Calibration Campaign Research Articles

Radiometric calibration of AVIRIS-NG sensor using Indian desert sites

This manuscript describes reflectance-based vicarious calibration exercise of the Airborne Visible InfraRed Imaging Spectrometer - Next Generation (AVIRIS-NG) sensor during its second phase of observation campaigns over the Indian subcontinent. Vicarious calibration methods are one of the significant approaches that have been practiced successfully for the absolute radiometric calibration of various spaceborne and airborne sensors to ascertain its desired performance in terms of data quality and its accuracy. Calibration campaigns were performed for AVIRIS-NG sensor during its phase-2 campaign overpass at the Desalpar (25th March 2018) and Amarapur (27th March 2018) calibration sites of Gujarat, India. Results from ground-based measurements of atmospheric conditions and surface reflectance including descriptions of the test sites are summarized in this work. Based on the in-situ data and images from the AVIRIS-NG sensor, the at-sensor apparent radiances are simulated using the 6SV radiative transfer model. The comparison shows good agreement between AVIRIS-NG measured radiance and 6SV simulated apparent radiance at the two calibration sites using desert aerosol model. The gains (spectrally) derived agree to within ∼ 2 % each other. Furthermore, an analysis is performed to determine or identify systematic and random errors, and the overall uncertainty is evaluated for reflectance-based method (total uncertainty of less than 4 % spectrally).

Air-to-Ground Transmission and Near Real-Time Visualization of FBG Sensor Data via Cloud Database

During the last decades, innovative aircraft health management systems have been receiving increasing interest from original equipment manufacturers (OEMs) and aircraft operators. Their implementation could lead to substantial benefits: drastic cuts in turnaround time, operation costs, and life cycle costs (LCCs) as well as sharp increases in system availability, safety, and reliability. An interconnectivity step-up is, hence, needed to guarantee a seamless data transfer. In this article, an integrated open-source solution for reliable data transmission and near real-time graphical visualization is proposed. After a comprehensive calibration and verification campaign performed on a test stand, the overall system has been successfully validated on structural data measured using a network of fiber Bragg gratings (FBGs) mounted on a radio-controlled model aircraft. The result is an effective and robust system able to monitor near real-time critical parameters and health status of structures. With this system, the temperature and displacements of the structure can be displayed on a heat map arranged on a 3-D model and visualized through a computer application on the ground. The proposed methodology can be applied to heterogeneous scenarios, ranging from maintenance planning activities to performance checks, providing an all-in-one solution for flight data management as well as other applications in the structural monitoring domain.

Absolute Radiometric Calibration of ZY3-02 Satellite Multispectral Imager Based on Irradiance-Based Method

In this paper, an irradiance-based absolute radiometric calibration campaign at Baotou calibration site during June and July 2018 was described. This radiometric calibration campaign made use of six radiometric calibration tarps. The synchronous measurements of parameters such as surface reflectance, atmospheric parameters, and diffuse-to-global irradiance ratio were collected at the satellite overpass. The top-of-atmospheric radiance was predicted by radiative transfer model with these synchronous measurements. The linear relationship between DNs of satellite sensor and band-specific top-of-atmospheric spectral radiance was established, and a stable and reliable absolute calibration coefficient of ZY3-02 MUX was determined in this campaign. We compared the calibration results of the irradiance-based method with those of the reflectance-based method. The results suggested that the irradiance-based method is better than reflectance-based method.

The pre-launch on-ground characterization of Mars Multispectral Imager for Subsurface Studies (Ma_MISS) spectrometer for ExoMars rover mission: Spectral calibration.

