Following the scientific requirements developed by a ESO Working Group on Multi Object Spectroscopy, we present a design concept for a facility suitable for massively-multiplexed optical spectroscopy. We propose a very wide-field Cassegrain telescope optimised for fibre-fed spectroscopy. Our design provides an optical and ADC-corrected field of 2.5 degree diameter for an 11.4m primary, with a three-element corrector and ADC. A gravity invariant focus for the central 10 arc-minute field can be inserted to host a giant IFU. The telescope has an exceptionally large etendue and provides adequate image quality in the 360- 1300 nm, or in the 1300-1800 nm wavelength range. The telescope is very compact enabling an economic enclosure. We stress the importance of developing simultaneously detailed designs for the telescope and instrumentation highlighting curved detectors as key elements to optimally exploit the telescope’s potential via fast spectroscopic cameras at low cost. With this concept, more than 15000 fibres can be positioned in the focal plane with existing technology enabling a revolution in spectroscopic discovery space and follow-up of panoramic imaging surveys including LSST.
Since the beginning of the development of the Gran Telescopio Canarias (GTC), an Adaptive Optics (AO) system was considered necessary to exploit the full diffraction-limited potential of the telescope. The GTC AO system designed during the last years is based on a single deformable mirror conjugated to the telescope pupil, and a Shack-Hartmann wavefront sensor with 20 x 20 subapertures, using an OCAM2 camera. The GTCAO system will provide a corrected beam with a Strehl Ratio (SR) of 0.65 in K-band with bright natural guide stars.
Most of the subsystems have been manufactured and delivered. The upgrade for the operation with a Laser Guide Star (LGS) system has been recently approved. The present status of the GTCAO system, currently in its laboratory integration phase, is summarized in this paper.
The European Solar Telescope, EST, (, ) is a 4-meter solar telescope to be built in the Canary Islands in the near future. In order to select the best configuration for the EST telescope facilities, thermal and CFD analyses have been carried out to evaluate the seeing degradation produced by the telescope environment. The aim of this study is to calculate the values of optical parameters in different configurations and to find out which one causes the lowest image quality degradation. Starting from the determination of seeing degradation along the optical path by CFD techniques, several configurations have been compared making it possible to decide the future development line for the EST.
The European Solar Telescope (EST) is a European collaborative project promoted by the European Association for Solar Telescopes (EAST) to build a high resolution 4m class solar telescope in the Canary Islands. Since 2008 to 2011 a Design Study has been developed to define the Conceptual Design of EST.
This paper presents a description of the conceptual design of EST and the results of the preliminary performance simulations, mainly focused to obtain the best telescope image quality.
A study is presented for the realization of the heat stop for the 4-m European Solar Telescope EST, whose
feasibility study will be completed in 2011. EST is an on-axis Gregorian telescope, equipped with a four-meter
diameter primary mirror and primary focal length of about six meters. The heat stop, positioned at the primary
focus, must be able to remove a heat load of 13 kW, while maintaining its surfaces very close to room temperature,
to avoid the onset of seeing. In order to remove the heat, three configurations have been taken into consideration:
1) a flat 45° inclined heat rejecter, 2) a 45° conical heat rejecter and 3) a heat trap (made of a conical heat
rejecter and a cylindrical heat absorber). All devices include an air removal system to avoid the formation of
The European Solar Telescope (EST) is a European collaborative project to build a 4m class solar telescope in the
Canary Islands, which is now in its design study phase. The telescope will provide diffraction limited performance for
several instruments observing simultaneously at the Coudé focus at different wavelengths.
In order to guarantee the achievement of the demanding scientific requirements, error budgets of main performance have
been defined from the early design study phase in top-down fashion. During the design study, analyses are being
performed in order to update the defined error budgets in bottom-up fashion. Error budget management is proposed
from the design study phase to be used during the complete project life cycle.
The European Solar Telescope is a project for a 4-meter class telescope to be located in the Canary Islands. EST is
promoted by the European Association for Solar Telescopes (EAST). This is a consortium formed by a number of
research organizations from fifteen European countries (Austria, Croatia, Czech Republic, France, Germany, Hungary,
Italy, the Netherlands, Norway, Poland, Slovak Republic, Spain, Sweden, Switzerland, and United Kingdom). EST will
specialize in high spatial and temporal resolution using diverse instruments that can efficiently produce two-dimensional
spectropolarimetric information of the thermal, dynamic and magnetic properties of the plasma over many scale heights
in the solar atmosphere. In this contribution, the status of the development of the Design Study of EST is presented,
emphasizing the most important aspects of the optical design, mechanical structure, AO and MCAO systems for
wavefront correction, instruments and polarization analysis.
