Experimental Astronomy最新文献

In the gamma range, polarization detection is particularly difficult. For example, the registration of linear polarization can help in determining the structure of the magnetic field in a jet when generating radiation in gamma-ray bursts. The measurement of linear polarization in the 511 keV line associated with the annihilation of electrons and positrons may be an indicator of the asymmetry of the distribution of radioactive nickel in the scattering shell of Supernovae. The principle of detecting the polarization of gamma radiation is based on the anisotropy of Compton scattering. This property can be used in the development of polarimeters, which are a segmented scintillation detector. The paper presents polarization calibrations for 3 BGO detectors, which are a simplified prototype of a segmented gamma-ray spectrometer (SGS) being developed for the Chibis-AI microsatellite. The complete assembly of the SGS detector consists of 32 BGO bars. Polarization calibrations of the SGS prototype in the 511 keV line were carried out at the experimental facility at the Institute for Nuclear Research of the Russian Academy of Sciences using the isotope (^{22}text {Na}). Also, for comparison, a simulation of the registration of linear polarization was carried out using the Geant4 software package. The experimental results agree withing (2sigma ) of simulations.

The term “asteroid family” refers to a collection of asteroids that share similar proper orbital elements such as semi-major axis, eccentricities, and orbital inclinations. Detecting small asteroid families has proved to be a challenge for a long time because of their extremely low sample size. In general, standalone machine learning classifiers tend to exhibit a bias towards classes with larger sample sizes, resulting in the inadequate classification of asteroid families with limited data. In this paper, a two-step supervised model was proposed for the effective classification of the asteroid families, especially for the tiny, small, and lower groups of medium asteroid families. The proposed model uses two-step classification in an attempt to resolve the challenges that come with the imbalanced dataset where at first a binary classification of small and large families was done with an XGB (Extreme Gradient boosting) classifier and then in the second stage Random Forest classifier was used alongside previously identified binary features to classify asteroid families. The proposed model performed better with higher F1 scores for tiny and small asteroid families compared to other algorithms tested in this work. It also achieved a perfect F1 score for 90 families, among 112 families which were tested. As for the lower group of medium sized asteroid families, it performed slightly worse compared to the previously used machine learning algorithms. Along with this, four dataset imbalance handling techniques have been employed in this work and compared to the proposed algorithm.

As a study relevant to the ESA’s “Voyage 2050” programme, we present an ambitious L-class mission concept aimed at exploring one of the most intriguing bodies in the Solar System – Titan, Saturn’s largest moon. Titan is a planet-like moon rich in organic compounds and features complex interactions between its interior, surface, and atmosphere, similar to those seen on Earth. Additionally, Titan is one of the few places in the Solar System with the highest potential for eventual habitability. Despite the groundbreaking discoveries made by the Cassini-Huygens mission, Titan still holds many mysteries that demand further exploration using more advanced technologies and diverse exploration vehicles. Our proposed mission, named TARA (Titan Atmospheric Research Ascendant), aims to conduct both orbital and in situ investigations of Titan, surpassing the scientific and technological achievements of Cassini-Huygens. TARA would provide comprehensive and close-up exploration of Titan over extended periods, utilizing capabilities that were previously unattainable. The mission architecture consists of two primary components: an orbiter equipped with an extensive suite of instruments that would orbit Titan, ideally in a low-eccentricity circular polar orbit, and an ornithopter equipped with a set of in situ exploration elements, both aimed to study Titan’s atmospheric dynamics and the evolution of pre-biotic environment. The ideal mission timeline would target an arrival at Titan just before its next northern Spring equinox in 2039, a period of heightened activity for observing Titan’s still poorly understood seasonal atmospheric and surface changes. TARA’s focus on Titan’s northern latitudes would complement NASA’s upcoming Dragonfly mission, which is scheduled to explore Titan’s equatorial regions in the mid-2030s. Together, these missions would provide comprehensive temporal, spatial, and scientific coverage of this fascinating moon.

We present an investigation into the effects of high-energy proton damage on charge trapping in germanium cross-strip detectors with the goal of accomplishing three important measurements. First, we calibrated and characterized the spectral resolution of a spare COSI-balloon detector in order to determine the effects of intrinsic trapping, finding that electron trapping due to impurities dominates over hole trapping in the undamaged detector. Second, we performed two rounds of proton irradiation of the detector in order to quantify, for the first time, the rate at which charge traps are produced by proton irradiation. We find that the product of the hole trap density and cross-sectional area, ([nsigma ]_textrm{h}), follows a linear relationship with the proton fluence, (F_textrm{p}), with a slope of ((5.4pm 0.4)times 10^{-11},mathrm {cm/p^{+}}). Third, by utilizing our measurements of physical trapping parameters, we performed calibrations which corrected for the effects of trapping and mitigated degradation to the spectral resolution of the detector.

ExoSim 2 is the next generation of the Exoplanet Observation Simulator (ExoSim) tailored for spectro-photometric observations of transiting exoplanets from space, ground, and sub-orbital platforms. This software is a complete rewrite implemented in Python 3, embracing object-oriented design principles, which allow users to replace each component with their functions when required. ExoSim 2 is publicly available on GitHub, serving as a valuable resource for the scientific community. ExoSim 2 employs a modular architecture using Task classes, encapsulating simulation algorithms and functions. This flexible design facilitates the extensibility and adaptability of ExoSim 2 to diverse instrument configurations to address the evolving needs of the scientific community. Data management within ExoSim 2 is handled by the Signal class, which represents a structured data cube incorporating time, space, and spectral dimensions. The code execution in ExoSim 2 follows a three-step workflow: the creation of focal planes, the production of Sub-Exposure blocks, and the generation of non-destructive reads (NDRs). Each step can be executed independently, optimizing time and computational resources. ExoSim 2 has been extensively validated against other tools like ArielRad and has demonstrated consistency in estimating photon conversion efficiency, saturation time, and signal generation. The simulator has also been validated independently for instantaneous read-out and jitter simulation, and for astronomical signal representation. In conclusion, ExoSim 2 offers a robust and flexible tool for exoplanet observation simulation, capable of adapting to diverse instrument configurations and evolving scientific needs. Its design principles and validation results underscore its potential as a valuable resource in the field of exoplanet research.

