Frank Grupp

The 4MOST instrument concept overview

The 4MOST[1] instrument is a concept for a wide-field, fibre-fed high multiplex spectroscopic instrument facility on the ESO VISTA telescope designed to perform a massive (initially >25x106 spectra in 5 years) combined all-sky public survey. The main science drivers are: Gaia follow up of chemo-dynamical structure of the Milky Way, stellar radial velocities, parameters and abundances, chemical tagging; eROSITA follow up of cosmology with x-ray clusters of galaxies, X-ray AGN/galaxy evolution to z~5, Galactic X-ray sources and resolving the Galactic edge; Euclid/LSST/SKA and other survey follow up of Dark Energy, Galaxy evolution and transients. The surveys will be undertaken simultaneously requiring: highly advanced targeting and scheduling software, also comprehensive data reduction and analysis tools to produce high-level data products. The instrument will allow simultaneous observations of ~1600 targets at R~5,000 from 390-900nm and ~800 targets at R<18,000 in three channels between ~395-675nm (channel bandwidth: 45nm blue, 57nm green and 69nm red) over a hexagonal field of view of ~ 4.1 degrees. The initial 5-year 4MOST survey is currently expect to start in 2020. We provide and overview of the 4MOST systems: optomechanical, control, data management and operations concepts; and initial performance estimates.

New extended atomic data in cool star model atmospheres Using Kurucz's new iron data in MAFAGS-OS models

Context. Cool star model atmospheres are a common tool for the investigation of stellar masses, ages and elemental abundance composition. Theoretical atmospheric models strongly depend on the atomic data used when calculating them. Aims. We present the changes in flux and temperature stratification when changing from iron data computed by R.L. Kurucz in the mid 90s to the Kurucz 2009 iron computations. Methods. MAFAGS-OS opacity sampling atmospheres were recomputed with Kurucz 2009 iron atomic data as implemented in the VALD database by Ryabchikova. Temperature stratification and emergent flux distribution of the new version, called MAFAGS-OS9, is compared to the former version and to solar flux measurements. Results. Using the Kurucz line lists converted into the VALD format and new bound-free opacities for Mg i and Al i leads to changes in the solar temperature stratification by not more than 28 K. At the same time, the calculated solar flux distribution shows significantly better agreement between observations and theoretical solar models. These changes in the temperature stratification of the corresponding models are small, but nevertheless of a magnitude that affects stellar parameter determinations and abundance analysis.

CAFE: Calar Alto Fiber-fed Échelle spectrograph

We present here CAFE, the Calar Alto Fiber-fed Echelle spectrograph, a new instrument built at the Centro Astronomico Hispano Aleman (CAHA). CAFE is a single-fiber, high-resolution (R ∼ 70 000) spectrograph, covering the wavelength range between 3650−9800 A. It was built on the basis of the common design for Echelle spectrographs. Its main aim is to measure radial velocities of stellar objects up to V ∼ 13−14 mag with a precision as good as a few tens of m s −1 . To achieve this goal the design was simplified at maximum, removing all possible movable components, the central wavelength is fixed, as is the wavelength coverage; there is no filter wheel, etc. Particular care was taken with the thermal and mechanical stability. The instrument is fully operational and publically accessible at the 2.2 m telescope of the Calar Alto Observatory. In this article we describe (i) the design, summarizing its manufacturing phase; (ii) characterize the main properties of the instrument; (iii) describe the reduction pipeline; and (iv) show the results from the first light and commissioning runs. The preliminar results indicate that the instrument fulfills the specifications and can achieve the planned goals. In particular, the results show that the instrument is more efficient than anticipated, reaching a signalto-noise of ∼20 for a stellar object as faint as V ∼ 14. 5m ag in∼2700 s integration time. The instrument is a wonderful machine for exoplanetary research (by studying large samples of possible systems cotaining massive planets), galactic dynamics (highly precise radial velocities in moving groups or stellar associations), or astrochemistry.

MICADO: first light imager for the E-ELT

MICADO will equip the E-ELT with a first light capability for diffraction limited imaging at near-infrared wavelengths. The instrument’s observing modes focus on various flavours of imaging, including astrometric, high contrast, and time resolved. There is also a single object spectroscopic mode optimised for wavelength coverage at moderately high resolution. This contribution provides an overview of the key functionality of the instrument, outlining the scientific rationale for its observing modes. The interface between MICADO and the adaptive optics system MAORY that feeds it is summarised. The design of the instrument is discussed, focusing on the optics and mechanisms inside the cryostat, together with a brief overview of the other key sub-systems.MICADO will be the first-light wide-field imager for the European Extremely Large Telescope (E-ELT) and will provide difiraction limited imaging (7mas at 1.2mm) over a ~53 arcsecond field of view. In order to support various consortium activities we have developed a first version of SimCADO: an instrument simulator for MICADO. SimCADO uses the results of the detailed simulation efforts conducted for each of the separate consortium-internal work packages in order to generate a model of the optical path from source to detector readout. SimCADO is thus a tool to provide scientific context to both the science and instrument development teams who are ultimately responsible for the final design and future capabilities of the MICADO instrument. Here we present an overview of the inner workings of SimCADO and outline our plan for its further development.

