A well-adapted visible and infrared spectrograph has been developed for the SNAP (SuperNova/Acceleration Probe) experiment proposed for JDEM. The primary goal of this instrument is to ensure the control of Type Ia supernovae. The spectrograph is also a key element for calibration and is able to measure redshift of some thousands of galaxy spectra both in visible and IR.
An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is presented. We present the current design and expected performances. We show that with the current optimization and the proposed technology, we expect the most sensitive instrument proposed on this kind of mission. We recall the readiness of the concept and of the slicer technology thanks to large prototyping efforts performed in France which validate the proposition. This work is supported in France by CNRS/INSU, CNRS/IN2P3 and by the French spatial agency (CNES).
The readout noise of a H2RG HgCdTe NIR detector from Teledyne is measured at a temperature T=100K.
In a previous work, we have analysed the evolution of the readout noise as a function of the number of reads
in terms of the frequency power spectrum of the noise with our in-house hybrid readout electronics. The new
measurements with the SIDECAR ASIC provided by Teledyne Imaging Sensors are compared to the previous
ones. The noise power spectrum found can be used in a wide range of timing conditions and allows to predict
the 1/f effects.
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.
The readout noise of a H2RG HgCdTe NIR detector from Teledyne is measured at a temperature T=110K.
It is shown that a Fowler mode with n = 240 allows to reach a noise of 2.63e (single read). A description of
the power spectrum in terms of 3 parameters reproduces the variation of the noise as a function the number
of Fowler samples, as well as its dependence on the periodicity of the sampling. The variance of the noise
decreases with frequency with an effective power of 0.62 in our measurement domain. The behaviour of the
detector under different experimental conditions can then be predicted.
A visible and infrared spectrograph based on integral field method (IFU) using the slicer technology is proposed
for the SNAP(SuperNovae/Acceleration Probe) mission. The spectrograph is a key element to control supernovae
Type Ia measurements and to calibrate standards stars at the per cent level. The current concept has a low
spectral resolution (about 100) and is under-sampled in the infrared arm. A demonstrator has been manufactured
and is used to validate the performances. The calibration procedure has been developed using a full simulation
of the instrument at the pixel level and tested with the demonstrator. We present the first experimental results
performed in the visible range and we compare them with the results predicted by the simulation.
A well-adapted visible and infrared spectrograph has been developed for the SNAP (SuperNova/Acceleration Probe)
experiment proposed for JDEM. The primary goal of this instrument is to ensure the control of Type Ia supernovae. The
spectrograph is also a key element for calibration and is able to measure redshift of some thousands of galaxy spectra
both in visible and IR.
An instrument based on an integral field method with the powerful concept of imager slicing has been designed and is
presented. We present the current design and expected performances. We show that with the current optimization and
the proposed technology, we expect the most sensitive instrument proposed on this kind of mission. We recall the
readiness of the concept and of the slicer technology thanks to large prototyping efforts performed in France which
validate the proposition. This work is supported in France by CNRS/INSU, CNRS/IN2P3 and by the French spatial
agency (CNES).
An integral field spectrograph concept has been developed for the SNAP/JDEM(SuperNova/Acceleration Probe)
experiment. This spectrograph will be optimized for faint supernovae and galaxies in a 3×6 arsec2 at low spectral
resolution (R~100) through the wavelength range (0.35-1.7 μm). The integral field method is based on glass
image slicer. A prototype of this instrument has been build to validate the concept and prove the optical and
functional requirements of the SNAP spectrograph.
In this paper, we present the first results of this demonstrator. We describe the demonstrator philosophy, set
up and functional performances. We present then the first experimental results obtained in the visible range.
We validate the slicer optical quality through a set of measurements: PSF, optical losses.
A well-adapted spectrograph concept has been developed for the SNAP (SuperNova/Acceleration Probe) experiment.
The goal is to ensure proper identification of Type Ia supernovae and to standardize the magnitude of each candidate by
determining explosion parameters. The spectrograph is also a key element for the calibration of the science mission. An
instrument based on an integral field method with the powerful concept of imager slicing has been designed and is
presented in this paper. The spectrograph concept is optimized to have high efficiency and low spectral resolution
(R~100), constant through the wavelength range (0.35-1.7μm), adapted to the scientific goals of the mission.
A dedicated optimized spectrograph based on an integral field unit adopting an imager slicing concept has been
developed for the SNAP (SuperNova/Acceleration Probe) experiment. A prototype for the SNAP application is
undergoing test at Marseille (France) between LAM (INSU) and CPPM/IPNL(IN2P3) to provide the verification of the
optical performances associated with the development of a complete simulation of the instrument. The goal of this
demonstrator is to prove the optical and functional requirements of the SNAP spectrograph: diffraction losses, spectrophotometric
calibration, image quality and straylight.
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