The Ma_MISS spectrometer is integrated within the drilling system of the Rosalind Franklin ExoMars rover. This paper reports the on-ground calibration campaign performed on the spectrometer. Here, we focus on the spectral calibration of the instrument. The experimental setup used to carry out calibration is described, and the methods used for data processing and key parameters retrieval are explained. In particular, the spectral parameters such as (i) pixel central wavelengths, (ii) spectral response function, (iii) spectral resolution, (iv) sampling, and (v) range are determined. In a follow-up paper, the linearity and radiometric calibrations are described, while in De Sanctis etal. [Planet. Sci. J. 3, 142 (2022)], the validation of spectral measurements performed on synthetic and natural rock targets is presented.

MEDA HS: Relative humidity sensor for the Mars 2020 Perseverance rover

The Finnish Meteorological Institute (FMI) provides a relative humidity measurement sensor (HS) for NASA's Mars 2020 rover. The sensor is a part of the Mars Environmental Dynamic Analyzer (MEDA), a suite of environmental sensors provided by Spain's Centro de Astrobiología. The main scientific goal of the humidity sensor is to measure the relative humidity of the Martian atmosphere near the surface and to complement previous Mars mission atmospheric measurements for a better understanding of Martian atmospheric conditions and the hydrological cycle. Relative humidity has been measured from the surface of Mars previously by Phoenix and Curiosity. Compared to the relative humidity sensor on board Curiosity, the MEDA HS is based on a new version of the polymeric capacitive humidity sensor heads developed by Vaisala. Calibration of humidity devices for Mars conditions is challenging and new methods have been developed for MEDA HS. Calibration and test campaigns have been performed at the FMI, at University of Michigan and the German Aerospace Center (DLR) in Berlin to achieve the best possible calibration. The accuracy of HS and uncertainty of the calibration has been also analysed in detail with VTT Technical Research Centre of Finland. Assessment of sensor performance after landing on Mars confirms that the calibration has been successful, and the HS is delivering high quality data for the science community.

Calorimeter calibration of the ComPol CubeSat gamma-ray polarimeter

ComPol is a proposed CubeSat mission dedicated to long-term study of gamma-ray polarisation of astrophysical objects. Besides spectral and timing measurements, polarisation analysis can be a powerful tool in constraining current models of the geometry, magnetic field structure and acceleration mechanisms of different astrophysical sources. The ComPol payload is a Compton telescope optimised for polarimetry and consists of a 2 layer stacked detector configuration. The top layer, the scatterer, is a Silicon Drift Detector matrix developed by the Max Planck Institute for Physics and Politecnico di Milano. The second layer is a calorimeter consisting of a CeBr3 scintillator read-out by silicon photo-multipliers developed at CEA Saclay. This paper presents the results of the prototype calorimeter calibration campaign, executed in March 2022 at IJCLab Orsay and simulations of the expected performance of the polarimeter using updated performance figures of the detectors.

Calorimetry in a Neutrino Observatory: The JUNO Experiment

The Jiangmen Underground Neutrino Observatory (JUNO) is a multipurpose experiment under construction in southern China; detector completion is expected in 2023. JUNO is a homogeneous calorimeter consisting of a target mass of 20 kt of an organic liquid scintillator, aiming to detect antineutrinos from reactors to investigate the neutrino oscillation mechanism. The scintillation and Cerenkov light emitted after the interaction of antineutrinos with the liquid scintillator is seen by a compound system of 20 inch large PMTs and 3 inch small PMTs, with a total photo-coverage of 78%. A dual-calorimetry technique is developed based on the presence of the two independent photosensor systems which are characterized by different average light level regimes, resulting in different dynamic ranges. Thanks to this novel technique, an unprecedented high light yield, and in combination with a comprehensive multiple-source and multi-position calibration campaign, JUNO is expected to reach energy-related systematic uncertainties below 1% and an effective energy resolution of 3% at 1%, required for the neutrino oscillation analysis.

