Observations with ground-based telescopes are affected by differential atmospheric dispersion due to the wavelength-dependent index of refraction of the atmosphere. The usage of an Atmospheric Dispersion Corrector (ADC) is fundamental to compensate this effect. Atmospheric dispersion correction residuals above the level of ~ 100 milli-arcseconds (mas) will affect astronomical observations, in particular radial velocity and flux losses. The design of an ADC is based on atmospheric models. To the best of our knowledge, those models have never been tested on-sky. In this paper, we present a new method to measure the atmospheric dispersion on-sky in the optical range. We require an accuracy better than 50 mas that is equal to the difference between atmospheric models. The method is based on the use of cross-dispersion spectrographs to determine the position of the centroid of the spatial profile at each wavelength of each spectral order. The method is validated using cross-dispersed spectroscopic data acquired with the slit spectrograph UVES. We measure an instrumental dispersion of 47 mas in the blue arm, 15 mas, and 23 mas in the two ranges of the red arm. We also measure a 4 % deviation in the pixel scale from the value cited in UVES manual. The accuracy of the method is ~ 17 mas in the range of 315-665 nm. At this level, we can compare and characterize different atmospheric dispersion models for better future ADC designs.
Design, implementation, and on-sky performance of an advanced apochromatic triplet atmospheric dispersion corrector for the Magellan adaptive optics system and VisAO camera
In order to evaluate the ground-based infrared telescope sensitivity affected by the noise from the atmosphere, instruments and detectors, we construct a sensitivity model that can calculate limiting magnitudes and signal-to-noise ratio ($S/N$). The model is tested with tentative measurements of $\rm M'$-band sky brightness and atmospheric extinction obtained at the Ali and Daocheng sites. We find that the noise caused by an excellent scientific detector and instruments at $-135^\circ \rm C$ can be ignored compared to the $\rm M'$-band sky background noise. Thus, when $S/N=3$ and total exposur…
Differential atmospheric dispersion is a wavelength-dependent effect introduced by Earth's atmosphere that affects astronomical observations performed using ground-based telescopes. It is important, when observing at a zenithal angle different from zero, to use an Atmospheric Dispersion Corrector (ADC) to compensate this atmospheric dispersion. The design of an ADC is based on atmospheric models that, to the best of our knowledge, were never tested against on-sky measurements. We present an extensive models analysis in the wavelength range of 315-665 nm. The method we used was previously descr…
Observations with ground-based telescopes are affected by differential atmospheric dispersion when seen at a zenith angle different from zero, a consequence of the wavelength-dependent index of refraction of the atmosphere. One of the pioneering technology in detecting exoplanets is the technique of radial velocity (RV), that can be affected by uncorrected atmospheric dispersion. The current highest precision spectrographs are expected to deliver a precision of 10 cm/s (e.g., ESPRESSO). To minimize the atmospheric dispersion effect, an Atmospheric Dispersion Corrector (ADC) can be employed. AD…
Low-frequency radio observatories are reaching unprecedented levels of sensitivity in an effort to detect the 21 cm signal from the Cosmic Dawn. High precision is needed because the expected signal is overwhelmed by foreground contamination, largely from so-called diffuse emission -- a non-localized glow comprising Galactic synchrotron emission and radio galaxies. The impact of this diffuse emission on observations may be better understood through detailed simulations, which evaluate the Radio Interferometry Measurement Equation (RIME) for a given instrument and sky model. Evaluating the RIME …
The natural night sky brightness is a relevant input for monitoring the light pollution evolution at observatory sites, by subtracting it from the overall sky brightness determined by direct measurements. It is also instrumental for assessing the expected darkness of the pristine night skies. The natural brightness of the night sky is determined by the sum of the spectral radiances coming from astrophysical sources, including zodiacal light, and the atmospheric airglow. The resulting radiance is modified by absorption and scattering before it reaches the observer. Therefore, the natural night …
