Ground-based Telescopes Research Articles

Image Quality Specification for Solar Telescopes

Modern large ground-based solar telescopes are invariably equipped with adaptive optics systems to enhance the high angular resolution imaging and spectroscopic capabilities in the presence of the Earth's atmospheric turbulence. The quality of the images obtained from these telescopes can not be quantified with the Strehl ratio or other metrics that are used for nighttime astronomical telescopes directly. In this paper, we propose to use the root mean square (rms) granulation contrast as a metric to quantify the image quality of ground-based solar telescopes. We obtain semi-logarithmic plots indicating the correspondence between the Strehl ratio and the rms granulation contrast for most practical values of the telescope diameters (D) and the atmospheric coherence diameters ($ r_0$), for various levels of adaptive optics compensation. We estimate the efficiency of a few working solar adaptive optics systems by comparing the results of our simulations with the Strehl ratio and rms granulation contrast published by these systems. Our results can be used in conjunction with a plausible 50 system efficiency to predict the lower bound on the rms granulation contrast expected from ground-based solar telescopes.

用于地月空间VLBI的加权全频谱信号合成技术

<p indent="0mm">In the Chang’E-7 mission of the fourth stage of China’s Lunar Exploration Project, the relay satellite will carry a 4.1-m-aperture X-band parabolic telescope. This and the ground-based telescopes will form a lunar orbit very long baseline interferometry (VLBI) experimental system with the space-ground baseline up to 400000 km. To improve the sensitivity of this baseline, we propose a weighted full-spectrum signal combining method. First, we derive the optimal weighting coefficient ratio for combining the signals of the two telescopes. Then, we propose the VLBI weighted full-spectrum combining method whose optimal weight coefficient is determined by investigating the data, and the obtained result is consistent with the theoretical derivation. Finally, we use Chang’E-4 original VLBI observation data for method testing. The results show that the signal combining method proposed in this work can greatly improve the signal-to-noise ratio for VLBI observations.

Statistical Analysis on the Number of Discoveries and Discovery Scenarios of Near-Earth Asteroids

Near-Earth asteroids (NEAs) are a kind of small solar system bodies that may lead to potential hazard to the safety of the Earth. Currently, most of the NEAs are discovered with ground-based telescopes and the number is still growing. In order to provide references and experience to our future near-Earth asteroid discovery and monitoring, we perform a multi-dimensionally statistical analysis on the discovery data of NEAs with public database obtained from the website of Minor Planet Center (MPC). We find the constraint of observation ability can lead to selection effect on the discoveries, which causes a yearly dependence trend and a size-dependence characteristic of the relative proportion for different orbit types of discovered NEAs. Besides, combined with the orbits obtained from numerical simulations, we revisit the discovery scenarios of these objects. The position distribution of the objects under different celestial coordinate systems are obtained, and the dependence on seasons, observatory latitudes, and the diameters are analyzed. Finally, we quantify the impact of the Sun, the Moon, and the galactic plane on the discoveries by analyzing the observation data, and find that ground-based telescopes generally have difficulty in discovering NEAs within 90∘ from the Sun direction, and that this limitation generally has a greater impact on smaller-sized objects. The lunar position also has a significant effect on the discoveries, with the restriction on the nights before and after the full Moon resulting in 29% of NEAs being undiscovered, and analysis shows that objects found in the first half of the lunar calendar month are generally more difficult to be followed than those found in the second half. The galactic plane, especially the direction near the galactic center, also has an effect on the discoveries, resulting in a season-dependent “blind spot” for observations near the ecliptic.

Application of Neural Networks to Estimation and Prediction of Seeing at the Large Solar Telescope Site

Optical turbulence limits the angular resolution of ground-based astronomical telescopes. The key parameter of optical turbulence is seeing. In this study, seasonal variations of seeing estimated from differential image motion monitor measurements at the Large Solar Telescope site are discussed. The Large Solar Telescope will be located at an elevation of 2000 m above sea level ( N, ). The highest seeing values are observed in winter. The median of seeing is 2.″1. In summer, the median decreases to 1.″1. The best atmospheric conditions are observed in April–May, when the medians of seeing are low and the standard deviations are high. During this period, atmospheric situations with low values of seeing (∼0.″5–0.″6) are often observed. We simulated multilayer neural networks for the measured seeing by applying a group method of data handling. Modeled seeing is well described in terms of mean meteorological parameters, which include wind speed components and large-scale vorticity of air flows at different altitudes in the atmosphere. The 12-layer optimal neural network obtained has a high correlation coefficient between modeled and measured seeing values. The linear correlation coefficient is 0.77.

