SPHERE is an instrument aimed to the search for low mass companions around young stars in the solar neighborhood. To achieve this goal light from the host star (and in particular the speckle pattern due to the telescope aberrations) should be strongly attenuated while avoiding to cancel out the light from the faint companion. Different techniques can be used to fulfill this aim exploiting the multi-wavelength datacube produced by the Integral Field Spectrograph that is one of the scientific modules that composes SPHERE. In particular we have tested the application of the Spectral Deconvolution and of the Principal Components Analysis techniques. Both of them allow us to obtained a contrast better than 10−5 with respect to the central star at separations of the order of 0.4 arcsec. A further improvement of one order of magnitude can be obtained by combining one of these techniques to the Angular Differential Imaging. To investigate the expected performance of IFS in characterizing detected objects we injected in laboratory data synthetics planets with different intrinsic fluxes and projected separations from the host star. We performed a complete astrometric and photometric analysis of these images to evaluate the expected errors on these measurements, the spectral fidelity and the differences between the reduction methods. The main issue is to avoid the strong self-cancellation that is inherent to all the reduction methods. We have in particular tested two possible solutions: the use of a mask during the reduction on the positions of the companions or, alternatively, using a KLIP procedure for the IFS. This latter seems to give better results in respect o the classical PCA, allowing us to obtain a good spectral reconstruction for simulated objects down to a contrast of ~10-5.
Direct imaging of exoplanet is one of the most exciting field of planetology today. The light coming from exoplanet orbiting their host star witnesses for the chemical composition of the atmosphere, and the potential biomarkers for life. However, the faint flux to be imaged, very close to the huge flux of the parent star, makes this kind of observation extremely difficult to perform from the ground. The direct imaging instruments (SPHERE [1], GPI [2]) are nowaday reaching lab maturity. Such instrument imply the coordination of XAO for atmospherical turbulence real-time correction, coronagraphy for star light extinction, IR Dual band camera, IFS, and visible polarimetry. The imaging modes include single and double difference (spectral and angular). The SPHERE project is now at the end of AIT phase. This paper presents the very last results obtained in laboratory, with realistic working conditions. These AIT results allows one to predict on-sky performance, that should come within the next weeks after re-installation at Very Large Telescope at Paranal.
SPHERE (Spectro-Polarimetric High-contrast Exoplanet Research) is a second generation
instrument for the VLT optimized for very high-contrast imaging around bright stars. Its primary
science goal is the detection and characterization of giant planets, together with observation of
circumstellar environment. The infrared differential imager and spectrograph (IRDIS), one of the
three science instruments for SPHERE, provides simultaneous differential imaging in the near
infrared, among with long slit spectroscopy, classical imaging and infrared polarimetry. IRDIS is
designed to achieve very high contrast with the help of extreme-AO (Strehl < 90%), coronography,
exceptional image quality (including non-common-path aberrations compensation), very accurate
calibration strategies and very advanced data processing for speckle suppression. In this paper, we
report on the latest experimental characterizations of IRDIS performed with SPHERE/SAXO before
the preliminary acceptance in Europe.
The work of astronomers is getting more complex and advanced as the progress of computer development occurs.
With improved computing capabilities and increased data flow, more sophisticated software is required in order
to interpret, and fully exploit, astronomic data. However, it is not possible for every astronomer to also be a
software specialist. As history has shown, the work of scientists always becomes increasingly specialised, and
we here argue in favour of another, at least partial, split between "programmers" and "interpreters". In this
presentation we outline our vision for a new approach and symbiosis between software specialists and scientists,
and present its advantages along with a simple test case.
The Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument for the VLT is designed for
discovering new giant planets orbiting nearby stars by direct imaging. The accuracy demands on this complex
instrument and its data reduction handling are high. Here, we outline the design of the data reduction software
for SPHERE and argue that SPHERE can be seen as one of the first of a new generation of instruments. We
discuss what can be learned from SPHERE about new challenges in reduction software design, management
and development. Along with the key issues, we formulate some general principles to help overcoming these
challenges.
The Spectro-Polarimetric High-contrast Exoplanet Research (SPHERE) instrument for the VLT is designed for
discovering and studying new extra-solar giant planets orbiting nearby stars by direct imaging. In this paper, we describe
the philosophy behind the SPHERE baseline data processing sequences dealing with calibration observations, and how
these can affect the reduction of subsequent calibrations and scientific data. Additionally, we present the result of our
detector simulations and the first tests of data reduction recipe prototypes.
The SPHERE project is a ESO second generation instrument which aims to detect giant extra-solar planets in the vicinity of
bright stars and to characterise the objects found through spectroscopic and polarimetric observations.Technical tolerances
are the tightest ever for an instrument installed at the VLT, and SPHERE demands a rather unique DRH software package to
accompany the data from the observation preparation to the search for planetary signals. This paper addresses the current
status of the data reduction and handling system (DRHS) for the SPHERE instruments. It includes descriptions of the
calibration and science data, reduction steps and their data products. The development strategy for creating of a coherent
software that allows to achieve high observation efficiency is briefly discussed.
The 2nd generation VLT instrument SPHERE will include an integral field spectrograph to enhance the capabilities
of detection of planetary companions close to bright stars. SPHERE-IFS is foreseen to work in near
IR (0.95-1.65 micron) at low spectral resolution. This paper describes the observing strategies, the adopted
hardware solutions for calibrating the instrument, and the data reduction procedures that are mandatory for the
achievement of the extreme contrast performances for which the instrument is designed.
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