The atmospheric monitoring devices for the planned calibration system of the Cherenkov Telescope Array (CTA) are undergoing intensive development, prototyping and testing. The All-Sky Cameras, the Sun/Moon Photometers and the FRAM telescopes have been gradually deployed at the future CTA sites with the primary goal of site characterization, simultaneously allowing the assessment of their operational reliability in realistic environmental conditions. All three devices have shown the ability to work smoothly in both the extreme dryness and the large temperature variations of the southern site as…
Effects of long-term atmospheric change were looked for in photometry employing the Gemini North and South twin Multi-Object Spectrograph (GMOS-N and GMOS-S) archival data. The whole GMOS imaging database, beginning from 2003, was compared against the all-sky Gaia object catalog, yielding ~10^6 Sloan r'-filter samples, ending in 2021. These were combined with reported sky and meteorological conditions, versus a simple model of the atmosphere plus cloud together with simulated throughputs. One exceptionally extincted episode in 2009 is seen, as is a trend (similar at both sites) of about 2 mmag…
AstroSkyFlow: an astronomical sky image flow simulator for time domain survey validation and machine learning
State Key Laboratory of Dark Matter Physics, Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（暗物质物理全国重点实验室，李政道研究所，上海交通大学物理与天文学院）；Shanghai Astronomical Observatory, Chinese Academy of Sciences（中国科学院上海天文台）
Modeling the optical point spread function (PSF) is particularly challenging for adaptive optics (AO)-assisted observations owing to the its complex shape and spatial variations. We aim to (i) exhaustively demonstrate the accuracy of a recent analytical model from comparison with a large sample of imaged PSFs, (ii) assess the conditions for which the model is optimal, and (iii) unleash the strength of this framework to enable the joint estimation of atmospheric parameters, AO performance and static aberrations. We gathered 4812 on-sky PSFs obtained from seven AO systems and used the same fitti…
Near-infrared thermal emissivity from ground based atmospheric dust measurements at ORM
我们提出了一个分析在Observatorio del Roque de los Muchachos（ORM;加那利群岛）测得的气溶胶的大气含量。使用位于国家伽利略望远镜（TNG）的激光二极管粒子计数器，我们探测到了0.3，0.5，1.0，3.0，5.0和10.0微米大小的粒子。计算了大气中粉尘含量的季节变化。春季比夏季多尘，但冬季也可能出现多尘情况。提出了一种在近红外波段估算气溶胶发射率对天空亮度贡献的方法。在近红外光谱中，尘埃辐射对天空背景的贡献与气辉相比可以忽略不计，在沙尘天，在Ks波段的贡献最大，约为8-10%。
Second-generation exoplanet imagers using extreme adaptive optics and coronagraphy have demonstrated their great potential for studying close circumstellar environments and for detecting new companions and helping to understand their physical properties. However, at very small angular separation, their performance in contrast is limited by several factors: diffraction by the complex telescope pupil not perfectly canceled by the coronagraph, residual dynamic wavefront errors, chromatic wavefront errors, and wavefront errors resulting from noncommon path aberrations (NCPAs). In a previous work, …
Bright Region Reset: an on-detector strategy for minimizing the impacts of atmospheric emission lines on spectral observations
University of Victoria（维多利亚大学）；NRC Herzberg Astronomy and Astrophysics Research Centre（国家研究委员会赫茨伯格天文学和天体物理学研究中心）；NSF’s NOIRlab / International Gemini Observatory（美国国家科学基金会NOIRlab / 国际双子星天文台）
maria goes NIFTy: Gaussian Process-Based Reconstruction and Denoising of Simulated (Sub-)Millimetre Single-Dish Telescope Data
Technical University of Munich（慕尼黑工业大学）；Excellence Cluster ORIGINS（ORIGINS卓越集群）；Leiden Observatory, Leiden University（莱顿大学莱顿天文台）；Yale University（耶鲁大学）；Brookhaven National Laboratory（布鲁克海文国家实验室）；European Southern Observatory（欧洲南方天文台）；Institute of Space Sciences (ICE, CSIC)（空间科学研究所（ICE，CSIC））
DD4AO control law for RISTRETTO: robustness, real-time performance, and on-sky validation with PAPYRUS
Univérsité de Genève (UNIGE)（日内瓦大学）；Wakea consulting（Wakea咨询公司）；Laboratoire d’Astrophysique de Marseille (LAM)（马赛天体物理学实验室）；Office national d’études et de recherches aérospatiales (ONERA)（法国国家航空航天研究局）
Estimating the horizontal irradiance from measurements of the zenith night sky radiance is a useful operation for basic and applied studies in observatory site assessment, atmospheric optics and environmental sciences. The ratio between these two quantities, also known as Posch ratio, has been previously studied for some canonical cases and reported for a few observational sites. In this work we (a) generalize the Posch ratio concept, extending it to any pair of radiance-related linear indicators, (b) describe its main algebraic properties, and (c) provide analytical expressions and numerical …
