The Telescopio Nazionale Galileo (TNG) hosts, starting in April 2012, the visible spectrograph HARPS-N. It is based
on the design of its predecessor working at ESO's 3.6m telescope, achieving unprecedented results on radial velocity
measurements of extrasolar planetary systems. The spectrograph's ultra-stable environment, in a temperature-controlled
vacuum chamber, will allow measurements under 1 m/s which will enable the characterization of rocky, Earth-like
planets. Enhancements from the original HARPS include better scrambling using octagonal section fibers with a shorter
length, as well as a native tip-tilt system to increase image sharpness, and an integrated pipeline providing a complete set
Observations in the Kepler field will be the main goal of HARPS-N, and a substantial fraction of TNG observing time
will be devoted to this follow-up. The operation process of the observatory has been updated, from scheduling
constraints to telescope control system. Here we describe the entire instrument, along with the results from the first
The European Space Agency, in the framework of its Space Situational Awareness (SSA) Preparatory Programme, has
commissioned a study for a global network of surveillance telescopes to monitor the ever increasing number of objects in
Earth orbit. A possible scenario identified by the study is a network of 20 SSA Telescopes located at various observatory
sites. This paper presents the conceptual design of a telescope system optimised for wide field, short exposures and fast
tracking – all requirements of SSA.
The requirements of the SSA telescope will be presented followed by a brief review of potential telescope technologies.
Following a trade study analysis a 1 m compact Schmidt telescope design was chosen. This design provides a field of
view of 3.4 degrees diameter. The design is achromatic and covers the wavelength range 380 – 900 nm. The sensitivity
of the telescope is such that it can monitor the orbital parameters of objects as small as 1 cm in low Earth orbit. This is
equivalent to 17<sup>th</sup> magnitude in 0.07 seconds at a signal to noise ratio of 5. The telescope is mounted on an Altitude-
Azimuth type mount that enables wide coverage of the sky and fast tracking speeds. The entire telescope is contained
within a Calotte type enclosure. The camera, detector control, and telescope control system design will also be presented.
Systems engineering aspects will be addressed, with particular attention given to the analysis and flow-down of
requirements and a practical and pragmatic process of system-level design trade-offs.
CANARY is an on-sky demonstrator adaptive optics (AO) system that in 2010 provided the first on-sky demonstration
of open-loop tomographic adaptive optics correction using natural guide stars (NGS). Phase B of the CANARY
experiment aims to extend the instrument from its original configuration by also measuring wavefronts from four offaxis
Rayleigh laser guide stars (LGS). This upgrade allows CANARY to perform tomographic wavefront sensing over a
2.5arcminute field of view using any mix of up to seven off-axis wavefront sensors (four LGS and three NGS)
simultaneously. AO correction within CANARY is performed on-axis along a single line of sight using a 52-actuator
deformable mirror being controlled in open-loop. Here we give an overview of the Phase B LGS system, discuss the
calibration of a mixed NGS/LGS tomographic system and present the recent laboratory and on-sky results from the
Phase B commissioning.
The VISTA Telescope<sup>1</sup> is obtaining superb survey images. The M1 support system is essential to image quality and uses
astatic pneumatic supports to balance the M1 against the varying effects of gravity and wind, with four axes being
actively controlled via software and CANbus. The system also applies externally determined active optics force patterns.
The mechanical, electronic, software and control design and as-built operation of the system are described, with the
practical design points discussed.
The CANARY on-sky MOAO demonstrator is being integrated in the laboratory and a status update about its
various components is presented here. We also discuss the alignment and calibration procedures used to improve
system performance and overall stability. CANARY will be commissioned at the William Herschel Telescope at
the end of September 2010.
The most challenging of the metrology needs of multi-objects instruments is the registration of the pupil on the
deformable mirror which corrects the wavefront errors. Pick-off mirrors in multi-objects instruments and specially
spectrographs (MOS) require accurate positioning and simultaneous viewing of the pupil on the deformable mirror
(DM) and the focal plane image on the image slicer at the sub-micron level. A laboratory test prototype simulating the
telescope (E-ELT), the beam steering mirror (BSM) and the pupil imaging mirror (PIM), is presented to confirm the
correct positioning of the pupil on the DM and to provide the movements of the moveable optical elements to achieve it.
The opto-mechanical design and testing of this prototype is shown. The BSM stages (Goniometric cradle, Rotation, &
Linear) provide the key mechanical system elements, with precision alignment, resolution, and repeatability .
