Euclid is a European Space Agency mission dedicated to the mapping of the dark Universe launched the 1st of July 2023. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. This is achieved by measuring shapes and redshifts of galaxies and clusters of galaxies up to 10 billion years away. Euclid makes use of two cosmological probes, in a wide survey over the full extragalactic sky: the Weak Gravitational Lensing (WL) and the Baryonic Acoustic Oscillations (BAOs). The WL is a method to map the dark matter and measure dark energy by measuring the apparent distortion of galaxy images by mass inhomogeneities along the line-of-sight. This probe requires extreme image quality thus constraining the optical system imaging quality and its characterization both on-ground and in-flight. The BAOs are wiggle patterns, imprinted in the clustering of galaxies, which provide a standard ruler to measure dark energy and the expansion in the Universe. The first images were released on the 7th of November 2023 showcasing the capabilities of the space segment. To achieve the stunning first images and the scientific objectives of the mission, the space segment (i.e. the spacecraft) underwent a thorough and extensive test campaign on-ground. These tests demonstrated the excellent image quality and the overall stability of both the payload and the spacecraft in a representative operational environment. In complement, further tests were performed during the commissioning phase, just after launch, to validate the spacecraft pointing stability.
R. Laureijs, R. Vavrek, G. Racca, R. Kohley, P. Ferruit, V. Pettorino, T. Bönke, A. Calvi, L. Gaspar Venancio, L. Campos, E. Maiorano, O. Piersanti, S. Prezelus, U. Ragnit, P. Rosato, C. Rosso, H. Rozemeijer, A. Short, P. Strada, D. Stramaccioni, M. Szafraniec, B. Altieri, G. Buenadicha, X. Dupac, P. Gómez Cambronero, K. Henares Vilaboa, C. Hernandez de la Torre, J. Hoar, M. Lopez-Caniego Alcarria, P. Marcos Arenal, J. Martin Fleitas, M. Miluzio, A. Mora, S. Nieto, R. Perez Bonilla, P. Teodoro Idiago, F. Cordero, J. Mendes, F. Renk, A. Rudolph, M. Schmidt, J. Schwartz, Y. Mellier, H. Aussel, M. Berthé, P. Casenove, M. Cropper, J. Cuillandre, J. Dinis, A. Gregorio, K. Kuijken, T. Maciaszek, L. Miller, R. Scaramella, M. Schirmer, I. Tereno, A. Zacchei, S. Awan, G. Candini, P. Liebing, R. Nakajima, S. Dusini, P. Battaglia, E. Medinaceli, C. Sirignano, I. Baldry, C. Baugh, F. Bernardeau, F. Castander, A. Cimatti, W. Gillard, L. Guzzo, H. Hoekstra, K. Jahnke, T. Kitching, E. Martin, J. Mohr, W. Percival, J. Rhodes
During its 6-year nominal mission, Euclid shall survey one third of the sky, enabling us to examine the spatial distributions of dark and luminous matter during the past 10 Gyr of cosmic history. The Euclid satellite was successfully launched on a SpaceX Falcon 9 launcher from Cape Canaveral on 1 July 2023 and is fully operational in a halo orbit around the Second Sun-Earth Lagrange point. We present an overview of the expected and unexpected findings during the early phases of the mission, in the context of technological heritage and lessons learnt. The first months of the mission were dedicated to the commissioning of the spacecraft, telescope and instruments, followed by a phase to verify the scientific performance and to carry out the in-orbit calibrations. We report that the key enabling scientific elements, the 1.2-meter telescope and the two scientific instruments, a visual imager (VIS) and a near-infrared spectrometer and photometer (NISP), show an inorbit performance in line with the expectations from ground tests. The scientific analysis of the observations from the Early Release Observations (ERO) program done before the start of the nominal mission showed sensitivities better than the prelaunch requirements. The nominal mission started in December 2023, and we allocated a 6-month early survey operations phase to closely monitor the performance of the sky survey. We conclude with an outlook of the activities for the remaining mission in the light of the in-orbit performance.