Artificial neural networks for galaxy clustering: Learning from the two-point correlation function of BOSS galaxies

The increasingly large amount of cosmological data coming from ground-based and space-borne telescopes requires highly efficient and fast enough data analysis techniques to maximise the scientific exploitation. In this work, we explore the capabilities of supervised machine learning algorithms to learn the properties of the large-scale structure of the Universe, aiming at constraining the matter density parameter, Ωm. We implement a new Artificial Neural Network for a regression data analysis, and train it on a large set of galaxy two-point correlation functions in standard cosmologies with different values of Ωm. The training set is constructed from log-normal mock catalogues which reproduce the clustering of the Baryon Oscillation Spectroscopic Survey (BOSS) galaxies. The presented statistical method requires no specific analytical model to construct the likelihood function, and runs with negligible computational cost, after training. We test this new Artificial Neural Network on real BOSS data, finding Ωm=0.309±0.008, which is consistent with standard analysis results.

TeV emission from Gamma Ray Bursts, checking the hadronic model

Gamma-Ray Bursts (GRBs) are the most luminous explosions in the Universe. Their luminous prompt emission makes them detectable from cosmological distances. Most GRBs have been detected below a few MeV, however at least a hundred GRBs have been detected at high (0.1 GeV) energies and observed up to tens of GeV with the Fermi Large Area Telescope (LAT). Some GRBs have been observed at (0.1–1) TeV by ground-based imaging atmospheric Cherenkov telescopes. To date, the high energy emission mechanism is not understood. In this paper we review the possible leptonic and hadronic mechanisms capable of producing the ∼ TeV emission detected in GRBs. In paricular we concentrate on the hadronic origin of this radiation component and discuss in detail the numerical simulation elaborated to reproduce the observed sub-TeV observations of GRB190114C.

НАЗЕМНА ПІДТРИМКА КОСМІЧНОЇ МІСІЇ PARKER УКРАЇНСЬКИМИ НИЗЬКОЧАСТОТНИМИ РАДІОТЕЛЕСКОПАМИ

Subject and Purpose. The sporadic radio emissions coming from the Sun in a broad frequency range contain a lot of important information concerning the solar corona, parameters of the radio frequency sources therein, and the parameter variations resulting from active processes on and about the Sun. These have been the reasons for recent launches of the space missions intended for stud- ying the Sun and its corona, such as the Parker Solar Probe (PSP) and the Solar Orbiter. The present work is aimed at demonstrating effectiveness of the ground-based support for the space missions, the PSP before all, which is provided by the large Ukrainian radio telescopes of the decameter wavelength range. Another purpose has been cross-calibration of the space-borne radiometer against calibrated data from a ground-based instrument. Methods and Methodology. One of the remote diagnosis techniques widely used with respect to the solar corona is to analyze parameters of the radio frequency emissions from sources lying at a variety of altitudes within the corona. The methodology of such joint, space-borne/terrestrial investigations suggests simultaneous observations of certain individual events during closest approach of the space probe PSP to the Sun, with analysis over a widest possible frequency range. The data obtainable within overlapping fre- quency bands are proposed for calibrating the on-board radio receivers of the space probe. Results. The methodology proposed for joint, space-based / terrestrial observations has been substantiated. Data from the UTR-2 and URAN-2 radio telescopes and the space probe PSP have been used to plot the dynamic and the polarization spectra of the June 9, 2020 solar bursts, with identification and comparison of the relevant individual events. A joint dynamic spectrum of these bursts has been obtained for the frequency band of 0.5 to 32 MHz. The calibrated data from the ground-based radio telescopes have allowed performing cross-calibration of the HF receiver in the FIELDS-PSP data taking module within the frequency band of 10 to 18 MHz. Conclusions. The paper has provided evidence of an effective ground-based support for the space mission PSP on the part of large Ukrainian radio telescopes. Examples of joint observations have been given, and a methodology described which is employed for cross-calibrating the HF receivers of the FIELD-PSP module. Prospects are outlined of further ground-based support for solar space research missions.

