previously decommissioned instrument’s cryostat as the base for a prototype and retrofitting it with Teledyne’s 1.7-μm cutoff Hawaii-2RG HgCdTe detector, SIDECAR ASIC controller, and JADE2 interface card. The mechanical, electronic, and cryogenic aspects of the cryostat retrofitting process will be reviewed together with a description of the software/hardware setup. This is followed by a discussion of the results derived from characterization tests, including measurements of read noise, conversion gain, full well depth, and linearity. The paper closes with a brief overview of the autonomous data reduction process and the presentation of results from photometric testing conducted on on-sky, pipeline processed data.
We describe the development of a low cost, low resolution (R ~ 350), high throughput, long slit spectrograph covering visible (4000-8000) wavelengths. The spectrograph has been developed for fully robotic operation with
the Liverpool Telescope (La Palma). The primary aim is to provide rapid spectral classification of faint (V ∼ 20)
transient objects detected by projects such as Gaia, iPTF (intermediate Palomar Transient Factory), LOFAR,
and a variety of high energy satellites. The design employs a volume phase holographic (VPH) transmission grating as the dispersive element combined with a prism pair (grism) in a linear optical path. One of two peak spectral sensitivities are selectable by rotating the grism. The VPH and prism combination and entrance slit are deployable, and when removed from the beam allow the collimator/camera pair to re-image the target field onto the detector. This mode of operation provides automatic acquisition of the target onto the slit prior to spectrographic observation through World Coordinate System fitting. The selection and characterisation of optical components to maximise photon throughput is described together with performance predictions.
Some modern CCD designs provide a dummy readout amplifier that is designed to be operated with the same clock and bias signals as the true amplifier in order to provide a measurement of clock induced and other common-mode noise signals in the true amplifier readout. In general the dummy output signal is subtracted electronically from the true output signal in a differential input preamplifier before digitization. Here we report on an alternative approach where both signals are digitized and the subtraction done in software. We present the results of testing this method of operation using the ARC SDSU generation III CCD controllers and an e2v CCD231 device and find it works well, allowing a noise figure of ~ 2:2 electrons to be reached in the presence of significantly higher (~ 6 electrons) pickup noise. In addition we test the effectiveness of using unused (but still genuine) readout amplifiers on the detector to provide a pseudo-dummy output, which we also find effective in cancelling common mode noise. This provides the option of implementing noise reduction on CCDs that are not equipped with dummy outputs at the expense of overall readout speed.
IO:I is a new instrument in development for the Liverpool Telescope, extending current imaging capabilities beyond the optical and into the near infrared. Cost has been minimised by use of a previously decommissioned instrument’s dewar as the base for a prototype, and retrofitting it with a 1.7μm cutoff Hawaii-2RG HgCdTe detector, SIDECAR ASIC controller and JADE2 interface card. Development of this prototype is nearing completion and will be operational mid 2014. In this paper, the mechanical, electronic and cryogenic facets of the dewar retrofitting process will be discussed together with a description of the instrument control system software/hardware setup. Finally, a brief overview of some initial testing undertaken on the engineering grade array will be given, along with future commissioning plans for the instrument.
We present an overview of and status report on the WEAVE next-generation spectroscopy facility for the William
Herschel Telescope (WHT). WEAVE principally targets optical ground-based follow up of upcoming ground-based
(LOFAR) and space-based (Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2-degree
prime focus field of view at the WHT, with a buffered pick-and-place positioner system hosting 1000 multi-object
(MOS) fibres, 20 integral field units, or a single large IFU for each observation. The fibres are fed to a single
spectrograph, with a pair of 8k(spectral) x 6k (spatial) pixel cameras, located within the WHT GHRIL enclosure on the
telescope Nasmyth platform, supporting observations at R~5000 over the full 370-1000nm wavelength range in a single
exposure, or a high resolution mode with limited coverage in each arm at R~20000. The project is now in the final
design and early procurement phase, with commissioning at the telescope expected in 2017.