Calibration of the IXPE Focal Plane X-Ray Polarimeters to Polarized Radiation

The Imaging X-ray Polarimetry Explorer (IXPE) is a NASA Small Explorer mission—in partnership with the Italian Space Agency—dedicated to X-ray polarimetry in the 2–8 keV energy band. The IXPE telescope comprises three grazing incidence mirror modules coupled to three detector units hosting each one a Gas Pixel Detector, a gas detector that allows measuring the polarization degree by using the photoelectric effect. A wide and accurate ground calibration was carried out on the IXPE Detector Units at INAF-IAPS, in Italy, where a dedicated facility was setup at this aim. In this paper, we present the results obtained from this calibration campaign to study the IXPE focal plane detector response to polarized radiation. In particular, we report on the modulation factor, which is the main parameter to estimate the sensitivity of a polarimeter.

Initial results of the TUBIN small satellite mission for wildfire detection

TUBIN is a microsatellite mission tasked with the demonstration of microbolometer technology for the detection of high-temperature events. To this end, the spacecraft employs a set of two microbolometers sensitive in the thermal range of the electromagnetic spectrum as well as a complementary CMOS-based imager for the visible spectrum. Additionally, the mission serves to demonstrate the upgraded capabilities of the TUBiX20 microsatellite platform after its initial implementation within the TechnoSat mission, launched in 2017. Here, the platform was upgraded with star trackers for enhanced attitude determination to enable the pointing accuracy required by the mission. Launched in June 2021, TUBIN has already successfully detected wildfires and volcanic activity in different biomes across the globe. Additionally, the sensor suite of the TUBIN mission was applied to examine its capabilities in the assessment of light-pollution in dedicated night time imaging campaigns. In this paper, we present and analyze data sets captured in the first six months of operation to illustrate capabilities, accomplishments, and challenges regarding payload operation, calibration, and data analysis for the TUBIN mission. Finally, the plans for the second half of TUBIN’s nominal lifetime are outlined, including an on-orbit calibration campaign and increased automation in payload operations.

Calibration of ground surface albedo models

The emergence of bifacial photovoltaics as a serious option for large-scale power generation makes the accuracy of the in-situ estimation of ground surface albedo increasingly critical. Recent studies have evaluated the performance of different models but an investigation of how these models should be calibrated is missing. This paper proposes geographically generalised parametrisations for time-variant albedo models of vegetated and desert surfaces based on a worldwide database and reports their performance compared to site-specific, unbiased parametrisations. These geographically generalised formulations can be used as an alternative for lengthy calibration campaigns as their only parameters can be easily measured. The paper also presents a simple method for deriving white-sky albedo without the need for diffuse irradiance data. The method is founded both theoretically and empirically. If on-site measurements can be collected to calibrate a model, the duration of the campaign is usually a few weeks at the maximum. This paper first shows evidence of the strong impact of the timing on calibration performance and accordingly gives practical guidelines on the most suitable measurement seasons and weather conditions. In general, early-summer months appear to be the most appropriate time for calibrating most models. Atmospheric turbidity during the campaign period, however, should be either minimised or maximised depending on the site and the model. Finally, in case no flexibility exists in timing the calibration, simple models with few parameters should be deployed. Geometric mean shows the most robust performance at most sites.

QUBIC I: Overview and science program

The Q & U Bolometric Interferometer for Cosmology (QUBIC) is a novel kind of polarimeter optimized for the measurement of the B-mode polarization of the Cosmic Microwave Background (CMB), which is one of the major challenges of observational cosmology. The signal is expected to be of the order of a few tens of nK, prone to instrumental systematic effects and polluted by various astrophysical foregrounds which can only be controlled through multichroic observations. QUBIC is designed to address these observational issues with a novel approach that combines the advantages of interferometry in terms of control of instrumental systematic effects with those of bolometric detectors in terms of wide-band, background-limited sensitivity. The QUBIC synthesized beam has a frequency-dependent shape that results in the ability to produce maps of the CMB polarization in multiple sub-bands within the two physical bands of the instrument (150 and 220 GHz). These features make QUBIC complementary to other instruments and makes it particularly well suited to characterize and remove Galactic foreground contamination. In this article, first of a series of eight, we give an overview of the QUBIC instrument design, the main results of the calibration campaign, and present the scientific program of QUBIC including not only the measurement of primordial B-modes, but also the measurement of Galactic foregrounds.We give forecasts for typical observations and measurements: with three years of integration on the sky and assuming perfect foreground removal as well as stable atmospheric conditions from our site in Argentina, our simulations show that we can achieve a statistical sensitivity to the effective tensor-to-scalar ratio (including primordial and foreground B-modes) σ(r)=0.015.