Method of increasing the accuracy of the star sensor

A new algorithm for filtering distortions of the deep image of the starry sky is considered to improve the accuracy of determining the position of the star - the detection of the centroid. An increase in the accuracy of measuring the orientation parameters of the spacecraft by stellar sensors is being investigated. The method of calculations using the algorithm of exact estimation of the centroid is applied, restoring the function of the scatter of points from recorded astronomical images. Minimization of the effects of atmospheric turbulence and system noise on long-exposure images obtained by a ground-based telescope is proposed. The method was tested in the MATLAB environment for a real image of the deep sky recorded by the ground system.

Synchrotron self-compton emission in the two-component jet model for gamma-ray bursts

Gamma-ray bursts (GRBs) are intense bursts of high-energy photons (prompt emissions) caused by relativistic jets. After the emissions, multi-wavelength afterglows, from radio to very-high-energy (VHE) gamma-ray, last for more than a few days. In the past three years, the VHE gamma-ray photons from four GRBs (GRBs 180720B, 190114C, 190829A and 201216C) were detected by ground-based Imaging Atmospheric Cherenkov Telescopes, such as the Major Atmospheric Gamma Imaging Cherenkov (MAGIC) telescopes and the High Energy Stereoscopic System (H.E.S.S.). One of them, GRB 190829A, had some peculiar features of showing achromatic peaks in X-ray and optical bands at 1.4×103 s and being classified as low-luminosity GRBs. Previously, we proposed a two-component jet model, which has ‘narrow jet’ with a small initial opening half-angle θ0=0.015 rad and large bulk Lorentz factor Γ0=350, and ‘wide jet’ with θ0=0.1 rad and Γ0=20. The narrow jet explained the early X-ray and optical emissions and apparently small isotropic gamma-ray energy and peak energy in the off-axis viewing case. Furthermore, the late X-ray and radio (1.3 and 15.5 GHz) afterglows were emitted from the wide jet. Here, we calculate the VHE gamma-ray flux by the synchrotron self-Compton (SSC) emission. The multi-wavelength afterglows of GRB 190829A including the VHE gamma-ray emission are well explained by our two-component jet model. The afterglow emissions from our two-component jet are also consistent with the observational results of GRBs 180720B, 190114C and 201216C, when the jets are viewed on-axis. Furthermore, we discuss the detectability of off-axis orphan afterglows by the Cherenkov Telescope Array (CTA).

The PhotoDissociation Region Toolbox: Software and Models for Astrophysical Analysis

The PhotoDissociation Region Toolbox provides comprehensive, easy-to-use, public software tools and models that enable an understanding of the interaction of the light of young, luminous, massive stars with the gas and dust in the Milky Way and in other galaxies. It consists of an open-source Python toolkit and photodissociation region (PDR) models for analysis of infrared and millimeter/submillimeter line and continuum observations obtained by ground-based and suborbital telescopes, and astrophysics space missions. PDRs include all of the neutral gas in the interstellar medium where far-ultraviolet photons dominate the chemistry and/or heating. In regions of massive star formation, PDRs are created at the boundaries between the H ii regions and neutral molecular cloud, as photons with energies 6 eV < h ν < 13.6 eV photodissociate molecules and photoionize metals. The gas is heated by photoelectrons from small grains and large molecules and cools mostly through far-infrared (FIR) fine-structure lines like [O i] and [C ii]. The models are created from state-of-the art PDR codes that include molecular freeze-out; recent collision, chemical, and photorates; new chemical pathways, such as oxygen chemistry; and allow for both clumpy and uniform media. The models predict the emergent intensities of many spectral lines and FIR continuum. The tools find the best-fit models to the observations and provide insight into the physical conditions and chemical makeup of the gas and dust. The PDR Toolbox enables novel analysis of data from telescopes such as the Infrared Space Observatory, Spitzer, Herschel, the Stratospheric Terahertz Observatory, the Stratospheric Observatory for Infrared Astronomy, the Submillimeter Wave Astronomy Satellite, the Atacama Pathfinder Experiment, the Atacama Large Millimeter/submillimeter Array, and the JWST.

Ultra-fast infrared detector for astronomy

The advent of multi-messenger astronomy requires time-domain telescope detectors across the whole electromagnetic spectrum. Furthermore, astronomical fast transients such as FRBs (Fast Radio Bursts) and GRBs (Gamma Ray Bursts) lead to the concept of time-domain astronomy. FAIRTEL, an ultrafast infrared detector for ground-based telescopes, is under development thanks to funding from the Istituto Nazionale di Fisica Nucleare (INFN).

Super diffraction limit spectral imaging detection and material type identification of distant space objects.