The European Solar Telescope (EST) is a European collaborative project to build a 4m class solar telescope in the
Canary Islands, which is now in its design study phase. The telescope will provide diffraction limited performance for
several instruments observing simultaneously at the Coudé focus at different wavelengths. A multi-conjugated adaptive
optics system composed of a tip-tilt mirror and several deformable mirrors will be integrated in the telescope optical
The secondary mirror system is composed of the mirror itself (Ø800mm), the alignment drives and the cooling system
needed to remove the solar heat load from the mirror. During the design study the feasibility to provide fast tip-tilt
capabilities at the secondary mirror to work as the adaptive optics tip-tilt mirror is also being evaluated.
The solar telescope EST is currently in the conceptual design phase. It is planned to be build on the Canary Islands until
end of the decade. It is specialized on polarimetric observations and will provide high spatial and spectral observations of
the different solar atmospheric layers.
The diameter of the primary mirror blank is 4.2m. Different types of mirror shapes were investigated with respect to
thermal and mechanical characteristics.
To remove the absorbed heat an air cooling system from the back side will be applied. Additional an air flushing system
will remove remaining warm air from the front side.
A major problem of a large open telescope will be the wind load. Results of the investigations will be shown. To achieve
optimal optical performance an active support system is planned. The primary mirror cell needs to be stiff enough to
support the primary mirror without deformation at strong wind in case of the open telescope option, but sufficient room
for the active support system and cooling system below the backside of the mirror is also required. Preliminary designs
and analysis results will be presented.
We introduce the concepts for the control and data handling systems of the European Solar Telescope (EST),
the main functional and technical requirements for the definition of these systems, and the outcomes from the
trade-off analysis to date. Concerning the telescope control, EST will have performance requirements similar to
those of current medium-sized night-time telescopes. On the other hand, the science goals of EST require the
simultaneous operation of three instruments and of a large number of detectors. This leads to a projected data
flux that will be technologically challenging and exceeds that of most other astronomical projects. We give an
overview of the reference design of the control and data handling systems for the EST to date, focusing on the
more critical and innovative aspects resulting from the overall design of the telescope.
The European Extremely Large Telescope (E-ELT) is a 42-m class optical telescope with a segmented primary mirror
composed of 984 segments which is currently being studied by ESO (European Southern Observatory). The segment
support system combines a series of mechanical whiffletrees for the axial support, a central diaphragm for lateral support
and a torsional constrainer. These elements are fixed to a common moving frame which is actively moved by means of
three actuators in piston and tip-tilt in order to keep the whole primary mirror in phase. The moving frame is fixed to the
segments subcells, which properly attach the segments to the cell structure, by means of special flexures, allowing large
axial alignment capability combined with high lateral stiffness. This paper describes the development of the support
system for the primary mirror segments of the E-ELT, which has been specified for a high stiffness and
eigenfrequencies, 60Hz for axial modes and 40Hz for lateral ones.
The GTC (Gran Telescopio Canarias) is an optical/IR telescope, with a 10,4 meter segmented primary, installed at the
Observatorio del Roque de Los Muchachos (ORM), at La Palma.
Past July 2007 it saw its First Light showing a very promising behaviour. The very good image quality achieved at that
an early stage of telescope commissioning is a direct consequence of the quality of its optics, the high performances of
its primary mirror control system, and the highly engineered telescope structure and servo system.
At present, we are advancing with the telescope commissioning whose first results are presented here. The two Day One
science instruments: OSIRIS and CanariCam are being prepared for installation and commissioning on the telescope.
Science verification are planned to be initiated by the end of 2008 and regular operation by March 2009.
The yoke of an alt-az telescope should provide a stiff interface between the azimuth journal and the tube of the telescope.
The stiffness of the yoke affects the performance of the telescope servosystem and its mass has an important contribution
on the total weight of the telescope.
Based on the design of the yoke of the GTC 10m telescope, a new configuration is analyzed in order to take advantage of
the azimuth journal to increase the stiffness and reduce the weight of the yoke. The performance of this configuration is
compared to that of the yoke of GTC.
The Gran Telescopio Canarias (GTC) is a 10m segmented mirror telescope that is under construction at the Observatorio
del Roque de los Muchachos (Spain) and that is expected to have first light during 2006.
The telescope mechanics is comprised of the telescope structure, bearings, motors, encoders, brakes, cable wraps and
counterweights and also the Nasmyth instrument rotators and the tertiary mirror drives. The structure of the telescope
was assembled at site between 2003 and 2005 and the rest of the systems are being assembled and tested during 2005
This paper presents the process of the assembly of the telescope mechanics, the problems presented and the lessons
learned during it, and the results of the tests performed.