Euclid, the M2 mission of the ESA’s Cosmic Vision 2015-2025 program, aims to explore the Dark Universe by conducting a survey of approximately 14 000 deg2 and creating a 3D map of the observable Universe of around 1.5 billion galaxies up to redshift z ∼ 2. This mission uses two main cosmological probes: weak gravitational lensing and galaxy clustering, leveraging the high-resolution imaging capabilities of the Visual Imaging (VIS) instrument and the photometric and spectroscopic measurements of the Near Infrared Spectrometer and Photometer (NISP) instrument. This paper details some of the activities performed during the commissioning phase of the NISP instrument, following the launch of Euclid on July 1, 2023. In particular, we focus on the calibration of the NISP detectors’ baseline and on the performance of a parameter provided by the onboard data processing (called NISP Quality Factor, QF) in detecting the variability of the flux of cosmic rays hitting the NISP detectors. The NISP focal plane hosts sixteen Teledyne HAWAII-2RG (H2RG) detectors. The calibration of these detectors includes the baseline optimization, which optimizes the dynamic range and stability of the signal acquisition. Additionally, this paper investigates the impact of Solar proton flux on the NISP QF, particularly during periods of high Solar activity. Applying a selection criterion on the QF (called NISP QF Proxy), the excess counts are used to monitor the amount of charged particles hitting the NISP detectors. A good correlation was found between the Solar proton flux component above 30 MeV and the NISP QF Proxy, revealing that NISP detectors are not subject to the lower energy components, which are absorbed by the shielding provided by the spacecraft.
The Euclid mission, the spacecraft being the essential space element, has been developed to undertake the challenges of investigate the dark energy and dark matter distribution in the Universe. As the launch date is approaching, the telescope and the integrated payload, encompassing the telescope and with the two science instruments attached behind it, have been successfully tested. The telescope alone was tested under ambient conditions, and the integrated payload was tested in vacuum at operational temperature. The extensive test campaign at telescope level confirmed that its optical performance were better than the required levels. The thermal-vacuum test campaign demonstrated the excellent stability of the optical performance of the entire payload module. In addition, other performances of the integrated payload were tested to gather information on the behavior of the payload which will be used for the preparation of the calibrations in-flight.
ESA’s mission Euclid while undertaking its final integration stage is fully qualified. Euclid will perform an extra galactic survey (0<z<2) using visible and near-infrared light. To detect the infrared radiation is equipped with the Near Infrared Spectro-Photometer (NISP) instrument with a sensitivity in the 0.9-2 μm range. We present an illustration of the NISP Data Processing Unit’s Application Software, highlighting the experimental process to obtain the final parametrization of the on-board processing of data produced by an array of 16 Teledyne’s HAWAII-2RG (HgCdTe) - each of 2048×2048 px2, 0.3 arcsec/px, 18 μm pixel pitch; using data from the latest test campaigns done with the flight configuration hardware - complete optical system (Korsh anastigmat telescope), detectors array (0.56 deg2 firld of view) and readout systems (16 Digital Control Units and Sidecar ASICs). Also, we show the outstanding Spectrometric (using a Blue and two Red Grisms) and Photometric (using YE 0.92-1.15μm, JE 1.15-1.37μm, and HE 1.37-2.0 μm filters) performances of the NISP detector derived from the end-to-end payload module test campaign at FOCAL 5 - CSL; among them the Photometric Point Spread Function (PSF) determination, and the Spectroscopic dispersion verification. Also the performances of the onboard processing are presented. Then, we describe the solution of a major issue found during this final test phase that put NISP in the critical path. We will describe how the problem was eventually understood and solved thanks to an intensive coordinated effort of an independent review team (tiger team lead by ESA) and a team of NISP experts from the Euclid Consortium. An extended PLM level campaign in ambient in Liege and a dedicated test campaign conducted in Marseille on the NISP EQM model, with both industrial and managerial support, finally confirmed the correctness of the diagnosis of the problem. Finally, the Euclid’s survey is presented (14000 deg2 wide survey, and ∼40 deg2 deep-survey) as well as the global statistics for a mission lifetime of 6 years (∼1.5 billion Galaxy’s shapes, and ∼50 million Galaxy’s spectra).
The NISP (Near Infrared Spectrometer and Photometer) is one of the two Euclid instruments (see ref [1]). It operates in the near-IR spectral region (950-2020nm) as a photometer and spectrometer. The instrument is composed of: - a cold (135K) optomechanical subsystem consisting of a Silicon carbide structure, an optical assembly, a filter wheel mechanism, a grism wheel mechanism, a calibration unit and a thermal control system - a detection system based on a mosaic of 16 H2RG with their front-end readout electronic. - a warm electronic system (290K) composed of a data processing / detector control unit and of an instrument control unit that interfaces with the spacecraft via a 1553 bus for command and control and via Spacewire links for science data This paper presents: - the final architecture of the flight model instrument and subsystems - the performances and the ground calibration measurement done at NISP level and at Euclid Payload Module level at operational cold temperature.