We detail the REACH radiometric system designed to enable measurements of the 21-cm neutral hydrogen line. Included is the radiometer architecture and end-to-end system simulations as well as a discussion of the challenges intrinsic to highly-calibratable system development. Following this, we share laboratory results based on the calculation of noise wave parameters utilising an over-constrained least squares approach. For five hours of integration on a custom-made source with comparable impedance to that of the antenna used in the field, we demonstrate a calibration RMSE of 80 mK. This paper therefore documents the state of the calibrator and data analysis in December 2022 in Cambridge before shipping to South Africa.

Position calibration in the deep sea is typically done by means of acoustic multilateration using three or more acoustic emitters installed at known positions. Rather than using hydrophones as receivers that are exposed to the ambient pressure, the sound signals can be coupled to piezo ceramics glued to the inside of existing containers for electronics or measuring instruments of a deep sea infrastructure. The ANTARES neutrino telescope operated from 2006 until 2022 in the Mediterranean Sea at a depth exceeding 2000 m. It comprised nearly 900 glass spheres with 432 mm diameter and 15 mm thickness, equipped with photomultiplier tubes to detect Cherenkov light from tracks of charged elementary particles. In an experimental setup within ANTARES, piezo sensors have been glued to the inside of such – otherwise empty – glass spheres. These sensors recorded signals from acoustic emitters with frequencies from 46545 to 60235 Hz. Two waves propagating through the glass sphere are found as a result of the excitation by the waves in the water. These can be qualitatively associated with symmetric and asymmetric Lamb-like waves of zeroth order: a fast (early) one with (varvec{v_e approx 5,{textbf {mm}}/mu text {s}}) and a slow (late) one with (varvec{v_ell approx ,2,{textbf {mm}}/mu text {s}}). Taking these findings into account improves the accuracy of the position calibration. The results can be transferred to the KM3NeT neutrino telescope, currently under construction at multiple sites in the Mediterranean Sea, for which the concept of piezo sensors glued to the inside of glass spheres has been adapted for monitoring the positions of the photomultiplier tubes.

CATCH-1, as the first satellite of Chasing All Transients Constellation Hunters (CATCH) space mission, was successfully launched into its expected orbit on June 22, 2024. The flight model underwent environmental tests before launch, including thermal cycling, thermal vacuum, and mechanical evaluations. The CATCH-1 detector system is equipped with a 4-pixel Silicon Drift Detector (SDD) array. To ensure the reliability and redundancy of the CATCH-1 detector system, two sets of data acquisition systems were independently designed and calibrated. Our focus is on presenting the ground calibration results of CATCH-1, which demonstrate a strong linear correlation between energy and channel. The main data acquisition system achieves an energy resolution of (sim ) 120 eV@4 keV, while the backup data acquisition system has a slightly lower energy resolution of around 150 eV@4 keV, both meeting the design requirement of (le ) 160 eV@4 keV. Additionally, the time resolution is ( sim 4,mu s), complying with the design requirement of (le 10,mu s). The calibration database now includes the ground calibration results of CATCH-1, establishing a dependable basis for future data analysis. The development experience, calibration, and test results of this detector system will also provide a solid foundation for subsequent tasks such as CATCH-2.

This study analyzes twelve years of wind speed and direction data collected at the proposed National Large Solar Telescope (NLST) site near Pangong Tso, Merak village, Leh-Ladakh. A weather station from Campbell Scientific Instruments, installed in 2008, has been continuously monitoring meteorological parameters, including wind speed and direction. The data reveals a consistent pattern of predominantly northwest winds, particularly during morning hours, with speeds generally below 5 m/s. While seasonal variations influence wind speed and direction, the overall trend remains stable. To assess the site’s suitability for astronomical observations, we compared high-altitude wind speeds at various renowned astronomical sites using reanalysis data from 2008 to 2020. Strong correlations were observed between surface and high-altitude wind speeds at 10 m, 50 m, and 500 m. Statistical analysis of 200-mbar pressure level wind speeds identified La Palma as the most favorable site with a wind speed of 18.76 m/s. La Silla, on the other hand, exhibited the highest wind speed at 34.76 m/s. Merak’s estimated wind speed of 30.99 m/s, coupled with its favorable wind direction and low surface wind speeds, suggests its potential as a promising site for astronomical observations.

The Solar Ultraviolet Imaging Telescope (SUIT ) on board the Aditya-L1 mission is designed to observe the Sun across 200–400 nm wavelength. The telescope used 16 dichroic filters tuned at specific wavelengths in various combinations to achieve its science goals. For accurate measurements and interpretation, it is important to characterize these filters for spectral variations as a function of spatial location and tilt angle. Moreover, we also measured out-of-band and in-band transmission characteristics with respect to the inband transmissions. In this paper, we present the experimental setup, test methodology, and the analyzed results. Our findings reveal that the transmission properties of all filters meet the expected performance for spatial variation of transmission and the transmission band at a specific tilt angle. The out-of-band transmission for all filters is below 1% with respect to in-band, except for filters BB01 and NB01. These results confirm the capabilities of SUIT to effectively capture critical solar features in the anticipated layer of the solar atmosphere.