The design and behaviour of the control system is discussed; the ultimate aim of which is to adjust the BSM and PIM to
correct for any slight mis-positioning of the pick-off mirror and any temporal drift of all the components to achieve the
required alignment. The control system can also cope with flexure effects when required.
The ISS (Integral-field Spectrograph System) has been designed as part of the EAGLE Phase A Instrument Study for the
E-ELT. It consists of two input channels of 1.65x1.65 arcsec field-of-view, each reconfigured spatially by an imageslicing
integral-field unit to feed a single near-IR spectrograph using cryogenic volume-phase-holographic gratings to
disperse the image spectrally. A 4k x 4k array detector array records the dispersed images. The optical design employs
anamorphic magnification, image slicing, VPH gratings scanned with a novel cryo-mechanism and a three-lens camera.
The mechanical implementation features IFU optics in Zerodur, a modular bench structure and a number of highprecision
VISTA is a survey telescope which will deliver 0.5 arc second images over a 2 degree diameter unvignetted field of view. The Telescope Work Package which includes both the Mount and M1 support system is being designed and built by VertexRSI. The Contract includes an extensive factory test programme after full assembly of the telescope systems. The main optical elements in projects this size are ordered early so that they are ready for integration with the telescope on site. This means that testing of the telescope with its optics in the factory environment is rarely possible. So to try and avoid problems during site integration, the scope and extent of hardware and control system factory testing is significant and should be suitably in-depth. This paper describes the metrology and testing carried out to date in the factory environment. In addition the axis control system was simulated using Matlab-Simulink models. The models were also used as the basis of software verification using hardware-in-the-loop tests in a model-based development process. This development process and subsequent factory testing is described in some detail, and covers the mount axes and the M1 support system. In conclusion this paper discusses the perceived usefulness of the extent of the factory testing employed and how this is expected to mesh with the process of telescope and optics integration on site.
The integration of the SPIRE BSM hardware and its controlling software used the hardware-in-the-loop dSPACE system to enable fast development of the control system and separate site development of the hardware and software. After this separate development, integration of the prototypes at one of the sites was completely successful. Similar development of the SMECm hardware is also described.
The Beam Steering Mirror (BSM) subsystem is a critical part of the SPIRE Instrument for the ESA Herschel Space Observatory. It is used to steer the beam of the telescope on the photometer and spectrometer arrays in 2 orthogonal directions, for purposes of fully sampling the image, fine pointing and signal modulation.
The UK Astronomy Technology Centre (ATC) is part of a consortium of 15 institutes in Europe and the USA which was formed to build SPIRE and which is lead by Dr M. Griffin of the University of Wales, Cardiff.
Systems Engineering has been used throughout the development of the Visible and Infrared Survey Telescope for Astronomy (VISTA). VISTA was originally conceived as being a classic 4m telescope with wide-field imaging capability. The UK Astronomy Technology Centre (UK ATC) radically changed this thinking by treating the whole design as one system, integrating the camera optics into the telescope design.
To maximise the performance, an f/1 primary mirror was adopted resulting in a very compact telescope and enclosure. Amongst other benefits, this reduced the overall mass of the telescope from 250 to 90 tonnes. During this optimisation process, the concept of a direct imaging K-short camera was developed. This development, in conjunction with an increase in IR field of view, produced a system with uniform image quality and throughput across a 350 mm diameter focal plane, 1.65 degree field.
While this has presented some major engineering challenges, the approach has produced a system which is both scientifically rewarding and achievable. The optimisation, design trade-offs and Technical Specification developed in the conceptual design phase were achieved through a systems analysis approach.
This paper describes some of the key systems engineering decisions and the tools employed to achieve them. Current systems engineering activities are described and future plans outlined.
The design of VISTA (Visible and Infrared Survey Telescope for Astronomy) requires close interaction between the science requirements, the optical and active mechanical design of the telescope and its instrumentation with the wavefront sensing. The optical design is based on an integrated approach of the telescope with tow separate cameras, one working in the IR waveband and the other working in the Visible waveband. The large field of view (2 degrees in the visible and 1.65 degrees in the IR), the seeing-limited resolution required (FWHM of 0.4 arcsec for the visible and 0.5 arcsec for the IR), the technological advance in active telescopes and large IR arrays and the f/1 quasi Ritchey-Chretien telescope design, makes this telescope a very powerful tool in performing high resolution and large astronomical surveys. A system analysis, modeling the various sources of errors such as optical aberrations, surface errors, control errors, environmental effects and detector effects is presented in this paper.