After 20 years of operations, the Paranal Observatory has accumulated some experience with maintenance of systems, and has lately adopted the methodology called ‘Maintien en Condition Operationnelle’ (MCO). We will describe and review the practical implementation of this strategy, the tools used, the benefits and challenges as well as practical examples and how it is overall managed. The approach is also a benchmarking exercise for operation of the ESO-ELT in the future.
Gemini South's instrument suite has been completely transformed since our last biennial update. We commissioned
the Gemini Multi-Conjugate Adaptive Optics System (GeMS) and its associated Gemini South Adaptive Optics
Imager (GSAOI) as well as Flamingos-2, our long-slit and multi-object infrared imager and spectrograph, and the
Gemini Planet Imager (GPI). We upgraded the CCDs in GMOS-S, our multi-object optical imager and spectrograph,
with the GMOS-N CCD upgrade scheduled for 2015. Our next instrument, the Gemini High-resolution Optical
SpecTrograph (GHOST) is in its preliminary design stage and we are making plans for the instrument to
The Gemini Multi-Conjugate Adaptive Optics System (GeMS) began its on-sky commissioning in January 2011.
The system provides high order wide field corrections using a constellation of five Laser Guide Stars. In December 2011, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band) over an 87 x 87 arcsecond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: “GeMS on-sky results”, Rigaut et al. Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS.
The Gemini Observatory is going through an extraordinary time with astronomical instrumentation. New powerful
capabilities are delivered and are soon entering scientific operations. In parallel, new instruments are being planned and
designed to align the strategy with community needs and enhance the competitiveness of the Observatory for the next
decade. We will give a broad overview of the instrumentation program, focusing on achievements, challenges and
strategies within a scientific, technical and management perspective. In particular we will discuss the following
instruments and projects (some will have dedicated detailed papers in this conference): GMOS-CCD refurbishment,
FLAMINGOS-2, GeMS (MCAO system and imager GSAOI), GPI, new generation of A&G, GRACES (fiber feed to
CFHT ESPaDOnS) and GHOS (Gemini High-resolution Optical Spectrograph), and provide some updates about
detector controllers, mid-IR instruments, Altair, GNIRS, GLAO and future workhorse instruments.
The Gemini North (GN) AO system, Altair, has been routinely operating in LGS mode since 2007. Due to the initial
optical design, the NGS field-of-view (FoV) is limited to a radius ~ 25" which limits the potential science. To improve
this, we have tested the AO/LGS operation using a peripheral wavefront sensor (PWFS) whose patrol field is ~ 4'-7'
from the target. This expanded NGS FoV permits greater sky coverage but with decreased resolution, FWHM ~ 0.1" -
0.2" making this mode very suitable for non-imaging spectrographic and integral field unit observations. We present the
hardware and software upgrades to PWFS and Altair as well as the software necessary for making this observing mode a
routine and integral part of GN operations. Characterization and performance of this new operation mode, known as
LGS+P1, are presented.
With two to three deformable mirrors, three Natural Guide Stars (NGS) and five sodium Laser Guide Stars (LGS), the
Gemini Multi-Conjugate Adaptive Optics System (Gemini MCAO a.k.a. GeMS) will be the first facility-class MCAO
capability to be offered for regular science observations starting in 2013A. The engineering and science commissioning
phase of the project was kicked off in January 2011 when the Gemini South Laser Guide Star Facility (GS LGSF)
propagated its 50W laser above the summit of Cerro Pachón, Chile. GeMS commissioning has proceeded throughout
2011 and the first half of 2012 at a pace of one 6- to 10-night run per month with a 5-month pause during the 2011
This paper focuses on the LGSF-side of the project and provides an overview of the LGSF system and subsystems, their
top-level specifications, design, integration with the telescope, and performance throughout commissioning and beyond.
Subsystems of the GS LGSF include: (i) a diode-pumped solid-state 1.06+1.32 micron sum-frequency laser capable of
producing over 50W of output power at the sodium wavelength (589nm); (ii) Beam Transfer Optics (BTO) that transport
the 50W beam up the telescope, split the beam five-ways and configure the five 10W beams for projection by the Laser
Launch Telescope (LLT) located behind the Gemini South 8m telescope secondary mirror; and (iii) a variety of safety
systems to ensure safe laser operations for observatory personnel and equipment, neighbor observatories, as well as
passing aircrafts and satellites.
