The SITELLE Imaging Fourier Transform Spectrometer was successfully commissioned at the Canada France Hawaii Telescope starting in July 2015. Here we discuss the commissioning process, the outcome of the early tests on-sky as well as the ensuing work to optimize the modulation efficiency at large optical path difference and the image quality of the instrument.
The Canada-France-Hawaii Telescope (CFHT) completed the first phase of its TCS upgrade in early 2015. Prior to this effort, the previous version of CFHTs TCS was largely unmodified since it began operation in 1979 and had begun to exhibit reliability and maintainability issues entering its third decade of operation. The first phase consisted of replacing the custom-built servo control hardware built by the Canadian Marconi Company with an off-the-shelf Delta Tau Systems Power PMAC and replacing the absolute and incremental encoders with modern equivalents. Adapting the motion control algorithms used within the Power PMAC for real-time control of the telescope on the sky posed unique challenges. This work brie y summarizes the design for the upgraded TCS at CFHT, describes the solutions that adapted the traditional use of the Power PMAC for use at CFHT, and discusses the improved performance of CFHTs new TCS in terms of decreased time to target and tracking error.
The Maunakea Laser Traffic Control System (LTCS) has been in use since 2002 providing a mechanism to prevent the laser guide star or Rayleigh scatter from a laser propagated from one telescope from interfering with science observations at any of the other telescopes that share the mountain. LTCS has also been adopted at several other astronomical sites around the world to address that same need. In 2014 the stakeholders on Maunakea began the process of improving LTCS capability to support common observing techniques with enhanced First On Target (FoT) equity. The planned improvements include support for non-sidereal observing, laser checkout at zenith, dynamic field of view size, dithering, collision calculations even when a facility is not laser impacted, multiple alert severity levels, and software refactoring. The design of these improvements was completed in early 2015, and implementation is expected to be completed in 2016. This paper describes the Maunakea LTCS collaboration and the design of these planned improvements.
SPIRou is a near-IR (0.98-2.35μm), echelle spectropolarimeter / high precision velocimeter being designed as a nextgeneration
instrument for the 3.6m Canada-France-Hawaii Telescope on Mauna Kea, Hawaii, with the main goals of
detecting Earth-like planets around low-mass stars and magnetic fields of forming stars. The unique scientific and
technical capabilities of SPIRou are described in a series of eight companion papers. In this paper, the means of
controlling the instrument are discussed. Most of the instrument control is fairly normal, using off-the-shelf components
where possible and reusing already available code for these components. Some aspects, however, are more challenging.
In particular, the paper will focus on the challenges of doing fast (50 Hz) guiding with 30 mas repeatability using the
object being observed as a reference and on thermally stabilizing a large optical bench to a very high precision (~1 mK).μ
The Canada-France-Hawaii Telescope (CFHT) has been in operation since 1979. The Telescope Control System (TCS)
has undergone software changes since the beginning of science operation but the original hardware has largely been
untouched except for an upgrade to the time system and host computer. Telescope performance has not been an issue
although some improvements are desirable. However, parts obsolescence will become a problem as the telescope enters
it third decade of operation. Although there are sufficient spare parts currently, many are no longer readily available.
Some critical components, such as encoders and VME CPU boards are no longer available. The TCS upgrade project
addresses the obsolete and obsolescent issues to ensure operational capability through 2025. It seeks to modernize and
simplify the electronics and to take advantages of the advancement made in stand-alone servo controllers.
In an effort to reduce the amount of time spent focusing the telescope and to improve the quality of the focus, a new
procedure has been investigated and implemented at the Canada-France-Hawaii Telescope (CFHT). The new procedure
is based on a paper by Tokovinin and Heathcote and requires only two out-of-focus images to determine the best focus
for the telescope. Using only two images provides a great time savings over the five or more images required for a
standard through-focus sequence. In addition, it has been found that this method is significantly less sensitive to seeing
variations than the traditional through-focus procedure, so the quality of the resulting focus is better. Finally, the new
procedure relies on a second moment calculation and so is computationally easier and more robust than methods using a
FWHM calculation. The new method has been implemented for WIRCam for the past 18 months, for MegaPrime for
the past year, and has recently been implemented for ESPaDOnS.
VASAO is an ambitious project that explores new conceptual direction in the field of astronomical adaptive optics. In
the era of 8 meter and larger telescopes, and their instrument costs and telescope time pressure, there is a natural niche
for such ground-breaking conceptual development in the 4 meter class telescope. The aim of VASAO is to provide
diffraction limited imaging in the visible with 100% sky coverage; the challenge (but potential rewards) arises from the
simultaneity of these requirements. To this end, CFHT is conducting a feasibility study based on the polychromatic
guide star concept (Foy et al., 1995 ) coupled with a high order curvature AO system, presented in this paper.