The image information of distant objects shows a diffuse speckle pattern due to diffraction limit, non-uniform scattering, etc., which is difficult to achieve object discrimination. In this study, we have developed a staring spectral video imaging system mounted on a ground-based telescope observation platform to detect the high orbit space objects and gain their spectral images for six groups of GEO targets. The speckle remains basically the same characteristic as the projection structure of the object due to "the balloon inflation phenomenon of near parallel light during long-distance atmospheric transmission" under the premise of considering the bi-directional reflection distribution function (BRDF), Rayleigh scattering theory, and the memory effect. Based on this phenomenon, a mathematical model of remote target scattering spectrum imaging is established where the speckle can be treated as both a global speckle and speckle combination of texture blocks caused by various components of the target. The radial basis function (RBF) neural network is separately used to invert the global speckle and the speckle combination of the texture blocks on account of the typical target material database. The results show that the target materials are of relatively fewer kinds in the global inversion with only including gallium arsenide panel (GaAs) and carbon fiber (CF), for which the highest goodness of curve fitting is only 77.97. An improved algorithm makes their goodness of fit reach 90.29 and 93.33, respectively, in view of one conjecture that the target surface contains unknown materials. The spectral inversion result of the texture blocks shows that the types of materials in each target texture block increase significantly, and that the area ratio of different materials inverted in the block is different from each other. It is further confirmed that the speckle image contains the overall projection structure of distant target and the spectral image projection of each component is relatively fixed, which is the result of the comprehensive action of various mechanisms of ultra-long-haul atmospheric transmission and optical system focusing imaging after BRDF spectral scattering. The spectral image fine inversion is expected to restore the clear structure of the target. This discovery provides important support for the remote imaging and identification of distant and ultra-diffractive targets.

Precipitable Water Vapor and Fractional Clear Sky Statistics within the Big Telescope Alt-Azimuthal Region

The development of a network of ground-based telescopes requires detailed astroclimatic studies. This paper presents the spatial distributions of precipitable water vapor (PWV), total cloud cover (TCC) and cloud base height (CBH). With the aim of a representative description of the precipitable water vapor, a method for correcting this characteristic which takes into account the underlying surface is proposed. The method uses the exponential decrease in the water vapor content with the altitude and is based on the calculation of the averaged elevation of the grid nodes around the site. By applying this correction method, the seasonal changes in the median PWV values at the sites of Ali, Muztag-Ata and Suffa, as well as within the Chajnantor area are estimated. We show that the decrease of PWV with the altitude is exponential with a height scale of 1000 m for the sites in South America and Eurasia. The astroclimatic characteristics within the Big Telescope Alt-azimuthal (BTA) region (40∘N–50∘N; 35∘E–55∘E) are estimated. In this region, the sites suitable for the millimeter and submillimeter (mm/submm) observations are revealed. New sites are Mt. Horai and Mt. Kurapdag. In addition, we show that the Era-5 reanalysis data overestimate the PWV values by 1–2 mm and describe changes in the monthly medians of PWV. Comparison of the calculated medians with the measured PWV show that the correlation coefficient between these characteristics is 0.97.

First Study of Optical Turbulence Over an Astronomical Site in the Central Himalayas Using ST Radar Observations

Optical turbulence in the atmosphere is a key factor which governs the sharpness of images produced from ground-based optical telescopes. The intensity of optical turbulence can be conveniently assessed by the estimation of the refractive index structure constant ([Formula: see text]). Here, observations from a stratosphere troposphere radar (206.5[Formula: see text]MHz) that is co-located with the optical telescope facilities in the central Himalayas, are used for the estimation of [Formula: see text]. The integrated profile of [Formula: see text] and winds over about 2–20[Formula: see text]km have been used to estimate seasonal and diurnal variation of “seeing”, wavefront coherence time, isoplanatic angle and scintillation rate. The mean [Formula: see text] over the site varies from 10[Formula: see text] to 10[Formula: see text][Formula: see text]m[Formula: see text] with the largest values in the monsoon and post-monsoon season. The best “seeing” conditions are observed in the winter and post-monsoon season with median “seeing” varying from 0.39[Formula: see text] to 0.81[Formula: see text]. The largest contribution to the diurnal variation of “seeing” comes from turbulences at 2–5[Formula: see text]km height region. A weak correlation of diurnal variation of “seeing” has been observed with surface temperature and relative humidity (RH). Among astroclimatic parameters, the largest isoplanatic angle is associated with winter season with median value of 2.57[Formula: see text] and wavefront coherence time of ∼4.2[Formula: see text]ms. The least scintillation in intensity is observed in the winter season with a rate of ∼10% and most in monsoon season with ∼45% rate. This study is expected to have a positive impact on the optimization of the operation of adaptive optical techniques, observing time and scheduling of scientific programmes for optical telescope facilities in this region of the central Himalayas.

