Martin Landriau

Regrowth of stellar discs in mature galaxies: the two-component nature of NGC 7217 revisited with VIRUS-W

Previous studies have reported the existence of two counter-rotating stellar disks in the early-type spiral galaxy NGC7217. We have obtained high-resolution optical spectroscopic data (R ~ 9000) with the new fiber-based Integral Field Unit instrument VIRUS-W at the 2.7m telescope of the McDonald Observatory in Texas. Our analysis confirms the existence of two components. However, we find them to be co-rotating. The first component is the more luminous (~ 77% of the total light), has the higher velocity dispersion (~ 170 km/s) and rotates relatively slowly (projected

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

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Deployment of the Hobby-Eberly Telescope wide field upgrade

= 50 km/s). The lower luminosity second component, (~ 23% of the total light), has a low velocity dispersion (~ 20 km/s) and rotates quickly (projected

The construction, alignment, and installation of the VIRUS spectrograph

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Design, alignment, and deployment of the Hobby Eberly Telescope prime focus instrument package

= 150 km/s). The difference in the kinematics of the two stellar components allows us to perform a kinematic decomposition and to measure the strengths of their Mg and Fe Lick indices separately. The rotational velocities and dispersions of the less luminous and faster component are very similar to those of the interstellar gas as measured from the [OIII] emission. Morphological evidence of active star formation in this component further suggests that NGC7217 may be in the process of (re)growing a disk inside a more massive and higher dispersion stellar halo. The kinematically cold and regular structure of the gas disk in combination with the central almost dust-free morphology allows us to compare the dynamical mass inside of the central 500pc with predictions from a stellar population analysis. We find agreement between the two if a Kroupa stellar initial mass function is assumed.

Laboratory performance testing, installation, and commissioning of the wide field upgrade tracker for the 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.

VIRUS early installation and commissioning

The Hobby-Eberly Telescope (HET) is an innovative large telescope located in West Texas at the McDonald Observatory. The HET operates with a fixed segmented primary and has a tracker, which moves the four-mirror optical 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 substantially increase the pupil size to 10 meters (from 9.2 m) and the field of view to 22 arcminutes (from 4 arcminutes) by replacing the corrector, tracker, and prime focus instrument package. In addition to supporting existing instruments, and a new low resolution spectrograph, this wide field upgrade will feed a revolutionary new integral field spectrograph called VIRUS, in support of the Hobby-Eberly Telescope Dark Energy Experiment (HETDEX§). The upgrade is being installed and this paper discusses the current status.

A control system framework for the Hobby-Eberly telescope

VIRUS is the massively replicated fiber-fed spectrograph being built for the Hobby-Eberly Telescope to support HETDEX (the Hobby-Eberly Telescope Dark Energy Experiment). The instrument consists of 156 identical channels, fed by 34,944 fibers contained in 78 integral field units, deployed in the 22 arcminute field of the upgraded HET. VIRUS covers 350-550nm at R ≈ 700 and is built to target Lyman α emitters at 1.9 < z < 3.5 to measure the evolution of dark energy. Here we present the assembly line construction of the VIRUS spectrographs, including their alignment and plans for characterization. We briefly discuss plans for installation on the telescope. The spectrographs are being installed on the HET in several stages, and the instrument is due for completion by the end of 2014.

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

The Hobby-Eberly Telescope (HET) is undergoing an upgrade to increase the field of view to 22 arc-minutes with the dark energy survey HETDEX the initial science goal [1]. Here we report on the design, alignment, and deployment of a suite of instruments located at prime focus of the upgraded HET. This paper reviews the integration of motion control electronics and software and alignment of those electromechanical systems. Use of laser trackers, alignment telescopes, and other optical alignment techniques are covered. Deployment onto the upgraded telescope is discussed.

Regrowth of stellar disks in mature galaxies: The two component nature of NGC 7217 revisited with VIRUS-W

A major upgrade of the HET is in process that increases the pupil size to 10 meters and the field of view to 22’ by replacing the four-mirror corrector and prime focus instrument package to track the sidereal and non-sidereal motions of astronomical targets. To support the new payload a new Tracker, comprising 13 axes, and weighing 20 tons, was designed, built and tested at the University of Texas Center for Electromechanics, in Austin, Texas. It was then disassembled and installed on the HET. Structural modifications were performed on the upper hexagon of the telescope structure to support the net increase of 15% to the total mass of the system and maintain fundamental mode performance of 5Hz. Testing in the laboratory, as well as subsequent commissioning tests on the HET, confirm that the Tracker will position the payload to acquire and track within the specified +/-9.5um de-center, +/-15um de-focus, and +/-4.4 arc-sec tip/tilt requirement*.