The vast majority of large telescopes are now equipped with Adaptive Optics (AO) systems, and many use lasers to
create artificial stars (laser guide stars, LGS). Despite the significant advances in the use of LGS for AO, some problems
persist during the operations. In particular, achieving a satisfactory performance in terms of on-sky laser power and beam
quality usually requires frequent and complex alignments of the laser system, beam transfer optics and launch telescope.
To provide easier calibrations and faster pre-setting of the LGS facility during routine operations, we propose the
introduction of active elements (deformable mirrors) in the laser beam before it is propagated to the sky. The paper
studies an AO configuration with two deformable mirrors to correct for quasi-static and dynamic aberrations. The
problem of determining the correction phases to apply to the deformable mirrors is particularly challenging due to the
highly nonlinear problem and the possible appearance of branch points. We propose an iterative method based on a
phase retrieval algorithm that uses a weighted least squares unwrapper to avoid branch points. Simulations are performed
aiming to a future implementation in the Gemini Multi-conjugate-adaptive-optics System (GeMS). Results show that the
technique is accurate and robust, with a reasonable convergence speed.
GeMS, the Gemini Laser Guide Star Multi-Conjugate Adaptive Optics facility system, has seen first light in December 2011, and has already produced images with H band Strehl ratio in excess of 35% over fields of view of 85x85 arcsec, fulfilling the MCAO promise. In this paper, we report on these early results, analyze trends in performance, and concentrate on key or novel aspects of the system, like centroid gain estimation, on-sky non common path aberration estimation. We also present the first astrometric analysis, showing very encouraging results.
The Gemini Multi-Conjugate Adaptive Optics System (GeMS} began its on-sky commissioning in January 20ll. The system provides high order wide-field corrections using a constellation of five Laser Guide Stars. In December 20ll, commissioning culminated in images with a FWHM of 80±2mas at 1.65 microns (H band} over an 87 x 87 arcsccond field of view. The first images have already demonstrated the scientific potential of GeMS, and after more than a year of commissioning GeMS is finally close to completion and ready for science. This paper presents a general status of the GeMS project and summarizes the achievements made during more than a year of commissioning. The characterization of GeMS performance is presented in a companion paper: "GeMS on-sky results" , R.igaut ct al. Here we report on the sub-systems' performance, discuss current limitations and present proposed upgrades. The integration of GeMS into the observatory operational scheme is detailed. Finally, we present the plans for next year's operations with GeMS.
GeMS (the Gemini Multi-conjugated adaptive optics System) is a facility instrument for the Gemini-South
telescope. It will deliver a uniform, diffraction-limited image quality at near-infrared (NIR) wavelengths over an
extended FoV or more than 1 arcmin across. GeMS is a unique and challenging project from the technological
point of view and because of its control complexity. The system includes 5 laser guide stars, 3 natural guide
stars, 3 deformable mirrors optically conjugated at 0, 4.5 and 9km and 1 tip-tilt mirror. After 10 years since
the beginning of the project, GeMS is finally reaching a state in which all the subsystems have been received,
integrated and, in the large part, tested. In this paper, we report on the progress and current status of the
different sub-systems with a particular emphasis on the calibrations, control and optimization of the AO bench.
As part of its Safe Aircraft Localization and Satellite Acquisition System (SALSA), Gemini is building an All Sky Camera (ASCAM) system to detect aircrafts in order to prevent propagation of the laser that could be a safety hazard for pilots and passengers. ASCAM detections, including trajectory parameters, are made available to neighbor observatories so they may compute impact parameters given their location. We present in this paper an overview of the system
architecture, a description of the software solution and detection algorithm, some performance and on-sky result.