The Euclid mission, of which the spacecraft is the essential space segment, is being developed to undertake the challenges of mapping the dark energy and dark matter distribution in the Universe. As the launch date is approaching (2nd half of 2022), the development of the spacecraft has successfully passed critical milestones with the manufacturing and integration of the telescope, instruments and service module. Each sub-element of the spacecraft has been qualified and their performance assessed. The assembly of the complete payload and spacecraft is currently on-going. The integrated optical performance end to end of the payload module is currently being assessed based on the as-built knowledge of the parts of the telescope and instruments.
Euclid, an ESA mission designed to characterise dark energy and dark matter, passed its Mission Critical Design Review in November 2018. It was demonstrated that the project is ready to start integration and test of the main systems, and that it has the ability to fulfil its top-level mission requirements. In addition, based on the performances at M-CDR, the scientific community has verified that the science requirements can be achieved for the Weak Lensing and Galaxy Clustering dark energy probes, namely a dark energy Figure of Merit of 400 and a 2% accuracy in the growth factor exponent gamma. We present the status of the main elements of the Euclid mission in the light of the demanding high optical performance which is the essential design driver is the to meet the scientific requirements. We include the space segment comprising of a service module and payload module hosting the telescope and its two scientific instruments, and the ground segment, which encompasses the operational and science ground segment. The elements for the scientific success of the mission for a timely release of the data are shortly presented: the processing and calibration of the data, and the design of the sky survey. Euclid is presently on schedule for a launch in September 2022.
In the framework of the ESA’s Science programme, the Euclid mission has the objective to map the geometry of the Dark Universe. For the Near Infrared Spectrometer and Photometer instrument (NISP), the state-of-the-art HAWAII-2RG detectors will be used, in association with the SIDECAR ASIC readout electronics. A dedicated test bench has been designed, developed and validated at ESTEC to perform tests on these detectors. This test bench is equipped with a spot projector system as well as a set of LEDs allowing to project the Euclid like beam and perform persistence measurements. The detector under test shows crosshatch patterns that may correspond to sub-pixel variations in Quantum Efficiency or charge redistribution. The goal of the tests was to evaluate the impact of crosshatches patterns on the Euclid photometric performance and centroid calculation after flat fielding correction. The second part of the publication discusses different persistence mitigation tests using the LEDs test set up.
Euclid is an ESA mission to map the geometry of the dark Universe with a planned launch date in 2021. Euclid is optimised for two primary cosmological probes, weak gravitational lensing and baryonic acoustic oscillations. They are implemented through two science instruments on-board Euclid, a visible imager (VIS) and a near-infrared photometer/spectrometer (NISP), which are being developed and built by the Euclid Consortium instrument development teams. The NISP instrument contains a large focal plane assembly of 16 Teledyne HgCdTe H2RG detectors with 2.3 μm cut-off wavelength and SIDECAR readout electronics. The performance of the detector systems is critical for the science return of the mission and extended on-ground tests are being performed for characterisation and calibration purposes. Special attention is given also to effects even on the scale of individual pixels, which are difficult to model and calibrate, and to identify any possible impact on science performance. This paper discusses the known effect of random telegraph signal (RTS) in a follow-on study of test results from the Euclid NISP detector system demonstrator model [1], addressing open issues and focusing on an in-depth analysis of the RTS behaviour over the pixel population on the studied Euclid H2RGs.
Euclid is an ESA mission to map the geometry of the dark Universe with a planned launch date in 2020. Euclid is optimised for two primary cosmological probes, weak gravitational lensing and galaxy clustering. They are implemented through two science instruments on-board Euclid, a visible imager (VIS) and a near-infrared spectro-photometer (NISP), which are being developed and built by the Euclid Consortium instrument development teams. The NISP instrument contains a large focal plane assembly of 16 Teledyne HgCdTe HAWAII-2RG detectors with 2.3μm cut-off wavelength and SIDECAR readout electronics. While most Euclid NISP detector system on-ground tests involve flat-field illumination, some performance tests require point-like sources to be projected onto the detector. For this purpose a dedicated test bench has been developed by ESA at ESTEC including a spot projector capable of generating a Euclid-like PSF. This paper describes the test setup and results from two characterisation tests involving the spot projector. One performance parameter to be addressed by Euclid is image (charge) persistence resulting from previous exposures in the science acquisition sequence. To correlate results from standard on-ground persistence tests from flat-field illumination to realistic scenes, the persistence effect from spot illumination has been evaluated and compared to the flat-field. Another important aspect is the photometric impact of intra-pixel response variations. Preliminary results of this measurement on a single pixel are presented.