We present the preliminary design of the WEAVE next generation spectroscopy facility for the William Herschel
Telescope (WHT), principally targeting optical ground-based follow up of upcoming ground-based (LOFAR) and spacebased
(Gaia) surveys. WEAVE is a multi-object and multi-IFU facility utilizing a new 2 degree prime focus field of view
at the WHT, with a buffered pick and place positioner system hosting 1000 multi-object (MOS) fibres or up to 30
integral field units for each observation. The fibres are fed to a single spectrograph, with a pair of 8k(spectral) x 6k
(spatial) pixel cameras, located within the WHT GHRIL enclosure on the telescope Nasmyth platform, supporting
observations at R~5000 over the full 370-1000nm wavelength range in a single exposure, or a high resolution mode with
limited coverage in each arm at R~20000.
GRB jets contain rapidly moving electrons which will spiral around magnetic field lines. This causes them to
emit polarized synchrotron emission. We have built a series of polarimeters (RINGO and RINGO2) to investigate
this by measuring the polarization of optical light from GRBs at a certain single wavelength. The instruments
are mounted on the Liverpool Telescope, which is a fully robotic (i.e. unmanned) telescope on La Palma which
reacts to triggers from satellites such as the NASA SWIFT mission. This has had great success, with the first
ever detections of early time optical polarization being made. In addition, the first measurements of the change
in optical polarization from a GRB as the jet expands have recently been obtained.
In this paper we describe the design and construction of RINGO3. This will be a multi-colour instrument
that can observe simultaneously at three wavelengths. By doing so we will be able to unambiguously identify
where in the burst the polarized emission is coming from. This will allow us to distinguish between three
possibilities: (1) Magnetic instabilities generated in the shock front, (2) Line of sight effects and (3) Large-scale
magnetic fields present throughout the relativistic outflow. The instrument design combines a rapidly rotating
polaroid, specially designed polarization insensitive dichroic mirrors and three electron multiplying CCD cameras
to provide simultaneous wavelength coverage with a time resolution of 1 second.
We describe the design and construction of a new novel optical polarimeter (RINGO2) for the Liverpool Telescope.
The instrument is designed for rapid (< 3 minute) followup observations of Gamma Ray Bursts in order to
measure the early time polarization and time evolution on timescales of ~ 1 - 10000 seconds. By using a fast
rotating Polaroid whose rotation is synchronized to control the readout of an electron multiplying CCD eight
times per revolution, we can rebin our data in the time domain after acquisition with little noise penalty, thereby
allowing us to explore the polarization evolution of these rapidly variable objects for the first time.
By the precise timing of the low amplitude (0.005 - 0.02 magnitude) transits of exoplanets around their parent
star it should be possible to infer the presence of other planetary bodies in the system down to Earth-like
masses. We describe the design and construction of RISE, a fast-readout frame transfer camera for the Liverpool
Telescope designed to carry out this experiment. The results of our commissioning tests are described as well as
the data reduction procedure necessary. We present light curves of two objects, showing that the desired timing
and photometric accuracy can be obtained providing that autoguiding is used to keep the target on the same
detector pixel for the entire (typically 4 hour) observing run.
KEYWORDS: Telescopes, Web services, Java, Signal to noise ratio, Standards development, Astronomy, Robotics, Astronomical telescopes, Information security, Sun
Distributed, heterogenous networks of telescopes will require a very different approach to scheduling than classically operated single site instruments. We have previously discussed the advantages of an economic (free market) approach to this problem. In this paper we describe a test implementation of the technologies using a generic
toolkit designed to make negotiable and chargeable web services.
In the last few years the ubiquitous availability of high bandwidth networks has changed the way both robotic and non-robotic telescopes operate, with single isolated telescopes being integrated into expanding "smart" telescope networks that can span continents and respond to transient events in seconds. The Heterogeneous Telescope Networks (HTN)* Consortium represents a number of major research groups in the field of robotic telescopes, and together we are proposing a standards based approach to providing interoperability between the existing proprietary telescope networks. We further propose standards for interoperability, and integration with, the emerging Virtual Observatory.
We present the results of the first interoperability meeting held last year and discuss the protocol and transport standards agreed at the meeting, which deals with the complex issue of how to optimally schedule observations on geographically distributed resources. We discuss a free market approach to this scheduling problem, which must initially be based on ad-hoc agreements between the participants in the network, but which may eventually expand into a electronic market for the exchange of telescope time.