A number of experiments have been started (or carried out) to study the challenges and limits of the techniques involved
in an operational setting; these include the FlyEyes detector, and a polychromatic tip-tilt test on natural stars.
Because such a project straddles such a fine line between facility instrument and experimental facility, careful thought
has to be given to the balance between modes of operations and potential astrophysical targets.
The Canada-France-Hawaii Telescope (CFHT) is now operating a Wide Field Infrared Camera (WIRCam) with a 20.5' x 20.5' field of view. The camera uses a mosaic of four Rockwell HAWAII-2RG detectors enabling subsample readouts at a rate of 50Hz for guiding and fast parallel readout of 32 amplifiers per detector for science. This paper will discuss the software architecture and implementation used to optimize the scientific productivity of the instrument as well as our experience during the first semester of use.
WIRCam (Wide-field InfraRed Camera) is a near-infrared (0.9-2.4 microns) camera developed for the prime focus of the Canada France Hawaii Telescope (CFHT), a 3.6-m telescope located on Mauna Kea, Hawaii. WIRCam is based on 4 x 2048x2048 HAWAII2RG arrays, developed by Rockwell. The camera provides a 0.3"/pixel sampling, and the close packaging of the detectors allows to cover an almost contiguous field-of-view of 20.5' x 20.5'. All optical elements are assembled in a cryovessel and cooled down to 85K by a He closed cycle cryogenerator. The two filter wheels have capacity for 8 filters (110 mm in diameter), cooled at low temperature together with the Lyot stop. These wheels are mounted on sapphire ball bearings and powered by external motors. Passive spring indexers define their positioning. A fused-silica tip/tilt plate powered by voice coil type motors provides image stabilization in front of the cryovessel. It compensates for flexures as well as for low frequency telescope oscillations from wind shake. This paper describes the overall architecture of the camera, giving the optical estimated performances and details some specific points of the design such as filter wheels, thermal connections, etc.
The Canada-France-Hawaii Telescope is now operating a wide-field visible camera with a one-degree field of view. We have developed a guiding and auto-focus system that uses two stage-mounted CCD cameras fed by Shack-Hartmann optics providing position and focus error signals to the telescope guiding and focus control systems. The two camera stages patrol guide fields separated by more than a degree, one to the north and one to the south of the main camera field. Guiding generates a 50 Hz correction signal applied to a tip-tilt plate in the light path and a low frequency correction signal sent to control telescope position. During guiding a focus error signal is used to adjust telescope focus. Calibration issues include guide camera focusing, image distortion produced by the wide field corrector, guide stage positioning, and determining ideal guide star positions on the cameras. This paper describes the resulting system, including preselected guide star acquisition, guiding, telescope focus control, and calibration.
The Canada-France-Hawaii Telescope Adaptive Optics system has now been on the sky for two years. During that time it has been installed on the telescope 13 + times with over 100 nights of scheduled observing time. It is routinely producing red and near IR images with 0.10 arcsecond full- width half-max under median seeing conditions. We present the experience we have gained using this system. We discuss installation and set up including characterization, tuning, and focusing. We consider observer training on and following use of the system. And we consider support issues.
Complex instruments generally have complex control requirements. However theoretical analysis, instrument design, and software planning can allow a simple user interface to control the instrument successfully. A case in point is the Canada-France- Hawaii Telescope Adaptive Optics system. In normal operation one button push is sufficient to begin adaptive correction. During system design much effort was placed in automatic gain optimization for bimorph mirror control. This has allowed the system to run unattended for hours at a time. During software design and development other control points were identified and decision paths formulated to allow their parameters to be adjusted automatically. So, although a complete engineering interface was designed and implemented, in practice it has only been used for initial development and acceptance testing. Normal observing needs only a simple form for the astronomer. We present the resulting interface and trace some of the design decisions that allowed us to simplify this potentially complex interface.
The adaptive optics instrument adaptor for the 3.6 m Canada- France-Hawaii telescope (CFHT) is currently in the commissioning phase. The heart of the system is a 19 electrode bimorph mirror (1:6:12), used with a 19 sub-aperture, curvature wave-front sensor and a separate tip-tilt re-imaging mirror. The performance evaluated in the laboratory and on the sky are presented: the adaptive optics control system provides a 100 Hz servo bandwidth with modal control capabilities. We report astronomical images with median Strehl ratio of 20 (at 1.25 micrometer) to 60% (at 2.2 micrometer), with a FWHM of 0.1 arcsec and a sensitivity allowing image quality improvement with guide stars as faint as m<SUB>R</SUB> equals 17.