Euclid is an ESA mission to map the geometry of the dark Universe with a planned launch date in 2020. Euclid is optimised for two primary cosmological probes, weak gravitational lensing and galaxy clustering. They are implemented through two science instruments on-board Euclid, a visible imager (VIS) and a near-infrared spectro-photometer (NISP), which are being developed and built by the Euclid Consortium instrument development teams. The NISP instrument contains a large focal plane assembly of 16 Teledyne HgCdTe H2RG detectors with 2.3μm cut-off wavelength and SIDECAR readout electronics. The performance of the detector systems is critical to the science return of the mission and extended on-ground tests are being performed for characterisation and calibration purposes. Special attention is given also to effects even on the scale of individual pixels, which are difficult to model and calibrate, and to identify any possible impact on science performance. This paper discusses a variety of undesired pixel behaviour including the known effect of random telegraph signal (RTS) noise based on initial on-ground test results from demonstrator model detector systems. Some stability aspects of the RTS pixel populations are addressed as well.
In support of the European space agency (ESA) Euclid mission, NASA is responsible for the evaluation of the H2RG mercury cadmium telluride (MCT) detectors and electronics assemblies fabricated by Teledyne imaging systems. The detector evaluation is performed in the detector characterization laboratory (DCL) at the NASA Goddard space flight center (GSFC) in close collaboration with engineers and scientists from the jet propulsion laboratory (JPL) and the Euclid project. The Euclid near infrared spectrometer and imaging photometer (NISP) will perform large area optical and spectroscopic sky surveys in the 0.9-2.02 μm infrared (IR) region. The NISP instrument will contain sixteen detector arrays each coupled to a Teledyne SIDECAR application specific integrated circuit (ASIC). The focal plane will operate at 100K and the SIDECAR ASIC will be in close proximity operating at a slightly higher temperature of 137K. This paper will describe the test configuration, performance tests and results of the latest engineering run, also known as pilot run 3 (PR3), consisting of four H2RG detectors operating simultaneously. Performance data will be presented on; noise, spectral quantum efficiency, dark current, persistence, pixel yield, pixel to pixel uniformity, linearity, inter pixel crosstalk, full well and dynamic range, power dissipation, thermal response and unit cell input sensitivity.
Cleanliness specifications for infrared detector arrays are usually so stringent that effects are neglibile. However, the specifications determine only the level of particulates and areal density of molecular layer on the surface, but the chemical composition of these contaminants are not specified. Here, we use a model to assess the impact on system quantum efficiency from possible contaminants that could accidentally transfer or cryopump to the detector during instrument or spacecraft testing and on orbit operation. Contaminant layers thin enough to meet typical specifications, < 0.5μgram/cm2, have a negligible effect on the net quantum efficiency of the detector, provided that the contaminant does not react with the detector surface, Performance impacts from these contaminant plating onto the surface become important for thicknesses 5 - 50μgram/cm2. Importantly, detectable change in the ”ripple” of the anti reflection coating occurs at these coverages and can enhance the system quantum efficiency. This is a factor 10 less coverage for which loss from molecular absorption lines is important. Thus, should contamination be suspected during instrument test or flight, detailed modelling of the layer on the detector and response to very well known calibrations sources would be useful to determine the impact on detector performance.
The Euclid mission objective is to understand why the expansion of the Universe is accelerating through by mapping the geometry of the dark Universe
by investigating the distance-redshift relationship and tracing the evolution of cosmic structures. The Euclid project is part of ESA's Cosmic Vision
program with its launch planned for 2020 (ref [1]).