On-ground and on-orbit time calibrations of GECAM

ABSTRACT High time resolution and accuracy are of critical importance in the studies of timing analysis and time delay localization of gamma-ray bursts (GRBs), soft gamma-ray repeaters (SGRs) and pulsars. The Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor (GECAM) consisting of two micro-satellites, GECAM-A and GECAM-B, launched on 2020 December 10, is aimed at monitoring and locating X-ray and GRBs all over the sky. To achieve its scientific goals, GECAM is designed to have the highest time resolution (0.1 $\mu {\rm s}$) among all GRB detectors ever flown. Here, we make a comprehensive time calibration campaign including both on-ground and on-orbit tests to derive not only the relative time accuracy of GECAM satellites and detectors, but also the absolute time accuracy of GECAM-B. Using the on-ground calibration with a $\rm ^{22}Na$ radioactive source, we find that the relative time accuracy between GECAM-A and GECAM-B is about 0.15 $\mu {\rm s}$ (1σ). To measure the relative time accuracy between all detectors of a single GECAM satellite, cosmic-ray events detected on orbit are utilized since they could produce many secondary particles simultaneously record by multiple detectors. We find that the relative time accuracy among all detectors onboard GECAM-B is about 0.12 $\mu {\rm s}$ (1σ). Finally, we use the novel Li-CCF method to perform the absolute time calibration with Crab pulsar and SGR J1935+2154, both of which were jointly observed by GECAM-B and Fermi/GBM, and obtain that the time difference between GECAM-B and Fermi/GBM is 3.06 ± 6.04 $\mu {\rm s}$ (1σ).

Characterization of OSL dosimeters used at the ELI-beamlines laser-driven accelerator facility

The Extreme Light Infrastructure (ELI) Beamlines laser-driven accelerator facility is set to operate the most intense non-military laser system in the world, with ultra-high power up to 10 PW, concentrated plasma intensities of up to 1024 W cm−2, and ultra-short laser pulses of the order of few femtoseconds. A robust and redundant radiation monitoring system is in place to minimise risks to personnel and general public. Beryllium oxide optically stimulated luminescence (BeO-OSL) detectors are used to monitor radiation levels in the experimental building and surrounding grounds. In fact, in recent years, BeO-OSL have become an increasingly more popular choice for personal and environmental dosimetry. At ELI Beamlines, an exhaustive and thorough characterization process of the BeO-OSLs is in place. Dosimeter responses are studied as a function of delivered air kerma and photon energies. Calibration curves are calculated. Results from the latest calibration campaign are presented.

3MI EM on-ground calibration

The Multi-viewing, Multi-spectral, Multi-polarisation Imager (3MI) is one of the payloads that will be on board of the MetOp-SG “Satellite A”, developed to provide information on atmospheric aerosols. 3MI is a space-based, wide field-of-view polarimeter that is designed to acquire sequential images of the same ground target, which are then combined with multiple spectral views in both un-polarized and polarized channels. This article presents the on-ground calibration approach for the 3MI payload. The calibration methodology starts from the challenging high level specifications down to the specification of adequate Key Data Parameters (KDP) introduced in an instrument model. An error budget allows to evaluate the required accuracy on each KDP and, consequently, to specify the needed Ground System Equipments for the calibration. Preliminary test results of the EM calibration campaign are also discussed.