Linking ground based telescopes with astronomical satellites, and using the emerging field of intelligent agent architectures to provide crucial autonomous decision making in software, we have combined data archives and research class robotic telescopes along with distributed computing nodes to build an ad-hoc peer-to-peer heterogeneous network of resources. The eSTAR Project* uses intelligent agent technologies to carry out resource discovery, submit observation requests and analyze the reduced data returned from a meta-network of robotic telescopes. We present the current operations paradigm of the eSTAR network and describe the direction of in which the project intends to develop over the next several years. We also discuss the challenges facing the project, including the very real sociological one of user acceptance.
We describe the design and construction of a novel optical ring-polarimeter (RINGO) for the Liverpool Telescope. The instrument is designed for rapid (< 5 minutes) followup observations of Gamma Ray Bursts in order to measure the early time polarization and its evolution for the first time. Sensitivity calculations and data reduction procedures are described, and the results of on-sky commissioning presented. The instrument is now on the telescope and in routine use during GRB followup.
In this paper we discuss the requirements for producing instrumentation suitable for robotic use, on a fully automated telescope. The design compromises and simplifications needed to produce instruments that can be left unattended for long periods of operation are investigated. We describe how we structure the control system to provide fail-safe operation of the instruments.
The Liverpool Telescope is a 2.0 metre robotic telescope that is operating unattended at the Observatorio del Roque de Los Muchachos, Spain. This paper gives an overview of the design and implementation of the telescope and its instrumentation and presents a snapshot of the current performance during the commissioning process. Science observations are under way, and we give brief highlights from a number of programmes that have been enabled by the robotic nature of the telescope.
As distributed systems are becoming more and more diverse in application there is a growing need for more intelligent resource scheduling. eSTAR Is a geographically distributed network of Grid-enabled telescopes, using grid middleware to provide telescope users with an authentication and authorisation method, allowing secure, remote access to such resources. The eSTAR paradigm is based upon this secure, single sign-on, giving astronomers or their agent proxies direct access to these telescopes. This concept, however, involves the complex issue of how to schedule observations stored within physically distributed media, on geographically distributed resources. This matter is complicated further by the varying degrees of constraints placed upon observations such as timeliness, atmospheric and meteorological conditions, and sky brightness to name a few.
This paper discusses a free market approach to this scheduling problem, where astronomers are given credit, instead of time, from their respective TAGs to spend on telescopes as they see fit. This approach will ultimately provide a community-driven schedule, genuine indicators of the worth of specific telescope time and promote a more efficient use of that time, as well as demonstrating a 'survival of the fittest' type selection.
The eSTAR Project uses intelligent agent technologies to carry out resource discovery, submit observation requests and analyze the reduced data returned from a network of robotic telescopes in an observational grid. The agents are capable of data mining and cross-correlation tasks using on-line catalogues and databases and, if necessary, requesting additional data and follow-up observations from the telescopes on the network. We discuss how the maturing agent technologies can be used both to provide rapid followup to time critical events, and for long term monitoring of known sources, utilising the available resources in an intelligent manner.
KEYWORDS: Telescopes, Astronomy, Robotics, Databases, Astronomical telescopes, Space telescopes, Astrophysics, Prototyping, Control systems, Data archive systems
The e-STAR (e-Science Telescopes for Astronomical Research) project uses GRID techniques to develop the software infrastructure for a global network of robotic telescopes. The basic architecture is based around Intelligent Agents which request data from Discovery Nodes that may be telescopes or databases. Communication is based on a development of the XML RTML language secured using the Globus I/O library, with status serving provided via LDAP. We describe the system architecture and protocols devised to give a distributed approach to telescope scheduling, as well as giving details of the implementation of prototype Intelligent Agent and Discovery Node systems.
Five per-cent of the observing time on the Liverpool Telescope (a 2-m robotic telescope sited in La Palma) will be set aside for public understanding of science. Schools access will be via, a queue scheduling mechanism, and public access via live Planetarium shows. We describe the development and performance of a generic Java message passing system to allow communication between the processes implementing the robotic control of the telescope and the remote processes that will be run at the Planetarium. We also describe an adaptive data compression algorithm to allow transfer of data back from the telescope in near real time and our software for Planetarium access which allows staff at the Planetarium to implement their own control system and display software. Finally we describe our hierarchical web-based system for schools to input observation requests and the image processing software we have developed to allow them to make quantitative measurements of the resulting data.
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