Multi-frame blind deconvolution and phase diversity with statistical inclusion of uncorrected high-order modes

Context. Images collected with ground-based telescopes suffer blurring and distortions from turbulence in the Earth’s atmosphere. Adaptive optics (AO) can only partially compensate for these effects. Neither multi-frame blind deconvolution (MFBD) methods nor speckle techniques perfectly restore AO-compensated images to the correct power spectrum and contrast. MFBD methods can only estimate and compensate for a finite number of low-order aberrations, leaving a tail of uncorrected high-order modes. Restoration of AO-corrected data with speckle interferometry depends on calibrations of the AO corrections together with assumptions regarding the height distribution of atmospheric turbulence. Aims. We seek to develop an improvement to MFBD image restoration that combines the use of turbulence statistics to account for high-order modes in speckle interferometry with the ability of MFBD methods to sense low-order modes that can be partially corrected by AO and/or include fixed or slowly changing instrumental aberrations. Methods. We modify the MFBD image-formation model by supplementing the fitted low-order wavefront aberrations with tails of random high-order aberrations. These tails follow Kolmogorov statistics scaled to estimated or measured values of Fried’s parameter, r0, that characterize the strength of the seeing at the moment of data collection. We refer to this as statistical diversity (SD). We test the implementation of MFBD with SD with noise-free synthetic data, simulating many different values of r0 and numbers of modes corrected with AO. Results. Statistical diversity improves the contrasts and power spectra of restored images, both in accuracy and in consistency with varying r0, without penalty in processing time. Together with focus diversity (FD, or traditional phase diversity), the results are almost perfect. SD also reduces errors in the fitted wavefront parameters. MFBD with SD and FD seems to be resistant to errors of several percentage in the assumed r0 values. Conclusions. The addition of SD to MFBD methods shows great promise for improving contrasts and power spectra in restored images. Further studies with real data are merited.

A Variable Parameter Linear Tracking Differentiator and Its Application in Large Ground-based Telescopes

This paper is concerned with the characteristics of a tracking differentiator (TD) in arranging transition process for the physical system. In order to overcome disadvantages of linear TD (LTD) in practice, a novel variable parameter linear tracking differentiator (VLTD) is proposed. By designing the speediness factor as a function of the tracking error, the VLTD can track a large range of set values with reasonable speed and acceleration. Analysis shows that VLTD can converge to its set value under certain conditions. Meanwhile, the speed and acceleration bounds are added to the VLTD, which guarantees that the proposed transition signal really plays a transitional role. The numerical simulation results emphasize necessity for adding speed and acceleration bounds to the VLTD. By comparing VLTD with the nonlinear TD (NLTD) in the simulations and experiments, VLTD can achieve almost the same performance as the NLTD while it is easier to be implemented.

Correction performance uniformity on ground-layer adaptive optics

ABSTRACTGround-layer adaptive optics (GLAO) is generally used to improve the seeing for large-aperture ground-based optical telescopes across a wide field of view with uniform imaging quality. In this paper, a new criterion, which is defined as the weighted sum of the mean and mean-square-error values of the full width at half-maximum of the field-dependent point spread function of the image over the whole field of view, is proposed to evaluate GLAO performance uniformity. An analytic model of the GLAO-corrected point spread function based on spatial filtering methods is used to investigate the uniformity and image quality over the whole field of view for different guide-star layouts, telescope apertures, numbers of actuators for the deformable mirror, and turbulence profiles. Simulations are performed on the GLAO configurations for the 1-m New Vacuum Solar Telescope at Fuxian Solar Observatory. The results show that, compared with that of the classical evaluation, the correction uniformity improves by 63 per cent, with the resolution sacrificing only 5 per cent for a measured turbulence profile at Fuxian Solar Observatory. Furthermore, this criterion is applied to various requirements, and some critical system parameters are suggested for the wide field-of-view GLAO.

