Astronomical Measurements Research Articles

Local Splines and the Least Squares Method

The least squares method is widely used in processing quantitative results of natural science experiments, technical data, astronomical and geodetic observations and measurements. This paper proposes the construction of a modified least squares method based on the use of basis splines of a non-zero level. This modification allows us to obtain a continuously differentiable (required number of times) solution to the problem. The resulting solution is convenient to use to further solve other related problems. The construction of a continuously differentiable solution and a twice continuously differentiable solution is considered in more detail. These solutions are constructed based on the use of basis Hermitian splines of the fourth and sixth orders of approximation. The numerical results are presented for processing inaccurately specified experimental data, as well as for smoothing curves.

Comparison of the Different Celestial Length Measurements Approaches: Trigonometric Parallax, Cepheids and Type Ia Supernovae

As a matter of fact, astronomical measurements are one of the important topics in astronomy especially in recent years, with significant implications for spacecraft navigation within the solar system, stellar modeling, cosmic scales as well as the evolution. On this basis, this study presents several existing measurement methods and provides detailed explanations of three commonly used methods, i.e., trigonometric parallax, cepheid, and type Ia supernovae. To be specific, the principles as well as instruments associated with these methods are detailly discussed and analyzed. According to the analysis, the typical observations as well as current state-of-art results are also presented. At the same time, the current limitations such as equipment resolution, model calibration, and differentiation of background galaxies are compared and clarified. Furthermore, the prospects for future updates and developments of new approaches are also explored in the meantime. Overall, these results shed light on guiding further exploration of length measurement for celestial.

Error Analysis for Rotating-drift-scan Charge-coupled Device Observation of Near-Earth Asteroids

The apparent velocities of near-Earth asteroids (NEAs) are usually high when they pass by Earth. Observing these fast-moving objects with long exposure times would cause their images to streak and significantly decrease the precision of astronomical measurements. The rotating-drift-scan (RDS) charge-coupled device technique is a promising approach to observe fast-moving NEAs during their close approaches to Earth. By rotating the camera of a telescope, an NEA can be observed in the time delay integration mode. This allows the asteroid to be imaged as a point source, even with a long exposure time. Here, we thoroughly present the RDS follow-up observation and orbit determination of a newly discovered NEA 2023 BJ7. This technique makes an impactful contribution to improving the NEA's orbit accuracy by extending the observation arc. A detailed statistical analysis of the astrometric error was conducted, revealing that RDS observations can achieve a competitive accuracy with an rms error of 0.″24 in right ascension and 0.″32 in declination. The instability of the telescope is thought to be the main reason affecting the internal precision. Furthermore, the RDS technique excels at observing fast-moving NEAs, as well as newly discovered NEAs without accurate ephemerides. For NEAs with rates of motion exceeding 10 deg day−1, the rms of RDS observation residuals is 0.″35 in the along-track direction and 0.″23 in the cross-track. With this technique, a network of small-aperture telescopes would substantially benefit our global NEAs monitoring system to ensure Earth’s safety from any asteroid impacts.

Constraining primordial black hole masses through f(R) gravity scalarons in Big Bang Nucleosynthesis

Big Bang Nucleosynthesis (BBN) is a strong probe for constraining new physics including gravitation. f(R) gravity theory is an interesting alternative to general relativity which introduces additional degrees of freedom known as scalarons. In this work we demonstrate the existence of black hole solutions in f(R) gravity and develop a relation between scalaron mass and black hole mass. We have used observed bound on the freezeout temperature to constrain scalaron mass range by modifying the cosmic expansion rate at the BBN epoch. The mass range of primordial black holes (PBHs) which are astrophysical dark matter candidates is deduced. The range of scalaron mass which does not spoil the BBN era is found to be 10-16–104 eV for both relativistic and non-relativistic scalarons. The window 10-16–10-14 eV of scalaron mass obtained from solar system constraint on PPN parameter is compatible with the BBN bound derived in this work. The PBH mass range is obtained as 106–10-14 M ⊙. Scalarons constrained by BBN are also eligible to accommodate axion like dark matter particles. The problem of ultra-light PBHs (M ≤ 10-24 M ⊙) not constrained by the present study of BBN is still open. Estimation of deuterium (D) fraction and relative D+3He abundance in the f(R) gravity scenario shows that the BBN history mimics that of general relativity. While the PBH mass range is eligible for non-baryonic dark matter, the BBN bounded scalarons provide with an independent strong field test of f(R) gravity. The PBH mass range obtained in the study is discussed in relation to future astronomical measurements.