In March 2004, the Commissioning Instrument (CI) for the GTC was accepted in the site of The Gran Telescopio Canarias (GTC) located in La Palma Island, Spain. During the GTC integration phase, the CI will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature Wave-front sensing (WFS), and high resolution Shack-Hartmann WFS. The imaging mode permits to qualify the GTC image quality. The Pupil Mode permits estimate the GTC stray light. The segments figure, alignment and cophasing verifications are made with both WFS modes. In this work we describe the Commissioning Instrument and show some tests results obtained during the site acceptance process at the GTC site.
In March 2004 was accepted in the site of Gran Telescopio Canarias (GTC) in La Palma Island, Spain, the Commissioning Instrument (CI) for the GTC. During the GTC integration phase, the CI will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature Wave-front sensing (WFS), and high resolution Shack-Hartmann WFS. This instrument was built by the Instituto de Astronomia UNAM in Mexico City and the Centro de Ingenieria y Desarrollo Industrial (CIDESI) in Queretaro, Qro under a GRANTECAN contract after an international public bid. Some optical components were built by Centro de Investigaciones en Optica (CIO) in Leon Gto and the biggest mechanical parts were manufactured by Vatech in Morelia Mich. In this paper we made a general description of the CI and we relate how this instrument, build under international standards, was entirely made in Mexico.
ELMER is a multi-purpose instrument for the GTC designed for both, Imaging and Spectrosopy in the visible range. The CCD camera employs a E2V Technologies CCD44-82 detector mounted in a high performance LN2 Bath Cryostat based on an ESO design and a SDSU-II CCD controller with parallel interface. The design including the low-noise fan-out electronics has been kept flexible to allow alternatively the use of MIT/LL CCID-20 detectors. We present the design of the CCD camera and data acquisition system and first performance test results.
ELMER is an instrument for the GTC designed to observe between 365 and 1000 nm. The observing modes for the instrument at Day One shall be: Imaging, Long Slit and Mask-Multi-object Spectroscopy, Slit-less multi-object spectroscopy, Fast Photometry and Fast short-slit spectroscopy, over a FOV of 4.2 arcmin diameter. Spectral resolutions of 250, 1000 and 2500, covering the whole spectral range, will be available. ELMER has been designed and managed within the GTC Project Office. ELMER is currently in the final stage of testing previous to be shipped to the Observatory. The general description of this instrument and its expected scientific performance are summarised.
The GTC Acquisition Cameras and Wavefront Sensors are based on a modular design with remote, low-profile and lightweight CCD heads and a compact CCD controller. The cameras employ E2V Technologies Peltier cooled CCD47-20 and CCD39-01 detectors, which achieve 1Hz and 200Hz full frame readouts, respectively. The CCD controller is a modified version of the Magellan CCD controller (Greg Burley - OCIW), which is linked to the GTC control system. We present the detailed design and first performance results of the cameras.
Elmer is a visible imager and spectrograph for the Gran Telescopio Canarias, which has been designed in-house. The major features and some of the analysis done are shown for each optical assembly. The image error budget is presented with the current estimations, as well as the foreseen acceptance tests. Finally the present status of the optics is presented.
ELMER is an optical instrument for the GTC designed to observe between 370 and 1000 nm. The observing modes for the instrument at Day One shall be: imaging, long slit spectroscopy, slit-less multi-object spectroscopy, fast photometry, fast short-slit spectroscopy and mask multi-object spectroscopy. It will be installed at the Nasmyth-B focal station at Day One, but it has also been designed to operate at the Folded Cassegrain focal station. The physical configuration of the instrument consists of a front section where the focal plane components are mounted (cover masks and slits) and a rear section with the rest of the components (field lens, folder mirrors, collimator, shutter, filters, prisms, grisms, camera and cryostat). Both sections are connected through a hexapod type structure.
An accurate behavior model of the instrument has been developed to optimize the design of the structural parts. The geometry of the hexapod configuration has been adjusted to reduce the ratio between the lateral deflection of the rear section and its rotation in order to minimize the image motion due to the deflections of the instrument. Special effort has been devoted to the design of the drives of the four wheels, each one driven by a preloaded worm gear.
Elmer is an imager and spectrograph in the visible wavelength range for the Gran Telescopio CANARIAS, GTC. Elmer is being managed directly by the GTC Project Office, who has done the whole Preliminary Design and large part of the Detailed Design. This instrument shall operate at the telescope on Day One, as a back up in case of delays of the major instruments, guaranteeing the scientific return of the GTC. A brief presentation of the instrument is here given. The expected scientific performance of the instrument is summarized. Finally, the general description of the management strategy and project parameters are described.
Under a contract with the GRANTECAN, the Commissioning Instrument is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center.
This paper will discuss in some detail the final Commissioning Instrument (CI) mechanical design and fabrication. We will also explain the error budget and the barrels design as well as their thermal compensation. The optical design and the control system are discussed in other papers.