The NISP (Near Infrared Spectrometer and Photometer) is one of the two Euclid instruments and is operating in the near-IR spectral region (900-
2000nm) as a photometer and spectrometer. The instrument is composed of:
- a cold (135K) optomechanical subsystem consisting of a Silicon carbide structure, an optical assembly (corrector and camera lens), a filter wheel
mechanism, a grism wheel mechanism, a calibration unit and a thermal control system
- a detection subsystem based on a mosaic of 16 HAWAII2RG cooled to 95K with their front-end readout electronic cooled to 140K, integrated on a
mechanical focal plane structure made with molybdenum and aluminum. 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 that interfaces with the
spacecraft via a 1553 bus for command and control and via Spacewire links for science data
This presentation describes the architecture of the instrument at the end of the phase C (Detailed Design Review), the expected performance, the
technological key challenges and preliminary test results obtained for different NISP subsystem breadboards and for the NISP Structural and Thermal
model (STM).
KEYWORDS: Data processing, Galactic astronomy, Space operations, Telescopes, Point spread functions, K band, Sensors, Image quality, Data archive systems, Calibration
Euclid is a space-based optical/near-infrared survey mission of the European Space Agency (ESA) to investigate the
nature of dark energy, dark matter and gravity by observing the geometry of the Universe and on the formation of
structures over cosmological timescales. Euclid will use two probes of the signature of dark matter and energy: Weak
gravitational Lensing, which requires the measurement of the shape and photometric redshifts of distant galaxies, and
Galaxy Clustering, based on the measurement of the 3-dimensional distribution of galaxies through their spectroscopic
redshifts. The mission is scheduled for launch in 2020 and is designed for 6 years of nominal survey operations. The
Euclid Spacecraft is composed of a Service Module and a Payload Module. The Service Module comprises all the
conventional spacecraft subsystems, the instruments warm electronics units, the sun shield and the solar arrays. In
particular the Service Module provides the extremely challenging pointing accuracy required by the scientific objectives.
The Payload Module consists of a 1.2 m three-mirror Korsch type telescope and of two instruments, the visible imager
and the near-infrared spectro-photometer, both covering a large common field-of-view enabling to survey more than
35% of the entire sky. All sensor data are downlinked using K-band transmission and processed by a dedicated ground
segment for science data processing. The Euclid data and catalogues will be made available to the public at the ESA
Science Data Centre.
Euclid is an European Space Agency (ESA) mission to map the geometry of the dark Universe. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. It will achieve this by measuring shapes and redshifts of galaxies and clusters of galaxies out to redshifts ~2, equivalent to 10 billion years back in time. Euclid will make use of two primary cosmological probes, in a wide survey over the full extragalactic sky : the Weak Gravitational Lensing (WL) and Baryon Acoustic Oscillations (BAO). The main goal of the Euclid payload module (PLM) is to provide high quality imaging of galaxies and accurate measurement (less than 0.1%) of galaxies redshift over a large field of view (FoV). The present paper focuses on the telescope of the PLM excluding the instruments. We present a brief introduction to the Euclid PLM system and will report how the constraints of each instrument have driven the definition of the telescope-to-instrument optical interfaces. Furthermore we introduce the description of the telescope optical characteristics and report its nominal performances. Finally, the technical challenges to be faced by ESA’s industrial partners are underlined.
In June 2012, Euclid, ESA's Cosmology mission was approved for implementation. Afterwards the industrial contracts were signed for the payload module and the spacecraft prime, and the mission requirements consolidated. We present the status of the mission in the light of the design solutions adopted by the contractors. The performances of the spacecraft in its operation, the telescope assembly, the scientific instruments as well as the data-processing have been carefully budgeted to meet the demanding scientific requirements. We give an overview of the system and where necessary the key items for the interfaces between the subsystems.
The Euclid mission objective is to understand why the expansion of the Universe is accelerating by mapping the geometry of the dark Universe by
investigating the distance-redshift relationship and tracing the evolution of cosmic structures. The Euclid project is part of ESA's Cosmic Vision
program with its launch planned for 2020.
The NISP (Near Infrared Spectro-Photometer) is one of the two Euclid instruments and is operating in the near-IR spectral region (0.9-2μm) as a
photometer and spectrometer. The instrument is composed of:
- a cold (135K) optomechanical subsystem consisting of a SiC structure, an optical assembly (corrector and camera lens), a filter wheel mechanism, a
grism wheel mechanism, a calibration unit and a thermal control system
- a detection subsystem based on a mosaic of 16 Teledyne HAWAII2RG cooled to 95K with their front-end readout electronic cooled to 140K,
integrated on a mechanical focal plane structure made with Molybdenum and Aluminum. 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 that interfaces with the
spacecraft via a 1553 bus for command and control and via Spacewire links for science data
This presentation describes the architecture of the instrument at the end of the phase B (Preliminary Design Review), the expected performance, the
technological key challenges and preliminary test results obtained on a detection system demonstration model.