HybPSF: Hybrid Point-spread Function Reconstruction for the Observed JWST NIRCam Image

The James Webb Space Telescope (JWST) marks a new era of astronomical observation and discovery, providing unrivaled precision in various measurements, including photometry, morphology, and shear measurement. Accurate point-spread function (PSF) models are essential for many of these measurements. In this paper, we introduce HybPSF, a hybrid PSF construction method for JWST NIRCam imaging data that combines the WebbPSF software, which simulates the PSF for JWST, with observed data to produce more accurate and reliable PSF models. We apply this method to the SMACS J0723 imaging data and construct supplementary structures from residuals obtained by subtracting the WebbPSF PSF model from the data. Our results show that HybPSF significantly reduces discrepancies between the PSF model and the data compared to WebbPSF. Specifically, the PSF shape parameter ellipticity and size comparisons indicate that HybPSF improves precision by approximately 10 times for R 2 and 50% for e. This improvement has important implications for astronomical measurements using JWST NIRCam imaging data.

SUBSTANTIATION OF THE RESULTS OF THE LASER LOCATION OF THE TRAJECTORY OF THE MOON MOVING AWAY FROM THE EARTH

Progress in astronomical measurements of the trajectories of the movement of celestial bodies reveals new effects that require justification. In particular, it refers to the slight drift of the Moon from the Earth. A solution to this problem is possible only based on an adequate mathematical model. To perform this, it was adapted Newton's law of universal gravitation to the case of moving masses in flat space and physical time. At the same time, the final speed of propagation of the gravitational field can be considered. The differential equations of motion of the three-mass Sun-Earth-Moon cosmic system are obtained. In the heliocentric coordinate system, transient processes of the movement of the named celestial bodies are simulated, which testify to the presence of the Moon moving away from the Earth and the influence of the effects of movement on its course. The significant dependence of the final result on numerical methods of integration, computer calculation tools, and the values of space-velocity initial conditions is shown. The results of the simulation of transient processes are attached.

Towards quantum telescopes: demonstration of a two-photon interferometer for precision astrometry.

Classical optical interferometry requires maintaining live, phase-stable links between telescope stations. This requirement greatly adds to the cost of extending to long baseline separations and limits on baselines will in turn limit the achievable angular resolution. Here we describe a novel type of two-photon interferometer for astrometry, which uses photons from two separate sky sources and does not require an optical link between stations. Such techniques may make large increases in interferometric baselines practical, even by orders of magnitude, with a corresponding improvement in astrometric precision benefiting numerous fields in astrophysics. We tested a benchtop analogue version of the two-source interferometer and unambiguously observe correlated behavior in detections of photon pairs from two thermal light sources, in agreement with theoretical predictions. This work opens new possibilities in future astronomical measurements.

Constraints on cosmological model in Weyl-Cartan spacetime from astronomical measurements

In order to give some lights on the issue of Hubble tension, alternative to Riemannian spacetime, we investigate a cosmological model in Weyl-Cartan spacetime by astronomical measurements, where a new density parameter Ω ϕ is introduced to denote the non-Riemannian spacetime structure, which scales as ∼(1 + z)6. Based on Markov Chain Monte Carlo estimation and taking astronomical measurements of cosmic microwave background (Planck 2018), baryon acoustic oscillations and Type Ia supernova (Pantheon), model parameters of our considering case are constrained. Our results show that Hubble tension cannot be alleviated in Weyl-Cartan cosmology. However, constraints on the parameter Ω ϕ can not be distinguished from ΛCDM model in 1σ confidence region. Moreover, the space of the Universe is infinite and unbounded, and an upper limit of the model parameter Ω ϕ is also obtained. Additionally, it is worth noting that results obtained in this work are valid for models that the scaling behavior of density parameters is same to our considering case.

