John M. Good

Early performance and present status of the Hobby-Eberly Telescope

The Hobby-Eberly telescope (HET) is a recently completed 9- meter telescope designed to specialize in spectroscopy. It saw first light in December 1996 and during July 1997, it underwent its first end-to-end testing acquiring its first spectra of target objects. We review the basic design of the HET. In addition we summarize the performance of the telescope used with a commissioning spherical aberration correlator and spectrograph, the status of science operations and plans for the implementation of the final spherical aberration corrector and facility class instruments.

VIRUS: a massively replicated 33k fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of a baseline build of 150 identical spectrographs (arrayed as 75 units, each with a pair of spectrographs) fed by 33,600 fibers, each 1.5 arcsec diameter, deployed over the 22 arcminute field of the upgraded 10 m Hobby-Eberly Telescope (HET). The goal is to deploy 96 units. VIRUS has a fixed bandpass of 350-550 nm and resolving power R~700. VIRUS is the first example of industrial-scale replication applied to optical astronomy and is capable of spectral surveys of large areas of sky. The method of industrial replication, in which a relatively simple, inexpensive, unit spectrograph is copied in large numbers, offers significant savings of engineering effort, cost, and schedule when compared to traditional instruments. The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX+) using 0.8M Lyman-α emitting galaxies as tracers. The full VIRUS array is due to be deployed in late 2011 and will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope. VIRUS and HET will open up wide field surveys of the emission-line universe for the first time. We present the design, cost, and current status of VIRUS as it enters production, and review performance results from the VIRUS prototype. We also present lessons learned from our experience designing for volume production and look forward to the application of the VIRUS concept on future extremely large telescopes (ELTs).

Current status of the Hobby-Eberly Telescope wide-field upgrade

The Hobby-Eberly Telescope (HET) is an innovative large telescope of 9.2 meter aperture, located in West Texas at the McDonald Observatory (MDO). The HET operates with a fixed segmented primary and has a tracker which moves the four-mirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of objects. A major upgrade of the HET is in progress that will increase the pupil size to 10 meters and the field of view to 22′ by replacing the corrector, tracker and prime focus instrument package. In addition to supporting the existing suite of instruments, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEXχ). This paper discusses the current status of this upgrade.

The First Hobby-Eberly Telescope Planet: A Companion to HD 37605

We report the first detection of a planetary-mass companion to a star using the High Resolution Spectrograph (HRS) of the Hobby-Eberly Telescope (HET). The HET-HRS now gives routine radial velocity precision of 2-3 m/s for high SNR observations of quiescent stars. The planetary-mass companion to the metal-rich K0V star HD37605 has an orbital period of 54.23 days, an orbital eccentricity of 0.737, and a minimum mass of 2.84 Jupiter masses. The queue-scheduled operation of the Hobby-Eberly Telescope enabled us to discovery of this relatively short-period planet with a total observation time span of just two orbital periods. The ability of queue-scheduled large-aperture telescopes to respond quickly to interesting and important results demonstrates the power of this new approach in searching for extra-solar planets as well as in other ares of research requiring rapid response time critical observations.We report the first detection of a planetary-mass companion to a star using the High Resolution Spectrograph (HRS) of the Hobby-Eberly Telescope (HET). The HET HRS now gives routine radial velocity precision of 2-3 m s-1 for high signal-to-noise ratio observations of quiescent stars. The planetary-mass companion to the metal-rich K0 V star HD 37605 has an orbital period of 54.23 days, an orbital eccentricity of 0.737, and a minimum mass of 2.84 Jupiter masses. The queue-scheduled operation of the HET enabled us to discover this relatively short period planet with a total observation time span of just two orbital periods. The ability of queue-scheduled large-aperture telescopes to respond quickly to interesting and important results demonstrates the power of this new approach in searching for extrasolar planets, as well as in other areas of research requiring rapid response time critical observations.

Development of a wide field spherical aberration corrector for the Hobby Eberly Telescope

A 4-mirror prime focus corrector is under development to provide seeing-limited images for the 10-m aperture Hobby- Eberly Telescope (HET) over a 22 arcminute wide field of view. The HET uses an 11-m fixed elevation segmented spherical primary mirror, with pointing and tracking performed by moving the prime focus instrument package (PFIP) such that it rotates about the virtual center of curvature of the spherical primary mirror. The images created by the spherical primary mirror are aberrated with 13 arcmin diameter point spread function. The University of Arizona is developing the 4-mirror wide field corrector to compensate the aberrations from the primary mirror and present seeing limited imaged to the pickoffs for the fiber-fed spectrographs. The requirements for this system pose several challenges, including optical fabrication of the aspheric mirrors, system alignment, and operational mechanical stability.