MICADO: the E-ELT adaptive optics imaging camera

MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (~1 arcmin) field of view. For initial operations, it can also be used with its own simpler AO module that provides on-axis diffraction limited performance using natural guide stars. We discuss the instruments key capabilities and expected performance, and show how the science drivers have shaped its design. We outline the technical concept, from the opto-mechanical design to operations and data processing. We describe the AO module, summarise the instrument performance, and indicate some possible future developments.

VIRUS-W: an integral field unit spectrograph dedicated to the study of spiral galaxy bulges

We present the design, layout and performance estimates for a fiber based Integral Field Unit spectrograph. This instrument is built for flexible use at different telescopes, and in particular for the new 2m telescope on Mount Wendelstein in the Bavarian Alps. Based on the VIRUS spectrograph for the HETDEX experiment, the proposed instrument will have a fiber head consisting of 267 optical fibers. The large angular field of view of 150×75 arcseconds will allow full coverage of the bulge regions of most local late type galaxies in one or two pointings. Realized by the usage of VPH gratings, a R ≈ 2500 and a R ≈ 6800 mode with 850Å and 515Å wavelength coverage will be dedicated to the study of stellar populations and kinematics of late type galaxy bulges.

Euclid near-infrared spectrophotometer instrument concept at the end of the phase A study

The Euclid mission objective is to map the geometry of the dark Universe by investigating the distance-redshift relationship and the evolution of cosmic structures. The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments operating in the near-IR spectral region (0.9-2μm). The instrument is composed of: - a cold (140K) optomechanical subsystem constituted by a SiC structure, an optical assembly, a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control - a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG 2.4μm. The detection subsystem is mounted on the optomechanical subsystem structure - a warm electronic subsystem (280K) composed of a data processing / detector control unit and of an instrument control unit. This presentation will describe the architecture of the instrument, the expected performance and the technological key challenges. This paper is presented on behalf of the Euclid Consortium.

Relative stability of two laser frequency combs for routine operation on HARPS and FOCES

We report on the installation of a laser frequency comb (LFC) at the HARPS spectrograph, which we characterize relative to a second LFC that we had brought to HARPS for testing. This allowed us for the first time to probe the relative stability of two independent astronomical LFCs over an extended wavelength range. Both LFCs covered the spectral range of HARPS at least from 460 to 690 nm. After optimization of the fiber coupling to HARPS to suppress modal noise, a relative stability of the two LFCs in the low cm/s range was obtained. In combination with the results of our four earlier LFC test campaigns on HARPS, the available data now cover a time span of more than six years.

First tests of the compact low scattered-light 2m-Wendelstein Fraunhofer Telescope

The integration of the 2m Fraunhofer telescope started in August 2011 at the Mt. Wendelstein observatory. The logistics of the project are a key problem of the integration as the observatory has no road access. All large or heavy components inlcuding the primary mirror were successfully delivered by helicopter. Meanwhile, they are integrated in the telescope. The special design features of this alt-az telescope are its compactness and the low-ghost wide field optics (0.7 deg. f.o.v. diameter). We will briefly report on tests of the building and of the telescope system before the telescope moved to the mountain. The integration at the observatory and the first astronomical performances tests of the telescopes are discussed, and a brief update on the status of its instruments is presented. We comment on the cleaning and recoating strategy for the primary mirror based on sample tests.

Ground-based and Airborne Instrumentation for Astronomy III

MICADO is the adaptive optics imaging camera for the E-ELT. It has been designed and optimised to be mounted to the LGS-MCAO system MAORY, and will provide diffraction limited imaging over a wide (~1 arcmin) field of view. For initial operations, it can also be used with its own simpler AO module that provides on-axis diffraction limited performance using natural guide stars. We discuss the instruments key capabilities and expected performance, and show how the science drivers have shaped its design. We outline the technical concept, from the opto-mechanical design to operations and data processing. We describe the AO module, summarise the instrument performance, and indicate some possible future developments.