Kevin Ho

Maunakea spectroscopic explorer design development from feasibility concept to baseline design

The Maunakea Spectroscopic Explorer is designed to be the largest non-ELT optical/NIR astronomical telescope, and will be a fully dedicated facility for multi-object spectroscopy over a broad range of spectral resolutions. The MSE design has progressed from feasibility concept into its current baseline design where the system configuration of main systems such as telescope, enclosure, summit facilities and instrument are fully defined. This paper will describe the engineering development of the main systems, and discuss the trade studies to determine the optimal telescope and multiplexing designs and how their findings are incorporated in the current baseline design.

Update report on FlyEyes: a dual CCD detector system upgrade for PUEO

CFHT is planning to upgrade its adaptive optics system, PUEO, to a high order system with 104 elements, PUEO NUI. Currently PUEO uses a 19 element deformable mirror with the equivalent 19 avalanche photodiode (APD) detectors as its curvature wavefront sensor. PUEO NUI plans to implement the curvature wavefront sensor using back illuminated CCID-35 detectors developed by J. Beletic et al. instead of 104 APDs, which are prohibitively expensive under the present budget conditions. The CCID-35 detectors, developed at ESO and MIT/LL, were specifically designed to serve as direct replacements for APDs in curvature sensing. The first step in the upgrade is to build and test a system using two CCID-35 detectors, dubbed FlyEyes. These new detectors were successfully tested and integrated in the lab by R. Dorn at ESO but have yet to see sky time. FlyEyes will be their first opportunity. They will directly replace the 19 APDs in PUEO temporarily for a few engineering nights in January of 2005.

VASAO: visible all sky adaptive optics: a new adaptive optics concept for CFHT

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 [4]) 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.

FlyEyes: integrating CCID-35 into PUEO AO system at CFHT

A project to upgrade PUEO, the CFHT AO system, was first proposed in 2002. As part of the upgrade effort, a technology project was conceived to evaluate and characterize the backside-illuminated CCID-35 detector as suitable a replacement for the array of avalanche photo diode modules (APDs) in the curvature wavefront sensor. The CCID-35 was envisioned to replace an array of expensive APDs thus providing a cost-effective means of upgrading PUEO to a higher-order system. Work on the project, dubbed FlyEyes, occurred sporadically until Oct 2005 but substantial progress has been made since. This paper was intended to report on the performance of FlyEyes in PUEO but unfortunately the instrument was not ready for tests at the time of this writing. This paper summarizes the progress made on the project thus far and touches upon some of the difficulties encountered.

On-sky results with the fast guiding system on the SPIRou spectroplarimeter at CFHT

SPIRou (SpectroPolarimètre Infra-Rouge in French), is a near-infrared, fiber-fed spectropolarimeter at the CanadaFrance-Hawaii Telescope (CFHT) which gives full spectral coverage from 0.98 to 2.35 μm with a resolving power of 70,000. The main science drivers for SPIRou are (i) detecting and characterizing exoplanets around nearby M dwarfs through high-precision (1 m/s) velocimetry, and (ii) investigating the impact of magnetic fields on star/planet formation through spectropolarimetry. One of the requirements for achieving this challenging radial velocity (RV) precision is ensuring that the observed star does not move with respect to the instrument entrance aperture by more than 0.05 arcseconds RMS over the course of the observation. This is complicated by the fact that the guiding uses light from the science target so that only about 13% of the light (10% from the wings and 3% from the core) is available in seeing conditions of 0.65 arc-seconds in H band. To achieve this level of guiding accuracy, a fast guiding system has been implemented in the injection module of the instrument. This paper describes the system, its performance in tests on the sky with the CFHT since the delivery of SPIRou in January 2018, and gives comparisons to laboratory measurements and simulations.

Expected observing efficiency of the Maunakea Spectroscopic Explorer (MSE)

The Maunakea Spectroscopic Explorer (MSE) will obtain millions of spectra each year in the optical to near-infrared, at low (R ≃ 3; 000) to high (R ≃ 40; 000) spectral resolution by observing <4,000 spectra per pointing via a highly multiplexed fiber-fed system. Key science programs for MSE include black hole reverberation mapping, stellar population analysis of faint galaxies at high redshift, and sub-km/s velocity accuracy for stellar astrophysics. One key metric of the success of MSE will be its survey speed, i.e. how many spectra of good signal-to-noise ratio will MSE be able to obtain every night and every year. This is defined at the higher level by the observing efficiency of the observatory and should be at least 80%, as indicated in the Science Requirements. In this paper we present the observing efficiency budget developed for MSE based on historical data at the Canada-France-Hawaii Telescope and other Maunakea Observatories. We describe the typical sequence of events at night to help us compute the observing efficiency and how we envision to optimize it to meet the science requirements

MegaCam FAST: reducing data acquisition time on the Canada-France-Hawaii Telescope’s wide-field optical imager

MegaCam is Canada-France-Hawaii Telescope’s (CFHT) one-degree wide-field optical imager with an array of 40 CCDs that has been in operation since 2003 and remains the most demanded instrument at CFHT with an oversubscription of 2.5 each semester. Large programs requiring hundreds of nights dominate the available observing time leaving little for PI programs. To accommodate the demand and to improve overall observing efficiency, we launched the MegaCam FAST project to reduce the data acquisition time.

Observatory software for the Maunakea Spectroscopic Explorer

The Canada-France-Hawaii Telescope is currently in the conceptual design phase to redevelop its facility into the new Maunakea Spectroscopic Explorer (MSE). MSE is designed to be the largest non-ELT optical/NIR astronomical telescope, and will be a fully dedicated facility for multi-object spectroscopy over a broad range of spectral resolutions. This paper outlines the software and control architecture envisioned for the new facility. The architecture will be designed around much of the existing software infrastructure currently used at CFHT as well as the latest proven opensource software. CFHT plans to minimize risk and development time by leveraging existing technology.

The upgraded telescope control system performance for the Canada-France-Hawaii Telescope

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.

Dome shutter failure causes longest shutdown (67-nights) ever recorded by CFHT Observatory

The dome shutter drive system for the CFHT observatory experienced two, separate, catastrophic failures recently (15 DEC 11) and (14 APR 12); leading to a full-blown, company-wide investigation to understand and determine the root cause of both failures. Multiple resources were utilized to detect and reveal clues to help determine the cause of failure. Former colleagues were consulted, video footage investigated, ammeter plots dissected, solid models developed, forensic analysis of failed parts performed, controller mock-up established; all in an attempt to gather data, better understand the system, and develop a clear path solution to resurrect the shutter and return it to normal operation. My paper will attempt to describe in detail the problems encountered, investigations performed, analysis developed, and solutions integrated.