The Near-Infrared Spectrograph (NIRSpec) is one of the four science instruments of the James Webb Space Telescope. Its focal plane consists of two HAWAII-2RG sensors operating in the wavelength range of 0.6 to 5.0 µm and, as part of characterizing NIRSpec, the noise properties of these detectors under dark and illuminated conditions were studied. Under dark conditions, and as already known, 1/f noise in the detector system causes somewhat higher noise levels than can be accounted for by a simple model that includes white read noise and shot noise on integrated charge. More surprisingly, for high levels of accumulated charge, significantly lower total noise than expected was observed. This effect is shown to be due to pixel-to-pixel correlations introduced by signal-dependent interpixel crosstalk, with an interpixel coupling factor, α , that ranges from ∼0.01 for zero signal to ∼0.03 close to saturation.
KEYWORDS: Sensors, Interference (communication), Signal detection, James Webb Space Telescope, Cadmium sulfide, Infrared sensors, Quantum efficiency, Capacitance, Spectrographs, Signal processing
NIRSpec (Near Infrared Spectrograph) is one of the four science instruments of the James Webb Space Telescope
(JWST) and its focal plane consists of two HAWAII-2RG sensors operating in the wavelength range 0.6−5.0μm.
As part of characterizing NIRSpec, we studied the noise properties of these detectors under dark and illuminated
conditions. Under dark conditions, and as already known, 1/f noise in the detector system produces somewhat
more noise than can be accounted for by a simple model that includes white read noise and shot noise on
integrated charge. More surprisingly, at high flux, we observe significantly lower total noise levels than expected.
We show this effect to be due to pixel-to-pixel correlations introduced by signal dependent inter-pixel crosstalk,
with an inter-pixel coupling factor, α, that ranges from ~ 0.01 for zero signal to ~ 0.03 close to saturation.
Pierre Ferruit, Giorgio Bagnasco, Reiner Barho, Stephan Birkmann, Torsten Böker, Guido De Marchi, Bernhard Dorner, Ralf Ehrenwinkler, Massimo Falcolini, Giovanna Giardino, Xavier Gnata, Karl Honnen, Peter Jakobsen, Peter Jensen, Manfred Kolm, Hans-Ulrich Maier, Ralf Maurer, Markus Melf, Peter Mosner, Peter Rumler, Jean-Christophe Salvignol, Marco Sirianni, Paolo Strada, Maurice te Plate, Thomas Wettemann
The Near-Infrared Spectrograph NIRSpec is one of the four instruments of the James Webb Space Telescope (JWST).
NIRSpec will cover the 0.6-5.0 micron range and will be capable of obtaining spectra of more than 100 objects
simultaneously in its multi-object spectroscopy (MOS) mode. It also features a set of slits and an aperture for high
contrast spectroscopy of individual sources, as well as an integral-field unit (IFU) for 3D spectroscopy. We will first
show how these capabilities are linked to the four main JWST scientific themes. We will then give an overview of the
NIRpec modes and spectral configurations with an emphasis on the layout of the field of view and of the spectra. Last,
we will provide an update on the status of the instrument.
The Near Infrared Spectrograph (NIRSpec) is one of the four science instruments aboard the James Webb Space
Telescope (JWST) scheduled for launch in 2014. NIRSpec is sensitive in the wavelength range from ~ 0.6 to
5.0 μm and will be capable of obtaining spectra of more than a 100 objects simultaneously, as well as fixed slit
high contrast spectroscopy of individual sources. It also features an integral field unit for 3D spectroscopy. The
key scientific objectives of the instrument include studies of star formation and chemical abundances of young
distant galaxies and tracing the creation of the chemical elements back in time. In this paper, we present the
status of the NIRSpec instrument as it is currently being prepared for its extensive ground calibration campaign
later in 2010.