Rome Precision Solar Photometric Telescope: precision solar full-disk photometry during solar cycles 23–25

The Rome Precision Solar Photometric Telescope (Rome/PSPT) is a ground-based telescope engaged in precision solar photometry. It has a 27-year database of full-disk images of the photosphere and chromosphere beginning in 1996 and continuing to 2022. The solar images have been obtained daily, weather permitting, with approximately 2 arcsec/pixel scale in Ca II K line at 393.3 nm, G-band at 430.6 nm, and continuum in the blue and red parts of the spectrum at 409.4 nm and 607.2 nm, respectively. Regular observations were also performed at the green continuum at 535.7 nm for a period of about 18 months. Since the first-light, Rome/PSPT operations have been directed at understanding the source of short-and long-term solar irradiance changes, spanning from 1 min to several months, and from 1 year to a few solar cycles, respectively. However, Rome/PSPT data have also served to study a variety of other topics, including the photometric properties of solar disk features and of the supergranulation manifested by the chromospheric network. Moreover, they have been unique in allowing to connect series of historical and modern full-disk solar observations, especially the Ca II K line data. Here, we provide an overview of the Rome/PSPT telescope and of the solar monitoring carried out with it from its first light to the present, across solar cycles 23–25. We also briefly describe the main results achieved with Rome/PSPT data, and give an overview of new results being derived with the whole time series of observations covering the period 1996–2022.

Hot Exoplanet Atmospheres Resolved with Transit Spectroscopy (HEARTS)

Context. High-resolution transmission spectroscopy has allowed for in-depth information on the composition and structure of exoplanetary atmospheres to be garnered in the last few years, especially in the visible and in the near-infrared. Many atomic and molecular species have been detected thanks to data gathered from state-of-the-art spectrographs installed on large ground-based telescopes. Nevertheless, the Earth daily cycle has been limiting observations to exoplanets with the shortest transits. Aims. The inflated sub-Saturn KELT-11 b has a hot atmosphere and orbits a bright evolved subgiant star, making it a prime choice for atmospheric characterization. The challenge lies in its transit duration – of more than 7 h – which can only be covered partially or without enough out-of-transit baselines when observed from the ground. Methods. To overcome this constraint, we observed KELT-11 b with the HARPS spectrograph in series of three consecutive nights, each focusing on a different phase of the planetary orbit: before, during, and after the transit. This allowed us to gather plenty of out-of-transit baseline spectra, which was critical to build a spectrum of the unocculted star with sufficient precision. Telluric absorption lines were corrected using the atmospheric transmission code MOLECFIT. Individual high-resolution transmission spectra were merged to obtain a high signal-to-noise transmission spectrum to search for sodium in KELT-11 b’s atmosphere through the ~5900 Å doublet. Results. Our results highlight the potential for independent observations of a long-transiting planet over consecutive nights. Our study reveals a sodium excess absorption of 0.28 ± 0.05% and 0.50 ± 0.06% in the Na D1 and D2 lines, respectively. This corresponds to 1.44 and 1.69 times the white-light planet radius in the line cores. Wind pattern modeling tends to prefer day-to-night side winds with no vertical winds, which is surprising considering the planet bloatedness. The modeling of the Rossiter-Mclaughlin effect yields a significantly misaligned orbit, with a projected spin-orbit angle of λ = −77.86−2.26+2.36∘. Conclusions. Belonging to the under-studied group of inflated sub-Saturns, the characteristics of KELT-11 b – notably its extreme scale height and long transit – make it an ideal and unique target for next-generation telescopes. Our results as well as recent findings from HST, TESS, and CHEOPS observations could make KELT-11 b a benchmark exoplanet in atmospheric characterization.

A 16 hr Transit of Kepler-167 e Observed by the Ground-based Unistellar Telescope Network

More than 5000 exoplanets have been confirmed and among them almost 4000 were discovered by the transit method. However, few transiting exoplanets have an orbital period greater than 100 days. Here we report a transit detection of Kepler-167 e, a “Jupiter analog” exoplanet orbiting a K4 star with a period of 1071 days, using the Unistellar ground-based telescope network. From 2021 November 18 to 20, citizen astronomers located in nine different countries gathered 43 observations, covering the 16 hr long transit. Using a nested sampling approach to combine and fit the observations, we detected the midtransit time to be UTC 2021 November 19 17:20:51 with a 1σ uncertainty of 9.8 minutes, making it the longest-period planet to ever have its transit detected from the ground. This is the fourth transit detection of Kepler-167 e, but the first made from the ground. This timing measurement refines the orbit and keeps the ephemeris up to date without requiring space telescopes. Observations like this demonstrate the capabilities of coordinated networks of small telescopes to identify and characterize planets with long orbital periods.