Design and development of a long-travel positioning actuator and tandem constant force actuator safety system for the Hobby Eberly Telescope wide-field upgrade

The Wide Field Upgrade presents a five-fold increase in mass for the Hobby-Eberly Telescopes* tracker system. The design of the Hobby-Eberly Telescope places the Prime Focus Instrument Package (PFIP) at a thirty-five degree angle from horizontal. The PFIP and its associated hardware have historically been positioned along this uphill axis (referred to as the telescopes Y-axis) by a single screw-type actuator. Several factors, including increased payload mass and design for minimal light obscuration, have led to the design of a new and novel configuration for the Y-axis screw-drive as part of the tracker system upgrade. Typical screw-drive designs in this load and travel class (approximately 50 kilonewtons traveling a distance of 4 meters) utilize a stationary screw with the payload translating with the moving nut component. The new configuration employs a stationary nut and translating roller screw affixed to the moving payload, resulting in a unique drive system design. Additionally, a second cable-actuated servo drive (adapted from a system currently in use on the Southern African Large Telescope) will operate in tandem with the screw-drive in order to significantly improve telescope safety through the presence of redundant load-bearing systems. Details of the mechanical design, analysis, and topology of each servo drive system are presented in this paper, along with discussion of the issues such a configuration presents in the areas of controls, operational and failure modes, and positioning accuracy. Findings and results from investigations of alternative telescope safety systems, including deformable crash barriers, are also included.

Mechanical design evolution of the VIRUS instrument for volume production and deployment

The Visible Integral-Field Replicable Unit Spectrograph (VIRUS) is an integral field spectrograph to support observations for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX). The VIRUS instrument is fed by more than 33,000 optical fibers and consists of 150 spectrographs in 75 individual, identical units. This paper discusses the evolution in mechanical design of the VIRUS unit spectrographs to maximize the cost benefit from volume production. Design features which enable volume manufacture and assembly are discussed. Strategies for reducing part count while enabling precision alignment are detailed. Design considerations for deployment, operation, and maintenance en mass at the Hobby-Eberly Telescope are also made. In addition, several enabling technologies are described including the use of cast aluminum in vacuum housings, use of cast Invar, and processing cast parts for precision tolerances.

VIRUS: production and deployment of a massively replicated fiber integral field spectrograph for the upgraded Hobby-Eberly Telescope

The Visible Integral-field Replicable Unit Spectrograph (VIRUS) consists of a baseline build of 150 identical spectrographs (arrayed as 75 unit pairs) fed by 33,600 fibers, each 1.5 arcsec diameter, at the focus of the upgraded 10 m Hobby-Eberly Telescope (HET). VIRUS has a fixed bandpass of 350-550 nm and resolving power R~700. VIRUS is the first example of industrial-scale replication applied to optical astronomy and is capable of surveying large areas of sky, spectrally. The VIRUS concept offers significant savings of engineering effort, cost, and schedule when compared to traditional instruments. The main motivator for VIRUS is to map the evolution of dark energy for the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX), using 0.8M Lyman-α emitting galaxies as tracers. The full VIRUS array is due to be deployed starting at the end of 2014 and will provide a powerful new facility instrument for the HET, well suited to the survey niche of the telescope, and will open up large area surveys of the emission line universe for the first time. VIRUS is in full production, and we are about half way through. We review the production design, lessons learned in reaching volume production, and preparation for deployment of this massive instrument. We also discuss the application of the replicated spectrograph concept to next generation instrumentation on ELTs.

Design and development of a high precision, high payload telescope dual drive system

A high precision, dual drive system has been designed and developed for the Wide Field Upgrade to the Hobby-Eberly Telescope* at McDonald Observatory in support of the Hobby-Eberly Telescope Dark Energy Experiment‡. Analysis, design and controls details will be of interest to designers of large scale, high precision robotic motion devices. The drive system positions the 19,000 kg star tracker to a precision of less than 5 microns along its 4-meter travel. While positioning requirements remain essentially equal to the existing HET, tracker mass increases by a factor greater than 5. The 10.5-meter long tracker is driven at each end by planetary roller screws, each having two distinct drive sources dictated by the desired operation: one slowly rotates the screw when tracking celestial objects and the second rotates the nut for rapid displacements. Key results of the roller screw rotordynamics analysis are presented. A description of the complex bearing arrangement providing required degrees of freedom as well as the impact of a detailed Failure Modes and Effects Analysis addressing necessary safety systems is also presented. Finite element analysis results demonstrate how mechanical springs increase the telescopes natural frequency response by 22 percent. The critical analysis and resulting design is provided.

The Hobby-Eberly Telescope: performance upgrades, status, and plans

The Hobby-Eberly Telescope (HET) is a fixed-elevation, 9.2-m telescope with a spherical primary mirror and a tracker at prime focus to follow astronomical objects. The telescope was constructed for