Large-format infrared detectors are at the heart of major ground and space-based astronomical instruments, and the HgCdTe HxRG is the most widely used. The Near Infrared Spectrometer and Photometer (NISP) of the ESA’s Euclid mission launched in July 2023 hosts 16 H2RG detectors in the focal plane. Their performance relies heavily on the effect of image persistence, which results in residual images that can remain in the detector for a long time contaminating any subsequent observations. Deriving a precise model of image persistence is challenging due to the sensitivity of this effect to observation history going back hours or even days. Nevertheless, persistence removal is a critical part of image processing because it limits the accuracy of the derived cosmological parameters. We will present the empirical model of image persistence derived from ground characterization data, adapted to the Euclid observation sequence and compared with the data obtained during the in-orbit calibrations of the satellite.
Launched successfully on July 1st, 2023, Euclid, the M2 mission of the ESA cosmic vision program, aims mainly at understanding the origin of the accelerated expansion of the Universe. Along with a visible imager VIS, it is equipped with the NISP instrument, a Near Infrared Spectrometer and Photometer, bespoke tailored to perform a 3D mapping of the observable Universe. It operates in the near-infrared spectral range, from 900 nm to 2000 nm with 2 observing modes: as a spectrometer, the NISP instrument will permit measuring millions of galaxy spectroscopic redshifts over the 6.5 years lifetime of the Euclid mission; as a photometer, it will obtain photometric redshifts of billions of galaxies. This paper provides a description of the NISP instrument, its scientific objectives, and offers an assessment of its current performance in flight.
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.
Euclid is a European Space Agency (ESA) wide-field space mission dedicated to the high-precision study of dark energy and dark matter. In July 2023 a Space X Falcon 9 launch vehicle put the spacecraft in its target orbit, located 1.5 million kilometers away from Earth, for a nominal lifetime of 6.5 years. The survey will be realized through a wide field telescope and two instruments: a visible imager (VIS) and a Near Infrared Spectrometer and Photometer (NISP). NISP is a state-of-the-art instrument composed of many subsystems, including an optomechanical assembly, cryogenic mechanisms, and active thermal control. The Instrument Control Unit (ICU) is interfaced with the SpaceCraft and manages the commanding and housekeeping production while the high-performance Data Processing Unit manages more than 200 Gbit of compressed data acquired daily during the nominal survey. To achieve the demanding performance necessary to meet the mission’s scientific goals, NISP requires periodic in-flight calibrations, instrument parameters monitoring, and careful control of systematic effects. The high stability required implies that operations are coordinated and synchronized with high precision between the two instruments and the platform. Careful planning of commanding sequences, lookahead, and forecasting instrument monitoring is needed, with greater complexity than previous survey missions. Furthermore, NISP is operated in different environments and configurations during development, verification, commissioning, and nominal operations. This paper presents an overview of the NISP instrument operations at the beginning of routine observations. The necessary tools, workflows, and organizational structures are described. Finally, we show examples of how instrument monitoring was implemented in flight during the crucial commissioning phase, the effect of intense Solar activity on the transmission of onboard data, and how IOT successfully addressed this issue.
Euclid is a major ESA mission scheduled for launch in 2023-2024 to map the geometry of the dark Universe using two primary probes, weak gravitational lensing and galaxy clustering. Euclid’s instruments, a visible imager (VIS) and an infrared spectrometer and photometer (NISP) have both been designed and built by Euclid Consortium teams. The NISP instrument will hold a large focal plane array of 16 near-infrared H2RG detectors, which are key elements to the performance of the NISP, and therefore to the science return of the mission.
Euclid NISP H2RG flight detectors have been individually and thoroughly characterized at Centre de Physique des Particules de Marseille (CPPM) during a whole year with a view to producing a reference database of performance pixel maps. Analyses have been ongoing and have shown the relevance of taking into account spatial variations in deriving performance parameters. This paper will concentrate on interpixel capacitance (IPC) and conversion gain. First, per pixel IPC coefficient maps will be derived thanks to single pixel reset (SPR) measurements and a new IPC correction method will be defined and validated. Then, the paper will look into correlation effects of IPC and their impact on the derivation of per super-pixel IPC-free conversion gain maps. Eventually, several conversion gain values will be defined over clearly distinguishable regions.
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.
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 a major ESA mission for the study of dark energy planned to launch in 2021. Euclid will probe the expansion history of the Universe using weak lensing and baryonic acoustic oscillations probes. A survey of 15,000 deg2 of the sky with the instrument NISP (Near-Infrared Spectro-Photometer), in the 900 – 2100 nm band, will give both the photometric and spectrometric redshifts of tens of millions of galaxies. The 16 H2RG detectors of the NISP focal plane array are still being characterized at CPPM (Marseille). Already 16 out of 20 flight detectors have been tested and a straightforward analysis done. Performance of the dedicated test benches – in particular control of flux and temperature – as well as an overview of the test flow will be presented. This paper will present methods and some preliminary results on two detectors focusing on the determination of a per pixel conversion gain.
Euclid is an ESA mission to map the geometry of the Dark Universe with a planned launch date in 2021.1 Two
primary cosmological probes, weak gravitational lensing and baryonic acoustic oscillations, are implemented
through a VISible imager (VIS) and a Near-Infrared Spectrometer and Photometer (NISP).2 The ground characterization of the NISP Flight Sensor Chip Systems (SCS) followed by the pixel response calibration aims to
produce all informations to correct and control the accuracy of the signal. This work reports on the ground
characterization of the NISP detector chain. The detector and electrical effects are likely to generate statistical
fluctuations and systematic errors on the final flux measurement. The analysis strategies to maintain the pixel
relative response accuracy within 1% is proposed in this work. The Euclid NISP test ow is presented and
the main concerns of the detector chain calibration, such as non-linearity, charge trapping and de-trapping are
discussed on the basis of the analysis of the flight detectors characterization data.