Constraints on primordial black holes in the mixed dark matter scenarios using the ratio (3He+D)/H\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathrm (^3{He}+D)/H$$\\end{document}

We derive the upper limit on the dark matter (DM) fraction in primordial black holes (PBHs) in the mixed DM scenarios. In this scenarios, a PBH can accrete weakly interacting massive particles (WIMPs) to form a ultracompact minihalo (UCMH) with a density profile of ρDM(r)∼r-9/4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\rho _{\ extrm{DM}}(r)\\sim r^{-9/4}$$\\end{document}. The energy released from UCMHs due to dark matter annihilation has influence on the photodissociation of 4He\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{4}{\ extrm{He}}$$\\end{document}, producing the 3He\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$^{3}{\ extrm{He}}$$\\end{document} and the D. By requiring that the ratio (3He+D)/H\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(^3\ ext {He}+\ ext {D})/\ ext {H}$$\\end{document} caused by UCMHs does not exceed the measured value, we derive the upper limit on the dark matter fraction in PBHs. For the canonical value of DM thermally averaged annihilation cross section σv=3×10-26cm3s-1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\left<\\sigma v\\right>=3\ imes 10^{-26}\ ext {cm}^{3}\\,\ ext {s}^{-1}$$\\end{document}, we find that the upper limit is fPBH<0.35(0.75)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f_{\ extrm{PBH}} < 0.35(0.75)$$\\end{document} for DM mass mχ=1(10)GeV\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$m_{\\chi }=1(10)~ \ ext {GeV}$$\\end{document}. Compared with other limits obtained by different astronomical measurements, although our limit is not the strongest, we provide a different way of constraining the cosmological abundance of PBHs.

Bianchi type-III bulk-viscous string models in scalar–tensor theory of gravitation

In this paper, we have investigated Bianchi type-III bulk-viscous string cosmological models in the frame-work of scalar–tensor theory of gravitation. To solve the field equations for the bulk-viscous fluid and perfect fluid under the following physically relevant conditions: (i) Expansion scalar ([Formula: see text]) in the model is directly proportional to the shear scalar ([Formula: see text]). (ii) [Formula: see text], where [Formula: see text] is a constant (iii) [Formula: see text], where [Formula: see text] and [Formula: see text] are real constants. The observed phase transition of the presented universe from the early decelerating phase to the present epoch is in good accordance with the astronomical measurements. A detailed discussion on energy conditions and stability of the all models is analyzed through graphical representation.

Astronomical measurements 1923–2023: a century of astonishing progress

How have advances in technology changed astronomy over the past 100 years? In this very brief review I will give examples of just how closely discovery has followed technical innovation, allowing observations that would previously have seemed impossible. Obviously great progress has come from spaceflight allowing observations from outside the Earth’s atmosphere. But two other factors have also been crucial—the development of efficient detectors of electromagnetic radiation and the application of computers to both instrument control and data analysis. Driving down experimental errors in pursuit of ever-more accurate measurements has been important too. I will particularly highlight advances in cosmology, the nature of galactic nuclei and the discovery of exoplanets.

Influence of the deviation of the matter power spectrum at small scales on the global 21-cm signal at cosmic dawn

The matter power spectrum has been strongly constrained by astronomical measurements at large scales, but only weakly at small scales. Compared with the standard scenario, the deviation of the matter power spectrum at small scales has influence on the cosmological structure formation, e.g., the comoving number density of dark matter halos. The thermal history of the intergalactic medium (IGM) can be changed if dark matter is made of weakly interacting massive particles and can annihilate into standard model particles. The changes of the evolution of IGM could leave imprints on the relevant astronomical observations. Taking into account the dark matter annihilation, we investigate the impact of the deviation of matter power spectrum at small scales on the global 21-cm signal. In view of the measurements of the global 21-cm signal by the EDGES experiment, we explore the allowed parameter space of ${m}_{s}$, which describes the degree of deviation, by requiring the differential brightness temperature of the global 21-cm signal $\ensuremath{\delta}{T}_{21}\ensuremath{\le}\ensuremath{-}50\text{ }\text{ }\mathrm{mK}$ at redshift $z=17$.

Astronomical Seeing and Meteorological Parameters at Maidanak Observatory

In this article, we present the results of astronomical seeing measurements conducted at the Maidanak observatory and the influence of meteorological parameters on astronomical seeing. A differential image motion monitor (DIMM) was used to measure astronomical seeing. Astronomical seeing observations were made between 2018–2022, mainly in the summer and autumn months. A total of 266 night observations were conducted between 2018 and 2022. For the whole time frame, the median seeing value was 0.69 arc seconds. With a median value of 0.65″, 2019 is the year with the best seeing, and 2021 has the worst seeing (0.71″). Analysis of long-term variations of the amount of clear time revealed a small trend of decrease in the amount. The correlation between the meteorological parameters and seeing was analyzed. It was determined that the meteorological parameters with the greatest impact on the seeing are wind speed and nighttime temperature variation. The correlation coefficient was equal to 13% and 21% for both quantities. It was found that wind direction and temperature have a relatively weak correlation with astronomical seeing.

