VIS: the visible imager for Euclid

Euclid-VIS is a large format visible imager for the ESA Euclid space mission in their Cosmic Vision program, scheduled for launch in 2019. Together with the near infrared imaging within the NISP instrument it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-900 nm over a field of view of ~0.5 deg2. By combining 4 exposures with a total of 2240 sec, VIS will reach to V=24.5 (10{\sigma}) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable point spread function (PSF) over a wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy imaging dataset with an unprecedented combination of spatial resolution, depth and area covering most of the extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Consortium during the Euclid Definition phase.Comment: 10 pages, 6 figure

Optical performance of the JWST MIRI flight model: characterization of the point spread function at high-resolution

The Mid Infra Red Instrument (MIRI) is one of the four instruments onboard the James Webb Space Telescope (JWST), providing imaging, coronagraphy and spectroscopy over the 5-28 microns band. To verify the optical performance of the instrument, extensive tests were performed at CEA on the flight model (FM) of the Mid-InfraRed IMager (MIRIM) at cryogenic temperatures and in the infrared. This paper reports on the point spread function (PSF) measurements at 5.6 microns, the shortest operating wavelength for imaging. At 5.6 microns the PSF is not Nyquist-sampled, so we use am original technique that combines a microscanning measurement strategy with a deconvolution algorithm to obtain an over-resolved MIRIM PSF. The microscanning consists in a sub-pixel scan of a point source on the focal plane. A data inversion method is used to reconstruct PSF images that are over-resolved by a factor of 7 compared to the native resolution of MIRI. We show that the FWHM of the high-resolution PSFs were 5-10% wider than that obtained with Zemax simulations. The main cause was identified as an out-of-specification tilt of the M4 mirror. After correction, two additional test campaigns were carried out, and we show that the shape of the PSF is conform to expectations. The FWHM of the PSFs are 0.18-0.20 arcsec, in agreement with simulations. 56.1-59.2% of the total encircled energy (normalized to a 5 arcsec radius) is contained within the first dark Airy ring, over the whole field of view. At longer wavelengths (7.7-25.5 microns), this percentage is 57-68%. MIRIM is thus compliant with the optical quality requirements. This characterization of the MIRIM PSF, as well as the deconvolution method presented here, are of particular importance, not only for the verification of the optical quality and the MIRI calibration, but also for scientific applications.Comment: 13 pages, submitted to SPIE Proceedings vol. 7731, Space Telescopes and Instrumentation 2010: Optical, Infrared, and Millimeter Wav

The Mid-Infrared Instrument for the James Webb Space Telescope, III: MIRIM, The MIRI Imager

In this article, we describe the MIRI Imager module (MIRIM), which provides broad-band imaging in the 5 - 27 microns wavelength range for the James Webb Space Telescope. The imager has a 0"11 pixel scale and a total unobstructed view of 74"x113". The remainder of its nominal 113"x113" field is occupied by the coronagraphs and the low resolution spectrometer. We present the instrument optical and mechanical design. We show that the test data, as measured during the test campaigns undertaken at CEA-Saclay, at the Rutherford Appleton Laboratory, and at the NASA Goddard Space Flight Center, indicate that the instrument complies with its design requirements and goals. We also discuss the operational requirements (multiple dithers and exposures) needed for optimal scientific utilization of the MIRIM.Comment: 29 pages, 9 figure

The Photodetector Array Camera and Spectrometer (PACS) on the Herschel Space Observatory

The Photodetector Array Camera and Spectrometer (PACS) is one of the three science instruments on ESA's far infrared and submillimetre observatory. It employs two Ge:Ga photoconductor arrays (stressed and unstressed) with 16x25 pixels, each, and two filled silicon bolometer arrays with 16x32 and 32x64 pixels, respectively, to perform integral-field spectroscopy and imaging photometry in the 60-210\mu\ m wavelength regime. In photometry mode, it simultaneously images two bands, 60-85\mu\ m or 85-125\mu\m and 125-210\mu\ m, over a field of view of ~1.75'x3.5', with close to Nyquist beam sampling in each band. In spectroscopy mode, it images a field of 47"x47", resolved into 5x5 pixels, with an instantaneous spectral coverage of ~1500km/s and a spectral resolution of ~175km/s. We summarise the design of the instrument, describe observing modes, calibration, and data analysis methods, and present our current assessment of the in-orbit performance of the instrument based on the Performance Verification tests. PACS is fully operational, and the achieved performance is close to or better than the pre-launch predictions

VIS: the visible imager for Euclid

Euclid-VIS is a large format visible imager under investigation for the ESA Euclid space mission in their Cosmic Vision program. Together with the near infrared photometer (NIP) it forms the basis of the weak lensing measurements of Euclid. VIS will image in a single r+i+z band from 550-920 nm over a field of view of ~0.5 deg2. Over 4 exposures totalling 1800 sec, VIS will reach to V=24.9 (10σ) for sources with extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep imaging with a tightly controlled and stable PSF over a wide surcey area of of 20000 deg2 to measure the cosmic shear from over 2 billion galaxies to high levels of accuracy, from which the cosmological parameters will be measured. In addition, VIS will also provide a legacy deep imaging dataset of unprecedented spatial resolution over the entire extra-Galactic sky. Here we will present the results of the study carried out by the Euclid Imaging Consortium during the Euclid Assessment Phase

Euclid: ESAs mission to map the geometry of the dark universe

Euclid is a space-borne sky survey mission designed to understand the origin of the Universe's accelerating expansion. The mission is optimised for two independent cosmological probes: weak gravitational lensing and galaxy clustering. The payload consists of a 1.2 m Korsch telescope with two instruments: a visual imager (VIS) and a near-infrared spectrometer-photometer (NISP). Both instruments cover a large common field of view of 0.54 deg2, enabling a sky survey of at least 15,000 deg2. A status overview of the mission is presented: the scientific objectives, payload, satellite, and science operations. Euclid's launch is foreseen in 2019

Euclid mission: building of a reference survey

International audienceEuclid is an ESA Cosmic-Vision wide-field-space mission which is designed to understand the acceleration of the Universe's expansion. The mission relies on two primary cosmological probes: Weak gravitational Lensing (WL) and Galaxy Clustering (in particular Baryon Acoustic Oscillations, BAO). The construction of a Reference Survey derived from the high level science requirements, the definition of a main sequence of observation and the associated calibrations was indeed a major achievement of the Definition Phase. Implementation of this sequence demonstrated the feasibility of covering the requested area in less than 6 years while taking into account the overheads of space segment observing and maneuvering sequence