Airborne lidar observations of wind, water vapor, and aerosol profiles during the NASA Aeolus calibration and validation (Cal/Val) test flight campaign

Abstract. Lidars are uniquely capable of collecting high-precision and high spatiotemporal resolution observations that have been used for atmospheric process studies from the ground, aircraft, and space for many years. The Aeolus mission, the first space-borne Doppler wind lidar, was developed by the European Space Agency (ESA) and launched in August 2018. Its novel Atmospheric LAser Doppler INstrument (ALADIN) observes profiles of the component of the wind vector and aerosol/cloud optical properties along the instrument's line-of-sight (LOS) direction on a global scale. A total of two airborne lidar systems have been developed at NASA Langley Research Center in recent years that collect measurements in support of several NASA Earth Science Division focus areas. The coherent Doppler Aerosol WiNd (DAWN) lidar measures vertical profiles of LOS velocity along selected azimuth angles that are combined to derive profiles of horizontal wind speed and direction. The High Altitude Lidar Observatory (HALO) measures high resolution profiles of atmospheric water vapor (WV) and aerosol and cloud optical properties. Because there are limitations in terms of spatial and vertical detail and measurement precision that can be accomplished from space, airborne remote sensing observations like those from DAWN and HALO are required to fill these observational gaps and to calibrate and validate space-borne measurements. Over a 2-week period in April 2019, during their Aeolus Cal/Val Test Flight campaign, NASA conducted five research flights over the eastern Pacific Ocean with the DC-8 aircraft. The purpose was to demonstrate the following: (1) DAWN and HALO measurement capabilities across a range of atmospheric conditions, (2) Aeolus Cal/Val flight strategies and comparisons of DAWN and HALO measurements with Aeolus, to gain an initial perspective of Aeolus performance, and (3) ways in which atmospheric dynamic processes can be resolved and better understood through simultaneous observations of wind, WV, and aerosol profile observations, coupled with numerical model and other remote sensing observations. This paper provides a brief description of the DAWN and HALO instruments, discusses the synergistic observations collected across a wide range of atmospheric conditions sampled during the DC-8 flights, and gives a brief summary of the validation of DAWN, HALO, and Aeolus observations and comparisons.

X-ray transmission calibration of the gate valve for the x-ray astronomy satellite XRISM

Resolve onboard the x-ray satellite X-Ray Imaging and Spectroscopy Mission (XRISM) is a cryogenic instrument with an x-ray microcalorimeter in a Dewar. A lid partially transparent to x-rays (called gate valve or GV) is installed at the top of the Dewar along the optical axis. Because observations will be made through the GV for the first few months, the x-ray transmission calibration of the GV is crucial for initial scientific outcomes. We present the results of our ground calibration campaign of the GV, which is composed of a Be window and a stainless steel mesh. For the stainless steel mesh, we measured its transmission using the x-ray beamline at ISAS. For the Be window, we used synchrotron facilities to measure the transmission and modeled the data with (i) photoelectric absorption and incoherent scattering of Be, (ii) photoelectric absorption of contaminants, and (iii) coherent scattering of Be changing at specific energies. We discuss the physical interpretation of the transmission discontinuity caused by the Bragg diffraction in polycrystal Be, which we incorporated into our transmission phenomenological model. We present the x-ray diffraction measurement on the sample to support our interpretation. The measurements and the constructed model meet the calibration requirements of the GV. We also performed a spectral fitting of the Crab nebula observed with Hitomi SXS and confirmed improvements of the model parameters.