The CI will just act as a diagnostic tool for image quality verification during the GTC Commissioning Phase. This phase is a quality control process for achieving, verifying, and documenting the performance of each GTC sub-systems. This is a very important step for the telescope life. It will begin on starting day and will last for a year.
The CI project started in December 2000. The critical design phase was reviewed in July 2001. The CI manufacturing is currently in progress and most parts are finished. We are now approaching the factory acceptance stage.
Under a contract with the GRANTECAN, the Commissioning Instrument (CI) is a project developed by a team of Mexican scientists and engineers from the Instrumentation Department of the Astronomy Institute at the UNAM and the CIDESI Engineering Center. The CI will verify the Gran Telescopio Canarias (GTC) performance during the commissioning phase between First Light and Day One. The design phase is now completed and the project is currently in the manufacturing phase.
The CI main goal is to measure the telescope image quality. To obtain a stable high resolution image, the mechanical structures should be as rigid as possible. This paper describes the several steps of the conceptual design and the Finite Element Analysis (FEA) for the CI mechanical structures.
A variety of models were proposed. The FEA was useful to evaluate the displacements, shape modes, weight, and thermal expansions of each model. A set of indicators were compared with decision matrixes. The best performance models were subjected to a re-optimization stage. By applying the same decision method, a CI Structure Model was proposed. The FEA results complied with all the instruments specifications. Displacements values and vibration frequencies are reported.
During the GTC integration phase, the Commissioning Instrument (CI) will be a diagnostic tool for performance verification. The CI features four operation modes-imaging, pupil imaging, Curvature WFS, and high resolution Shack-Hartmann WFS. After the GTC Commissioning we also plan to install a Pyramid WFS. This instrument can therefore serve as a test bench for comparing co-phasing methods for ELTs on a real segmented telescope. In this paper we made a general instrument overview.
The Gran Telescopio Canarias (GTC) is a 10 m-class telescope which is under construction and will be operational at the Observatorio del Roque de Los Muchachos at the end of 2003. The goal of this paper is to describe the current status of the design and construction of the primary, secondary and tertiary mirrors of the GTC and their opto-mechanical supports. It also summarizes the optical performances expected from the GTC and the error budget of the optical system.
Modern Acquisition and Guiding systems provide a range of services with the aim of optimizing telescope performance. These include wavefront sensing for active optics, fast guiding and measurement of seeing. On a segmented-mirror telescope, the Acquisition and Guiding system may also be expected to provide measurements of the piston errors between the primary mirror segments. The Guacamole (GUiding, Acquisition and CAlibration MOduLE) system of the 10 m Gran Telescopio Canarias (GTC) has been designed to provide all of these services. Complete systems will be installed at each of the GTC Nasmyth foci. The requirements of this system are presented and a preliminary design is described.
ABEL is currently at the beginning of the design phase at the Instituto de Astrofisica de Canaris. The instrument will be equipped with the 256 X 256 Santa Barbara Research Corporation InSb FPA which will provide a working spectral range from 1 to 5 microns. For image mode three different platescales are envisaged: 0.2 inch/pixel, to be used in the thermal IR to avoid detector saturation; 0.4 inch/pixel, which will allow for sufficient sampling of the median seeing limited images below 2.5 microns; and 1.0 inch/pixel, which will be the standard in spectroscopic operations and during wide field imaging. For spectroscopy, a standard moderate spectral resolution of about 400 will be available in the JHKLM windows, which will be all fully covered in a single exposure. Additional higher spectral resolution is under consideration, which at least double. ABEL will offer a wide variety of slit widths and shapes, ranging from 1 inch to 3 inches, and including dog-leg shape. The thermal design is based on a two stages closed cycle cooler, the first stage being used for the passive optics while the second will cool directly the detector to about 30 to 40 K. The instrument is planned for the late 99 and a major cooperation with the Osservatorio de Arcetri is underway. ABEL will be installed in the f/13.8 Cassegrain focus of the 1.5m Telescopio Carlos Sanchez, at the Spanish Observatorio de El Teide, in the canarian island of Tenerife.
INTEGRAL is an optical fiber unit for performing 2D spectroscopy of extended objects at the 4.2 m. William Herschel Telescope (WHT). It is mounted at the GHRIL Nasmyth focus together with newly built acquisition, guiding, and calibration units. It makes use of the specially designed fiber spectrograph WYFFOS. This system allows up to six bundles to be mounted simultaneously. It currently contains three science oriented fiber bundles, any one of which can be easily and quickly placed in the telescope beam. Their spatial resolution elements (fiber core diameters) are 0'.45, 0'.9, and 2'.7, respectively. Hence, depending on the prevailing seeing conditions the instrument can be easily optimized for the scientific program. INTEGRAL was successfully commissioned at the WHT during a six night period in July 1997. Here we will discuss its main characteristics.