KEYWORDS: Calibration, Visualization, Data processing, James Webb Space Telescope, Algorithm development, Sensors, Data analysis, Cryogenics, Spectrographs, Molybdenum
The future James Webb Space Telescope (JWST), developed jointly by the American, European and Canadian
space agencies (NASA, ESA and CSA), is scheduled for launch in 2013. The near-infrared spectrograph NIRSpec
will be a major element of its instrument suite and is built by EADS Astrium for ESA. NIRSpec is a multiobject
spectrograph allowing astronomers to obtain the spectra of more than one hundred objects in a single
exposure. NIRSpec is currently under construction and, when finished, will be subjected to a stringent onground
test campaign to verify its performance. These tests are conducted in collaboration with ESA. A rapid
and reliable system to handle and analyse the data is crucial in this phase as the time available to run the
cryogenic tests is limited. To facilitate this process we are developing a toolbox of dedicated algorithms and
interactive visualisation modules. These standalone modules form the basis of the Instrument Quick Look
Analysis and Calibration (IQLAC) software. Individual workflows, optimized for specific tests, can then be
generated efficiently using this toolbox. Furthermore, this set of dedicated algorithms will provide a reference
frame for the development of the operational data processing software by ESA.
The Multi-Unit Spectroscopic Explorer (MUSE) is an integral-field spectrograph for the VLT for the next decade. Using
an innovative field-splitting and slicing design, combined with an assembly of 24 spectrographs, MUSE will provide
some 90,000 spectra in one exposure, which cover a simultaneous spectral range from 465 to 930nm. The design and
manufacture of the Calibration Unit, the alignment tests of the Spectrograph and Detector sub-systems, and the
development of the Data Reduction Software for MUSE are work-packages under the responsibility of the AIP, who is a
partner in a European-wide consortium of 6 institutes and ESO, that is led by the Centre de Recherche Astronomique de
Lyon. MUSE will be operated and therefore has to be calibrated in a variety of modes, which include seeing-limited and
AO-assisted operations, providing a wide and narrow-field-of-view. MUSE aims to obtain unprecedented ultra-deep 3D-spectroscopic
exposures, involving integration times of the order of 80 hours at the VLT. To achieve the corresponding
science goals, instrumental stability, accurate calibration and adequate data reduction tools are needed. The paper
describes the status at PDR of the AIP related work-packages, in particular with respect to the spatial, spectral, image
quality, and geometrical calibration and related data reduction aspects.
The Multi Unit Spectroscopic Explorer (MUSE) is a second-generation VLT panoramic integral-field spectrograph under preliminary design study. MUSE has a field of 1x1 arcmin2 sampled at 0.2x0.2 arcsec2 and is assisted by the VLT ground layer adaptive optics ESO facility using four laser guide stars. The simultaneous spectral range is 0.465-0.93 μm, at a resolution of R~3000. MUSE couples the discovery potential of a large imaging device to the measuring capabilities of a high-quality spectrograph, while taking advantage of the increased spatial resolution provided by adaptive optics. This makes MUSE a unique and tremendously powerful instrument for discovering and characterizing objects that lie beyond the reach of even the deepest imaging surveys. MUSE has also a high spatial resolution mode with 7.5x7.5 arcsec2 field of view sampled at 25 milli-arcsec. In this mode MUSE should be able to obtain diffraction limited data-cubes in the 0.6-0.93 μm wavelength range. Although the MUSE design has been optimized for the study of galaxy formation and evolution, it has a wide range of possible applications; e.g. monitoring of outer planets atmosphere, environment of young stellar objects, super massive black holes and active nuclei in nearby galaxies or massive spectroscopic surveys of stellar fields in the Milky Way and nearby galaxies.
KEYWORDS: Galactic astronomy, Stars, Space telescopes, Hubble Space Telescope, Spectroscopy, Charge-coupled devices, Signal to noise ratio, Spectrographs, Absorption, Statistical analysis
We discuss first results from a spectroscopic survey of nuclear star clusters in nearby, late-type spiral galaxies. The data, obtained with the Space Telescope Imaging Spectrograph (STIS), allow us to derive cluster ages via stellar population synthesis methods. We present some typical data sets, describe the fitting algorithm, and discuss the results for the 6 objects studied so far. We find that only one nuclear cluster spectrum is dominated by a population older than 1 Gyr. In all cases, the fit is significantly improved by allowing for multiple generations of stars. Although preliminary, these results support the notion that nuclear cluster formation is most likely a repetitive process.
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