Calibration study of the Gamma-Ray Monitor onboard the SVOM satellite

The Gamma-Ray Monitor (GRM), which is one of the four main scientific instruments onboard the Space-based multi-band astronomical Variable Objects Monitor (SVOM) satellite, is dedicated to the spectrum measurement and study of Gamma-Ray Bursts (GRBs) in the 15 keV to 5 MeV energy band, as well as to perform real-time triggering and localization of the transient bursts in orbit. In order to fully understand the performance of the developed spectrometer and optimize the calibration scheme for the flight model (FM), several calibration campaigns, such as energy–channel relation and energy resolution, detection efficiency, temperature response, high-voltage effect and the non-uniformity tests of detector crystal, have been implemented during the development phase of the qualification model (QM) of GRM, utilizing radionuclides, hard X-ray beam and synchrotron radiation facility. The data analysis results show good agreement with the expected output by Monte Carlo simulations. The detailed optimization scenario for FM calibration is also presented in this paper.

Towards an Occupancy-Oriented Digital Twin for Facility Management: Test Campaign and Sensors Assessment

This study focuses on calibration and test campaigns of an IoT camera-based sensor system to monitor occupancy, as part of an ongoing research project aiming at defining a Building Management System (BMS) for facility management based on an occupancy-oriented Digital Twin (DT). The research project aims to facilitate the optimization of building operational stage through advanced monitoring techniques and data analytics. The quality of collected data, which are the input for analyses and simulations on the DT virtual entity, is critical to ensure the quality of the results. Therefore, calibration and test campaigns are essential to ensure data quality and efficiency of the IoT sensor system. The paper describes the general methodology for the BMS definition, and method and results of first stages of the research. The preliminary analyses included Indicative Post-Occupancy Evaluations (POEs) supported by Building Information Modelling (BIM) to optimize sensor system planning. Test campaign are then performed to evaluate collected data quality and system efficiency. The method was applied on a Department of Politecnico di Milano. The period of the year in which tests are performed was critical for lighting conditions. In addition, spaces’ geometric features and user behavior caused major issues and faults in the system.Incorrect boundary definition: areas that are not covered by boundaries; thus, they are not monitored

Energy calibration of ion-beam accelerators with neutron and gamma nuclear reactions between 2 MeV and 4 MeV

The accurate knowledge of the beam energy is of first importance in most applications using ion beams delivered by electrostatic accelerators. Regular beam energy calibration is thus required. The standard procedure is to use neutron thresholds and well known gamma-ray resonances. However, only a few calibration points are available between 2 MeV and 4 MeV despite the need of such beam energies, for instance, for nuclear reaction analyses.In this work, the suitability of 27Al(p,γ)28Si and 45Sc(p,n)45Ti resonances has been studied in this specific energy range by comparison with well-established calibration energies. The methodology used for the experiments and data treatment is fully detailed.The usefulness of these resonances is shown through several calibration campaigns that led to a complete energy calibration of two accelerator based facilities from 500 keV up to 4 MeV.

In-Orbit Calibration and Validation of HY-2B Altimeter Using an Improved Transponder

HY-2B (Haiyang) is the follow-on mission to HY-2A, the Chinese first sea satellite for oceanography, launched in October 2018. The main payloads onboard are similar to HY-2A. For the altimeter, an in-orbit calibration mode was designed to achieve higher calibration precision. An improved transponder was built and deployed for the calibration campaign. The purpose of this article is to describe the in-orbit calibration and validation of HY-2B altimeter based on an improved transponder. A signal-rebuilt transponder was developed and employed in HY-2A altimeter calibration. It played an important role in the quantitative analysis of HY-2A altimeter data products. For HY-2B altimeter, a newly designed calibration mode was added, and an improved transponder was built. It has some advantages over the previous one in the rebuilt signal forms and modulation ways. Two calibration campaigns were carried out, in April 2019 and October 2020 at different sites. In the two campaigns, the precision of the altimeter range calibration is obtained less than 1 cm. For further validation and assessment of the result, a comparison between HY-2B and Jason-3 was performed in terms of sea surface height on the tens of cross track points in the open ocean. The comparison result shows high degree of accuracy and stability of HY-2B altimeter instrument. In China's next five-year plan (2021–2025), many more transponders and related calibration facilities would be installed in the ocean calibration fields, serving a variety of different satellite altimetry missions.