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.
Euclid mission is designed to understand the dark sector of the universe. Precise redshift measurements are provided by H2RG detectors. We propose an unbiased method of fitting the flux with Poisson distributed and correlated data, which has an analytic solution and provides a reliable quality factor - fundamental features to ensure the goals of the mission. We compare our method to other techniques of signal estimation and illustrate the anomaly detection on the flight-like detectors. Although our discussion is focused on Euclid NISP instrument, much of what is discussed will be of interest to any mission using similar near-infrared sensors.
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).
Euclid, a major ESA mission for the study of dark energy, will offer a large survey of tens of millions of galaxies thanks to its Near-Infrared Spectro-Photometer. For it to be successful, the 16 Teledyne's 2.3 μm cutoff 2048x2048 pixels IR HgCdTe detectors of the focal plane must show very high performances over more than 95% of pixels, in terms of median dark current, total noise, budget error on non-linearity after correction, residual dark due to latency effects and quantum efficiency. This will be verified through a thorough characterization of their performances, leading to the production of the pixel map calibration database for the Euclid mission. Characterization is challenging in many ways: each detector will have to be fully and accurately characterized in less than three weeks, with rather tight requirements: dark current at the 10-3 e-/s level with 10% accuracy, relative Pixel Response map better than 1%, obtained with an illumination flatness better than 1%, measurements alternating dark and high level illumination taking care of latency impacts. Due to statistics needs, very long runs (24h without interrupts) of scripted measurements would be executed. Systematics of the test bench should be at the end the limiting factor of the parameter measurement accuracy. Test plan, facilities with functionalities developed for those specific purposes and associated performances will be described.
The detector system (DS) of Euclid NISP’s instrument (Near-Infrared Spectro-Photometer) is a matrix of 16 H2RG infrared detectors acquired simultaneously. After their characterization done at CPPM (Centre de Physique des Particules de Marseille), these detectors are integrated into a mechanical structure designed at LAM (Laboratoire d'Astronomie de Marseille) and called NI-FPA (Focal Plane Array) Before delivering the full instrument to ESA several test models have to demonstrate the performances of the detector system. The first test model, the Demonstrator Model (DM), has been integrated and tested in dedicated facilities at LAM. The aim was to validate both the integration process and the simultaneous acquisition of the detectors. Dark, noise, self-compatibility and EMC performances are presented in this paper.
The success of the Euclid's NISP (Near-Infrared Spectro-Photometer) instrument for the Euclid mission requires very high performance detectors for which tight specifications have been defined. These must be verified over more than 95% of the focal plane which is equipped with 16 H2RG infrared pixel detectors. Teledyne will provide these detectors and their electronics under ESA and NASA contracts. The detectors will be selected, qualified then delivered to the NISP instrument under Euclid specifications. To prepare the future calibration plan, these detectors must also be fully characterized at the pixel level before their integration. This characterization is crucial to the future processing and in-flight calibration. For a good control of the performance, the detector specifications for Euclid require in one hand to know some characteristics such as noise and dark current at a level as low as 10-3 e- /s , but also in other hand, require to have model of some specific properties of these detectors such as their non-linearity response, or their latency signals, which will imply specific measurements, characterization and studies. For this purpose, we have constructed dedicated facilities, and prepared a full test plan with adapted analysis methods and software tools that will be used to calibrate flight detectors. Here we describe the status of this plan, the facilities and their validation. We then present some preliminary results on dark current, total noise, CDS noise and some first estimations of persistence, using high performance engineering grade Euclid detectors provided by ESA. A pilot run is foreseen at the end of the year to validate the full test plan. Next step will be the characterization of flight detectors expected to start mid 2016.
We derive the full covariance matrix equations for proper treatment of correlations in signal fitting procedures, extending the results from previous publications. The straight line fits performed with these matrices demonstrate that a significantly higher signal to noise is obtained when the fluence exceeds 1 e−/s/pixel, in particular in long (several hundreds of seconds) spectroscopic exposures. The improvement arising from the covariance matrix is particularly significant for the initial intercept of the fit at t=0, a quantity which provides a useful redundancy to cross check the signal quality. We demonstrate that the mode that maximizes the signal-to-noise ratio in all ranges of fluxes studied is the one that uses all the frames sampled during the exposure. While there is no restriction on the organization of frames within groups for fluences lower than 1 e−/s/pixel, the co-adding of frames should be avoided whenever the fluence exceeds this value.
We characterize at pixel level a NIR H2RG detector read with SIDECAR ASIC, similar to the detectors used in Euclid's Near IR Spectrometer Photometer (NISP). We derive the full covariance matrix formulae, extending the results from previous publications, and compare them to data and simulations for NISP baseline operating modes. The nonlinear response of the detector is measured and high precision maps are derived for in-flight or on-ground correction. High precision maps of the conversion gain are also determined using the Photon Transfer Curve technique.
We present the readout noise reduction methods and the 1/f noise response of an 2K × 2K HgCdTe detector similar to the detectors that will be used in the Near Infrared Spectrometer Photometer - one of the instruments of the future ESA mission named Euclid. Various algorithms of common modes subtraction are defined and compared. We show that the readout noise can be lowered by 60% using properly the references provided within the array. A predictive model of the 1/f noise with a given frequency power spectrum is defined and compared to data taken in a wide range of sampling frequencies. In view of this model the definition of ad-hoc readout noises for different sampling can be avoided.
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