CAGIRE: a wide-field NIR imager for the COLIBRI 1.3 meter robotic telescope

The use of high energy transients such as Gamma Ray Bursts (GRBs) as probes of the distant universe relies on the close collaboration between space and ground facilities. In this context, the Sino-French mission SVOM has been designed to combine a space and a ground segment and to make the most of their synergy. On the ground, the 1.3 meter robotic telescope COLIBRI, jointly developed by France and Mexico, will quickly point the sources detected by the space hard X-ray imager ECLAIRs, in order to detect and localise their visible/NIR counterpart and alert large telescopes in minutes. COLIBRI is equipped with two visible cameras, called DDRAGO-blue and DDRAGO-red, and an infrared camera, called CAGIRE, designed for the study of high redshift GRBs candidates. Being a low-noise NIR camera mounted at the focus of an alt-azimutal robotic telescope imposes specific requirements on CAGIRE. We describe here the main characteristics of the camera: its optical, mechanical and electronics architecture, the ALFA detector, and the operation of the camera on the telescope. The instrument description is completed by three sections presenting the calibration strategy, an image simulator incorporating known detector effects, and the automatic reduction software for the ramps acquired by the detector. This paper aims at providing an overview of the instrument before its installation on the telescope.Comment: Accepted by Experimental Astronom

Random telegraph signal (RTS) in the Euclid IR H2RGs

International audienceEuclid 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 flight H2RG IR detectors: per pixel conversion gain from on-ground characterization for the Euclid NISP instrument

International audienceEuclid 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

Detector chain calibration strategy for the Euclid Flight IR H2RGs

International audienceEuclid 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

Flux reconstruction for the NIR camera CAGIRE at the focus of the Colibrí telescope

International audienceCAGIRE is the near infrared camera of the Colibrí robotic telescope, designed for the follow-up of SVOM alerts. It is based on the ALFA 2k x 2k detector, from the LYNRED French Company, operating in "Up the Ramp" mode. An observation consists in a series of short (1-2 minutes) exposures during which the pixels are read out every 1.3 second, while continuously accumulating charges proportionally to the received flux. We discuss here the preprocessing of CAGIRE data and a method that can be used to recover the flux received by each pixel from the slope of the ramp

Testing the 10 spectrograph units for DESI: approach and results

International audienceThe recently commissioned Dark Energy Spectroscopic Instrument (DESI) will measure the expansion history of theUniverse using the Baryon Acoustic Oscillation technique.The spectraof 35 million galaxies and quasars over 14000 sqdeg will be measuredduring the life of the experiment.A new prime focus corrector for theKPNOMayall telescope delivers light to 5000 fiber optic positioners.The fibers in turn feed ten broad-band spectrographs.A consortium of Aix-Marseille University (AMU) and CNRS laboratories (LAM, OHP and CPPM) together with LPNHE (CNRS, IN2P3, Sorbonne Université and Université de Paris) and the WINLIGHT Systems company based in Pertuis (France), were in charge of integrating and validating the performance requirements of the ten full spectrographs, equipped with their cryostats, shutters and other mechanisms. We present a summary of our activity which allowed an efficient validation of the systems in a short-time schedule. We detail the main results. We emphasize the benefits of our approach and also its limitations

LISA AIVT Optical Ground Support Equipement technology developments

International audienceThe LISA space interferometer aims at GW detection with »3x10-20/√Hz strain sensitivity, resulting in a displacement sensitivity of 11pm/√Hz over a path length of 2.5x109 m in the frequency range from 3x10-5 to 1 Hz.The LISA France Collaboration is in charge of the ground optical tests of the MOSA (Moving Optical Sub-Assembly), including the Optical Bench, Telescope and Gravitational Reference Sensor. Special check-out equipment is required, such as the Far-Field Optical Ground Support Equipment aiming at measuring the Tilt-To-Length coupling coefficient between angular residual beam jitter and longitudinal path length. The FF-OGSE simulates the incoming jittering beam and measures the associated longitudinal path length change.We present two prototypes – the Zerodur InterFerOmeter and the TTL-OB - that will demonstrate the optical performance, the functional tests, the limits on sensitivity and the precision of the path length measurements achievable on-ground. These two benches are the first part of the design and specification for the FF-OGSE.The Stray Light OGSE aims at stray light characterization in the integrated MOSA. It measures and identifies, separately, the different sources of stray light through the measurement of the corresponding fringe patterns while scanning the laser’s optical frequency

LISA AIVT Optical Ground Support Equipement technology developments

International audienceThe LISA space interferometer aims at GW detection with »3x10-20/√Hz strain sensitivity, resulting in a displacement sensitivity of 11pm/√Hz over a path length of 2.5x109 m in the frequency range from 3x10-5 to 1 Hz.The LISA France Collaboration is in charge of the ground optical tests of the MOSA (Moving Optical Sub-Assembly), including the Optical Bench, Telescope and Gravitational Reference Sensor. Special check-out equipment is required, such as the Far-Field Optical Ground Support Equipment aiming at measuring the Tilt-To-Length coupling coefficient between angular residual beam jitter and longitudinal path length. The FF-OGSE simulates the incoming jittering beam and measures the associated longitudinal path length change.We present two prototypes – the Zerodur InterFerOmeter and the TTL-OB - that will demonstrate the optical performance, the functional tests, the limits on sensitivity and the precision of the path length measurements achievable on-ground. These two benches are the first part of the design and specification for the FF-OGSE.The Stray Light OGSE aims at stray light characterization in the integrated MOSA. It measures and identifies, separately, the different sources of stray light through the measurement of the corresponding fringe patterns while scanning the laser’s optical frequency

LISA AIVT Optical Ground Support Equipement technology developments

International audienceThe LISA space interferometer aims at GW detection with »3x10-20/√Hz strain sensitivity, resulting in a displacement sensitivity of 11pm/√Hz over a path length of 2.5x109 m in the frequency range from 3x10-5 to 1 Hz.The LISA France Collaboration is in charge of the ground optical tests of the MOSA (Moving Optical Sub-Assembly), including the Optical Bench, Telescope and Gravitational Reference Sensor. Special check-out equipment is required, such as the Far-Field Optical Ground Support Equipment aiming at measuring the Tilt-To-Length coupling coefficient between angular residual beam jitter and longitudinal path length. The FF-OGSE simulates the incoming jittering beam and measures the associated longitudinal path length change.We present two prototypes – the Zerodur InterFerOmeter and the TTL-OB - that will demonstrate the optical performance, the functional tests, the limits on sensitivity and the precision of the path length measurements achievable on-ground. These two benches are the first part of the design and specification for the FF-OGSE.The Stray Light OGSE aims at stray light characterization in the integrated MOSA. It measures and identifies, separately, the different sources of stray light through the measurement of the corresponding fringe patterns while scanning the laser’s optical frequency