Multi-Color Temperature and Magnitude Simulation for Astronomical Spectral Velocity Measurement

Multi-Color Temperature and Magnitude Simulation for Astronomical Spectral Velocity Measurement

Astronomical seeing at Maidanak Observatory with differential image motion monitor

The article presents statistics of the astronomical seeing at the Maidanak Observatory in Uzbekistan. Astronomical seeing measurements were performed using a differential image motion monitor. In the period 2018 to 2021, a total number of 204 night observations were carried out. The median zenith seeing for the entire period of observations was found to be 0.69″ (arcseconds). The results were compared with those obtained in the previous measurement period of 1996 to 2003. The comparison shows very small differences between the two measurement sets in the monthly and yearly median values. The best seeing was observed in October, but it was November according to the previous measurements. The best year in terms of seeing was 2019 with its median value 0.65″ and the worst seeing observed in 2021 (0.71″).

Digitization of 20 years of decametric observations of the Sun and Jupiter in Nançay between 1970 and 1990

Since 1970, decametric observations of the Sun and Jupiter have been acquired on a daily basis from the radio observatory of Nançay, France. The resulting database now forms the worldwide largest set of low frequency observations of the Solar Corona between 10 and 100 MHz and of the Jovian magnetosphere between 10 and 40 MHz. The Nançay Decameter Interferometer (NDI), a two-antenna interferometer, acquired pioneer observations from 1970 to 1978, using analog radio receivers tested on the Arecibo giant radiotelescope. The large Nançay Decameter array (NDA), a phased array of 144 helical antennas, was then constructed in the late 1970s as a ground-based support to the Voyager mission and started routine observations in January 1978 in replacement of the NDI, using similar spectrometers. The NDA is still in operation today and its observations, recorded in a digital format since 1990, are public and daily made accessible to the heliospheric and magnetospheric communities at https://www.obs-nancay.fr/reseau-decametrique/. Before 1990, though, the Nançay decametric observations were recorded on analog devices, such as 35-mm films, magnetic tapes and other paper supports, physically archived at the Observatory of Paris, on its site of the Observatory of Meudon, where they could only be accessed on demand. The NDA team recently undertook a multi-year effort to inventory all the Nançay decametric archives, to refurbish and digitize them in order to preserve and promote this historical data collection, most notably by extending the current public database over the 1970–1990 time interval. We digitized the full collection of 35-mm films, corresponding to a total film length of ∼45.5 km, with a specific high resolution scanner. Each roll was scanned by a series of pixel-to-pixel contiguous images recorded in TIF format with adequate metadata and naming convention. The final ∼40 Tb data volume was archived at Paris Astronomical Data Centre and the physical films were refurbished to be archived in a perennial way. We also digitized the associated observations sheets. Finally, we took advantage of this project to also digitize a sample of 35-mm films extracted from four other historical solar data collections hosted at the Observatory of Paris and dealing with two distinct Nançay radiotelescopes and two Lyot heliographs located at the Observatories of Meudon and Haute-Provence. The digitized, documented, Nançay decametric archives have been publicly released to the community in 2020 at http://archives-decametriques.obspm.fr. After having described the instruments, the data collections and the digitization pipeline, this articles ends with a few scientific case studies, focussing on the search for Jupiter-satellite decametric emissions. For instance, the digitized NDA archives suggest the presence of Gan-A and B emissions, while these were first reported in 2018. This work is a concrete example of how historical astronomical measurements can be preserved and archived along the IAU recommendation, to the benefit of the astronomical community.

NEWLY DISCOVERED ILLUSTRATED TEXTS OF ARATUS AND ERATOSTHENES WITHIN CODEX CLIMACI RESCRIPTUS

AbstractThis article presents texts recovered by post-processing of multispectral images from the fifth- or sixth-century underwriting of the palimpsest Codex Climaci Rescriptus. Texts identified include the Anonymous II Proemium to Aratus’ Phaenomena, parts of Eratosthenes’ Catasterisms, Aratus’ Phaenomena lines 71–4 and 282–99 and previously unknown text, including some of the earliest astronomical measurements to survive in any Greek manuscript. Codex Climaci Rescriptus also contains at least three astronomical drawings. These appear to form part of an illustrated manuscript, with considerable textual value not merely on the basis of its age but also of its readings. The manuscript undertexts show significant overlap with the Φ Edition, postulated as ancestor of the various Latin Aratea.