KEYWORDS: Sensors, James Webb Space Telescope, Electronics, Near infrared, Calibration, Infrared sensors, Space telescopes, Infrared telescopes, Infrared radiation, Astronomy
The James Webb Space Telescope, an infrared-optimized space telescope being developed by NASA for launch in 2014,
will utilize cutting-edge detector technology in its investigation of fundamental questions in astrophysics. JWST's near
infrared spectrograph, NIRSpec utilizes two 2048 × 2048 HdCdTe arrays with Sidecar ASIC readout electronics
developed by Teledyne to provide spectral coverage from 0.6 microns to 5 microns. We present recent test and
calibration results for the "pathfinder NIRSpec detector subsystem" as well as data processing routines for noise
reduction and cosmic ray rejection.
The James Webb Space Telescope (JWST) Near Infrared Spectrograph (NIRSpec) incorporates two 5 μm cutoff
(λco =5 μm) 2048×2048 pixel Teledyne HgCdTe HAWAII-2RG sensor chip assemblies. These detector arrays,
and the two Teledyne SIDECAR application specific integrated circuits that control them, are operated in space
at Τ ~ 37 K. This article focuses on the measured performance of the first flight-candidate, and near-flight
candidate, detector arrays. These are the first flight-packaged detector arrays that meet NIRSpec's challenging
6 e- rms total noise requirement. The current version of this paper has had a correction made to it at the request of the author. Please see the linked Errata for further details.
The James Webb Space Telescope (JWST) mission is a collaborative project between the National Aeronautics and
Space Administration (NASA), the European Space Agency (ESA) and the Canadian Space Agency (CSA).
JWST is considered the successor to the Hubble Space Telescope (HST) and although its design and science objectives
are quite different, JWST is expected to yield equivalently astonishing breakthroughs in infrared space science.
Due to be launched in 2013 from the French Guiana, the JWST observatory will be placed in an orbit around the anti-
Sun Earth-Sun Lagrangian point, L2, by an Ariane 5 launcher, provided by ESA.
The payload on board the JWST observatory consists of four main scientific instruments: a near-infrared camera
(NIRCam), a combined mid-infrared camera/spectrograph (MIRI), a near-infrared tunable filter (TFI) and a nearinfrared
spectrograph (NIRSpec). The instrument suite is completed by a Fine Guidance Sensor (FGS).
Besides the provision of the Ariane 5 launcher, ESA, with EADS Astrium GmbH (D) as Prime Contractor, is fully
responsible for the funding and the furnishing of NIRSpec and, at the same time, for approximately half of MIRI costs
through special contributions from the ESA member states.
NIRSpec is a multi-object, spectrograph capable of measuring the spectra of about 100 objects simultaneously at low
(R=100), medium (R=1000), and high (R=2700) resolutions over the wavelength range between 0.6 micron and 5.0
micron. In this article we provide a general overview of its main design features and performances.
KEYWORDS: James Webb Space Telescope, Sensors, Spectrographs, Staring arrays, Near infrared, Space telescopes, Silicon, Infrared sensors, Infrared telescopes, Cameras
The Near Infrared Spectrograph (NIRSpec) will be the James Webb Space Telescope's (JWST's) primary near-infrared spectrograph. NIRSpec is a multi-object spectrograph with fixed-slit and integral field modes. EADS/Astrium is building NIRSpec for the European Space Agency (ESA), with NASA is providing the detector subsystem and programmable multi-aperture mask. In this paper, we summarize recent progress on the detector subsystem including tests demonstrating that JWST's Rockwell HAWAII-2RG sensor chip assemblies have achieved Technology Readiness Level 6 (TRL-6). Achieving TRL-6 is an important milestone because TRL-6 is required for flight.
The Near-Infrared Spectrograph (NIRSpec) is the James Webb Space Telescope’s primary near-infrared spectrograph. NASA is providing the NIRSpec detector subsystem, which consists of the focal plane array, focal plane electronics, cable harnesses, and software. The focal plane array comprises two closely-butted λco ~ 5 μm Rockwell HAWAII-2RG sensor chip assemblies. After briefly describing the NIRSpec instrument, we summarize some of the driving requirements for the detector subsystem, discuss the baseline architecture (and alternatives), and presents some recent detector test results including a description of a newly identified noise component that we have found in some archival JWST test data. We dub this new noise component, which appears to be similar to classical two-state popcorn noise in many aspects, “popcorn mesa noise.” We close with the current status of the detector subsystem development effort.
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