We present Canopus, the AO bench for Gemini's Multi Conjugate Adaptive Optics System (GEMS), a unique facility for
the Gemini South telescope located at Cerro Pachon in Chile. The MCAO system uses five laser beacons in conjunction
with different natural guide stars configurations. A deployable fold mirror located in the telescope Acquisition and
Guiding Unit (A&G) sends the telescope beam to the entrance of the bench. The beam is split within Canopus into three
main components: two sensing paths and the output corrected science beam. Light from the laser constellation (589nm)
is directed to five Shack-Hartman wave front sensors (E2V-39 CCDs read at 800Hz). Visible light from natural guide
stars is sent to three independent sensors arrays (SCPM AQ4C Avalanche Photodiodes modules in quad cell
arrangement) via optical fibers mounted on independent stages and a slow focus sensor (E2V-57 back-illuminated
CCD). The infrared corrected beam exits Canopus and goes to instrumentation for science. The Real Time Controller
(RTC) analyses wavefront signals and correct distortions using a fast tip-tilt mirror and three deformable mirrors
conjugated at different altitudes. The RTC also adjusts positioning of the laser beacon (Beam Transfer Optics fast
steering array), and handles miscellaneous offloads (M1 figure, M2 tip/tilt, LGS zoom and magnification corrections,
NGS probes adjustments etc.). Background optimizations run on a separate dedicated server to feed new parameters into
The Gemini Observatory is in the final integration and test phase for its Multi-Conjugate Adaptive Optics (MCAO)
project at the Gemini South 8-meter telescope atop Cerro Pachón, Chile. This paper presents an overview and status of
the laser-side of the MCAO project in general and its Beam Transfer Optics (BTO), Laser Launch Telescope (LLT) and
Safety Systems in particular. We review the commonalities and differences between the Gemini North Laser Guide Star
(LGS) facility producing one LGS with a 10W-class laser, and its southern sibling producing five LGS with a 50W-class
laser. We also highlight the modifications brought to the initial Gemini South LGS facility design based on lessons
learned over 3 years of LGS operations in Hawaii. Finally, current integration and test results of the BTO and on-sky
LLT performance are presented. Laser first light is expected in early 2009.
The Laser Service Enclosure (LSE) is an environmentally controlled ISO 7 clean room designed to house, protect and
provide environmental control for the Gemini South multi-conjugate adaptive optics laser system. The LSE is 8.0 meters
long, 2.5 meters wide and 2.5 meters high with a mass of approximately 5,100 kg. The LSE shall reside on a new
telescope Nasmyth platform named the Support Structure (SS). The SS is a three-dimensional beam and frame structure
designed to support the LSE and laser system under all loading conditions. This paper will review the system
requirements and describe the system hardware including optical, environmental, structural and operational issues as
well as the anticipated impact the system will have on the current telescope performance.
The Gemini twins were the first large modern telescopes to receive protected silver coatings on their
mirrors in 2004. The low emissivity requirement is fundamental for the IR optimization. In the mid-IR a
factor of two reduction in telescope emissivity is equivalent to increasing the collecting area by the same
factor. Our emissivity maintenance requirement is very stringent: 0.5% maximum degradation during
operations, at any single wavelength beyond 2.2 μm.
We developed a very rigorous standard to wash the primary mirrors in the telescope without science
down time. The in-situ washes are made regularly, and the reflectivity and emissivity gains are significant.
The coating lifetime has been extended far more than our original expectations. In this report we describe the
in-situ process and hardware, explain our maintenance plan, and show results of the coating performance over
The Gemini Multi-Conjugate Adaptive Optics project was launched in April 1999 to become the Gemini South
AO facility in Chile. The system includes 5 laser guide stars, 3 natural guide stars and 3 deformable mirrors optically
conjugated at 0, 4.5 and 9km to achieve near-uniform atmospheric compensation over a 1 arc minute square field of
Sub-contracted systems with vendors were started as early as October 2001 and were all delivered by July
2007, but for the 50W laser (due around September 2008). The in-house development began in January 2006, and is
expected to be completed by the end of 2008 to continue with integration and testing (I&T) on the telescope. The on-sky
commissioning phase is scheduled to start during the first half of 2009.
In this general overview, we will first describe the status of each subsystem with their major requirements, risk
areas and achieved performance. Next we will present our plan to complete the project by reviewing the remaining steps
through I&T and commissioning on the telescope, both during day-time and at night-time. Finally, we will summarize
some management activities like schedules, resources and conclude with some lessons learned.