Embedded Foucault’s Pendulum Amplitude Measurement and Control System

This article deals with the problem of measuring the amplitude of the Foucault’s pendulum. In this context, the applied methods and procedures are first described, after which the structure of the embedded system for measuring and controlling the amplitude of the Foucault’s pendulum is presented. It is mentioned that in order to provide planetary astronomical measurements, the architecture of the measurement and control system must fit into the edge-to-cloud continuous computing paradigm. For this purpose, the pendulum must be kept in oscillation mode, without interfering with natural phenomena affecting the pendulum.

Probing physics beyond the standard model: limits from BBN and the CMB independently and combined

We present new Big Bang Nucleosynthesis (BBN) limits on the cosmic expansion rate or relativistic energy density, quantified via the number Nν of equivalent neutrino species. We use the latest light element observations, neutron mean lifetime, and update our evaluation for the nuclear rates d + d ⟶ 3He + n and d + d ⟶ 3H+ p. Combining this result with the independent constraints from the cosmic microwave background (CMB) yields tight limits on new physics that perturbs Nν and η prior to cosmic nucleosynthesis: a joint BBN+CMB analysis gives Nν = 2.898 ± 0.141, resulting in Nν < 3.180 at 2σ. We apply these limits to a wide variety of new physics scenarios including right-handed neutrinos, dark radiation, and a stochastic gravitational wave background. The strength of the independent BBN and CMB constraints now opens a new window: we can search for limits on potential changes in Nν and/or the baryon-to-photon ratio η between the two epochs. The present data place strong constraints on the allowed changes in Nν between BBN and CMB decoupling; for example, we find -0.708 < Nν CMB - Nν BBN < 0.328 in the case where η and the primordial helium mass fraction Yp are unchanged between the two epochs; we also give limits on the allowed variations in η or in (η, Nν ) jointly. We discuss scenarios in which such changes could occur, and show that BBN+CMB results combine to place important constraints on some early dark energy models to explain the H0 tension. Looking to the future, we forecast the tightened precision for Nν arising from both CMB Stage 4 measurements as well as improvements in astronomical 4He measurements. We find that CMB-S4 combined with present BBN and light element observation precision can give σ(Nν ) ≃ 0.03. Such future precision would reveal the expected effect of neutrino heating (Neff -3 = 0.044) of the CMB during BBN, and would be near the level to reveal any particle species ever in thermal equilibrium with the standard model. Improved Yp measurements can push this precision even further.

Learning to detect radio frequency interference in radio astronomy without seeing it

ABSTRACT Radio frequency interference (RFI) corrupts astronomical measurements, thus affecting the performance of radio telescopes. To address this problem, supervised-segmentation models have been proposed as candidate solutions to RFI detection. However, the unavailability of large labelled data sets, due to the prohibitive cost of annotating, makes these solutions unusable. To solve these shortcomings, we focus on the inverse problem: training models on only uncontaminated emissions, thereby learning to discriminate RFI from all known astronomical signals and system noise. We use nearest latent neighbours – an algorithm that utilizes both the reconstructions and latent distances to the nearest neighbours in the latent space of generative autoencoding models for novelty detection. The uncontaminated regions are selected using weak labels in the form of RFI flags (generated by classical RFI flagging methods) available from most radio astronomical data archives at no additional cost. We evaluate performance on two independent data sets, one simulated from the Hydrogen Epoch of Reionization Array (HERA) telescope and the other consisting of real observations from the Low-Frequency Array (LOFAR) telescope. Additionally, we provide a small expert-labelled LOFAR data set (i.e. strong labels) for evaluation of our and other methods. Performance is measured using the area under the receiver operating characteristic (AUROC), area under precision–recall curve (AUPRC), and the maximum F1-score for a fixed threshold. For the simulated HERA data set, we outperform the current state of the art across all metrics. For the LOFAR data set, our algorithm offers both a 4 per cent increase in AUROC and AUPRC at the cost of increasing the false negative rate, but without any manual labelling.