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.
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 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.
This paper describes the engineering and mechanical considerations in the design and construction of a carbon fiber containment vessel for a photometric camera. The camera is intended for installation on the 4 m William Herschel Telescope, located in Palma, Spain. The scientific objective of the camera system is to measure red-shifts of a large sample of galaxies using the photometric technique. The paper is broken down into sections, divided by the principal engineering challenges of the project; the carbon fiber vacuum vessel, the cooling systems and the precision movement systems.
PAUCam is a large field of view camera designed to exploit the field delivered by the prime focus corrector of the William Herschel Telescope, at the Observatorio del Roque de los Muchachos. One of the new features of this camera is its filter system, placed within a few millimeters of the focal plane using eleven trays containing 40 narrow band and 6 broad band filters, working in vacuum at an operational temperature of 250K and in a focalized beam. In this contribution, we describe the performance of these filters both in the characterization tests at the laboratory.
The PAU (Physics of the Accelerating Universe) project goal is the study of dark energy with a new photometric technique aiming at obtaining photo-z resolution for Luminous Red Galaxies (LRGs) roughly one order of magnitude better than current photometric surveys. To accomplish this, a new large field of view camera (PAUCam) has been built and commissioned at the William Herschel Telescope (WHT). With the current WHT corrector, the camera covers ~1 degree diameter Field of View (FoV). The focal plane consists of 18 2kx4k Hamamatsu fully depleted CCDs, with high quantum efficiency up to 1 μm. To maximize the detector coverage within the FoV, filters are placed in front of the CCD's inside the camera cryostat (made of carbon fiber material) using a challenging movable tray system. The camera uses a set of 40 narrow band filters ranging from ~4400 to ~8600 angstroms complemented with six standard broad-band filters, ugrizY. Here, we describe the camera and its first commissioning results. The PAU project aims to cover roughly 100 square degrees and to obtain accurate photometric redshifts for galaxies down to iAB ~ 22:5 detecting also galaxies down to iAB ~ 24 with less precision in redshift. With this data set we will obtain competitive constraints in cosmological parameters using both weak lensing and galaxy clustering as main observational probes.
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).
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 Physics of the Accelerating Universe (PAU) is a project whose main goal is the study of dark energy. For this purpose, a new large field of view camera (the PAU Camera, PAUCam) is being built. PAUCam is designed to carry out a wide area imaging survey with narrow and broad band filters spanning the optical wavelength range. The PAU Camera is now at an advance stage of construction. PAUCam will be mounted at the prime focus of the William Herschel Telescope. With the current WHT corrector, it will cover a 1 degree diameter field of view. PAUCam mounts eighteen 2k×4k Hamamatsu fully depleted CCDs, with high quantum efficiency up to 1 μm. Filter trays are placed in front of the CCDs with a technologically challenging system of moving filter trays inside the cryostat. The PAU Camera will use a new set of 42 narrow band filters ranging from ~4400 to ~8600 angstroms complemented with six standard broad-band filters, ugrizY. With PAUCam at the WHT we will carry out a cosmological imaging survey in both narrow and broad band filters that will perform as a low resolution spectroscopic survey. With the current survey strategy, we will obtain accurate photometric redshifts for galaxies down to iAB~22.5 detecting also galaxies down to iAB~24 with less precision in redshift. With this data set we will obtain competitive constraints in cosmological parameters using both weak lensing and galaxy clustering as main observational probes.
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