Besides the increasing use of adaptive optics (AO) on modern telescopes, active optics (aO) are still of high importance to optimize Image Quality (IQ) for non-AO instruments and decrease the dynamic range needed for AO corrections. We will describe the design and operation of an optical alignment bench used to calibrate the aO models of the peripheral wavefront sensors. This setup is used to determine optical models in stable conditions in the laboratory and thus optimize wavefront correction on the sky. We will show results of this technique applied to our 2x2 Shack-Hartmann wavefront sensor used for tip-tilt-focus-astigmatism correction of all our non-AO instruments. We will also review some sub-systems performance monitoring tools and finally gauge the performance of active optics on the Gemini telescopes by analyzing the delivered image quality for various instruments.
The Gemini twins were the first large modern telescopes to receive protected Silver coatings on their mirrors in 2004.
We report the performance evolution of these 4-layer coatings in terms of reflectivity and emissivity. We evaluate the
durability of these thin films by comparison to the evolution of some samples that we have produced and exposed since
2002. Finally, we will explain our maintenance plan.
The Large Synoptic Survey Telescope (LSST) baseline design includes aluminum coating for the large mirrors in its 3 element modified Paul Baker optical design. The 8.4 meter diameter of the primary provides a significant challenge to the LSST coating plans however such coatings have successfully achieved for this size aperture. LSST also recognizes that the use of mirror coatings with higher reflectivity and durability would significantly benefit its science by increasing its overall throughput and improving its operational efficiency. LSST has identified Lawrence Livermore National Laboratory (LLNL) blue-shifted protected silver coating as a possible candidate to provide this blue wavelength performance. A study has been started to assess the performance of these and other coatings in the observatory environment. We present the details of this ongoing program, the results obtained so far, and related coating tests results. LSST has also engaged in collaboration with the Gemini Telescope in the development and testing of an Al-Ag coating based on their current recipe. The first results of these tests are also included in this report.
Altair is the general-purpose Adaptive Optics bench installed on Gemini North that has operated successfully with
Natural Guide Star (NGS) since 2003. The original design and fabrication included an additional WaveFront Sensor
(WFS) to enable operation with Laser Guide Star (LGS). Altair has been recently upgraded and functional
commissioning was performed between June and November 2005. The insertion of a dichroic beamsplitter in the
NGS path allows to reflect the 589nm light to the LGS wavefront sensor and transmit the visible light of the NGS (or
Tip-Tilt Guide star -TTGS-) to the tip-tilt-focus sensors. We will review the various modifications made for this dual
operation, both in hardware and software, and describe the steps and results of the integration and testing phase on the
We briefly describe the SOAR Optical Imager (SOI), the first light instrument for the 4.1m SOuthern Astronomical Research (SOAR) telescope now being commissioned on Cerro Pachón in the mountains of northern Chile. The SOI has a mini-mosaic of 2 2kx4k CCDs at its focal plane, a focal reducer camera, two filter cartridges, and a linear ADC. The instrument was designed to produce precision photometry and to fully exploit the expected superb image quality of the SOAR telescope over a 5.5x5.5 arcmin2 field with high throughput down to the atmospheric cut-off, and close reproduction of photometric pass-bands throughout 310-1050 nm. During early engineering runs in April 2004, we used the SOI to take images as part of the test program for the actively controlled primary mirror of the SOAR telescope, one of which we show in this paper. Taken just three months after the arrival of the optics in Chile, we show that the stellar images have the same diameter of 0.74" as the simultaneously measured seeing disk at the time of observation. We call our image "Engineering 1st Light" and in the near future expect to be able to produce images with diameters down to 0.3" in the R band over a 5.5' field during about 20% of the observing time, using the tip-tilt adaptive corrector we are implementing.
The Gemini telescopes were designed to be infrared-optimized. Among the features specified for optimal performance is the use of silver-based coatings on the mirrors. The feasibility study contracted by Gemini in 1994-1995 provided both techniques and recipes to apply these high-reflectivity and low-emissivity films. All this effort is now being implemented in our coating plants. At the time of the study, sputtering experiments showed that a reflectivity of 99.1% at 10μm was achievable. We have now produced bare and protected silver sputtered films in our coating plants and conducted environmental testing, both accelerated and in real-life conditions, to assess the durability. We have also already applied, for the first time ever, protected-silver coatings on the main optical elements (M1, M2 and M3) of an 8-m telescope. We report here the progress to date, the performance of the films, and our long-term plans for mirror coatings and maintenance.
The SOAR Optical Imager (SOI) is the commissioning instrument for the 4.2-m SOAR telescope, which is sited on Cerro Pachón, and due for first light in April 2003. It is being built at Cerro Tololo Inter-American Observatory, and is one of a suite of first-light instruments being provided by the four SOAR partners (NOAO, Brazil, University of North Carolina, Michigan State University). The instrument is designed to produce precision photometry and to fully exploit the expected superb image quality of the SOAR telescope, over a 6x6 arcmin field. Design goals include maintaining high throughput down to the atmospheric cut-off, and close reproduction of photometric passbands throughout 310-1050nm. The focal plane consists of a two-CCD mosaic of 2Kx4K Lincoln Labs CCDs, following an atmospheric dispersion corrector, focal reducer, and tip-tilt sensor. Control and data handling are within the LabVIEW-Linux environment used throughout the SOAR Project.
The new operations model for the CTIO Blanco 4-m telescope will use a small suite of fixed facility instruments for imaging and spectroscopy. The Infrared Side Port Imager, ISPI, provides the infrared imaging capability. We describe the optical, mechanical, electronic, and software components of the instrument. The optical design is a refractive camera-collimator system. The cryo-mechanical packaging integrates two LN2-cooled dewars into a compact, straightline unit to fit within space constraints at the bent Cassegrain telescope focus. A HAWAII 2 2048 x 2048 HgCdTe array is operated by an SDSU II array controller. Instrument control is implemented with ArcVIEW, a proprietary LabVIEW-based software package. First light on the telescope is planned for September 2002.
In the near future several astronomical observatories in Chile are planning to use sodium laser guide stars to increase the sky coverage provided by their adaptive optics facilities. Knowledge of the mesospheric sodium layer behavior is crucial to predict the performance of future laser guide star adaptive optics systems. Whereas the sodium layer has been observed quite extensively at several locations, many of them in the Northern Hemisphere, very little measurements have been made in Chile. The Gemini Observatory therefore initiated a year-long sodium monitoring campaign at the Cerro Tololo Inter-American Observatory located only a few kilometers away from the Gemini South telescope where a conventional laser guide star facility will be offered to the community in 2005, soon to be upgraded to a multi-conjugate adaptive optics system with five laser guide stars. This paper reports on the laser-based sodium monitoring experimental set up and data reduction techniques, and presents some preliminary results on the sodium column density and layer altitude variations observed from February 2001 to February 2002. Implications for the Gemini South Adaptive Optics system expected performance are presented as well.
The Giant Segmented Mirror Telescope (GSMT), along with other proposed Extremely Large Telescopes (ELT's) with apertures over 20-m, is likely to impose rather different site selection criteria than those for existing large telescopes. Advantageously, remote-sensing techniques allow rather more objective comparisons than was possible in the past, and the general task is aided by numerical modeling and new ground-based measurement techniques. In recognition of the difficulty of the site-selection process, co-operation between the several ELT projects is the norm. A description is given of the site survey for the GSMT, begun in late 1999, and now part of the GSMT studies and evaluation project, run by the Associated Universities for Research in Astronomy (AURA) New Initiatives Office (NIO).
ABU is a NOAO IR imaging camera designed for evaluating the performance of the 1024x1024 Aladdth InSb array. For this experiment, it was outfitted with five filters (see Figure 9) m the 3-5 micron range to exploit the low water vapor and lower air temperatures at the South Pole. At the South Pole it was integrated with the CARA SPIREX (South Pole Infrared Explorer) telescope. Figure 1 is a picture of the telescope showing the environmental box (the white box by the author). which protected ABU and its electronics from ambient environmental conditions.
One of the problems encountered when using single-mode fibers in a wideband interferometer is the dispersion of the waveguide. By optimizing the waveguide structure for an actual fluoride glass, a fiber can be made whose dispersion between 2 micrometers and 2.7 micrometers is reduced by more than two orders of magnitude. Simulated interferograms show that an interferometer using such a fiber could withstand a fiber length difference of 10m without a substantial degradation of its performances. This raises the possibility to consider all-fiber delay lines with several meters of optical path delay variation.