The use of high-quality simulated sky catalogs is essential for the success of cosmological surveys. The catalogs have diverse applications, such as investigating signatures of fundamental physics in cosmological observables, understanding the effect of systematic uncertainties on measured signals and testing mitigation strategies for reducing these uncertainties, aiding analysis pipeline development and testing, and survey strategy optimization. The list of applications is growing with improvements in the quality of the catalogs and the details that they can provide. Given the importance of s…
Differentiating between an exoplanet signal and residual speckle noise is a key challenge in high-contrast imaging. Speckles are due to a combination of fast, slow and static wavefront aberrations introduced by atmospheric turbulence and instrument optics. While wavefront control techniques developed over the last decade have shown promise in minimizing fast atmospheric residuals, slow and static aberrations such as non-common path aberrations (NCPAs) remain a key limiting factor for exoplanet detection. NCPA are not seen by the wavefront sensor (WFS) of the adaptive optics (AO) loop, hence th…
The Bayesian Global Sky Model (B-GSM): Validation of a Data Driven Bayesian Simultaneous Component Separation and Calibration Algorithm for EoR Foreground Modelling
The Earth's magnetic field induces Zeeman splitting of the magnetic dipole transitions of molecular oxygen in the atmosphere, which produces polarized emission in the millimeter-wave regime. This polarized emission is primarily circularly polarized and manifests as a foreground with a dipole-shaped sky pattern for polarization-sensitive ground-based cosmic microwave background experiments, such as the Cosmology Large Angular Scale Surveyor (CLASS), which is capable of measuring large angular scale circular polarization. Using atmospheric emission theory and radiative transfer formalisms, we mo…
We report the atmospheric turbulence parameters namely, atmospheric seeing, the tilt-anisoplanatic angle ($θ_0$) and the coherence time ($τ_0$), measured under various sky conditions, at Vainu Bappu Observatory in Kavalur. Bursts of short exposure images of selected stars were recorded with a high-speed, frame-transfer CCD mounted on the Cassegrain focus of a newly commissioned 1.3 m telescope. The estimated median seeing is $ \approx 1.85^{\prime\prime} $ at wavelength of $\sim 600$ nm, the image motion correlation between different pairs of stars is $\sim 44\%$ for $θ_0 \approx 36^{\prime\pr…
Nighttime monitoring of the aerosol content of the lower atmosphere is a challenging task, because appropriate reference natural light sources are lacking. Here we show that the anthropogenic night sky brightness due to city lights can be successfully used for estimating the aerosol optical depth of arbitrarily thick atmospheric layers. This method requires measuring the zenith night sky brightness with two detectors located at the limiting layer altitudes. Combined with an estimate of the overall atmospheric optical depth (available from ground-based measurements or specific satellite product…
We present long-term (4-10 years) trends of light pollution observed at 26 locations, covering rural, intermediate and urban sites, including the three major European metropolitan areas of Stockholm, Berlin and Vienna. Our analysis is based on i) night sky brightness (NSB) measurements obtained with Sky Quality Meters (SQMs) and ii) a rich set of atmospheric data products provided by the European Centre for Medium-Range Weather Forecasts. We describe the SQM data reduction routine in which we filter for moon- and clear-sky data and correct for the SQM "aging" effect using an updated version of…
Sky background accounting in spectral infrared observations of extended objects at the Caucasus Mountain Observatory of the SAI MSU
Sternberg Astronomical Institute, Lomonosov Moscow State University（列昂诺夫莫斯科国立大学斯特恩伯格天体物理研究所）；Faculty of Physics, Lomonosov Moscow State University（列昂诺夫莫斯科国立大学物理学院）；Institute of astronomy of Russian Academy of Sciences（俄罗斯科学院天体物理研究所）
Atmospheric Light Pollution by Proposed Reflect Orbital Space Mirrors
Slovak Academy of Sciences（斯洛伐克科学院）；Faculty of Mathematics, Physics and Informatics, Comenius University in Bratislava（布拉迪斯拉发康斯坦丁哲罗大学数学、物理与信息学院）；Department of Astrophysical Sciences, Princeton University（普林斯顿大学天体科学系）
QUIJOTE-TFGI polarization calibration -- Ground characterization and on-sky validation with Tau A and the Moon
Instituto de Astrofísica de Canarias（加那利天体物理学研究所）；Universidad de La Laguna (ULL)（拉古纳大学）；Instituto de Física de Cantabria (IFCA)（坎塔布里亚物理研究所）；Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo Institutes for Advanced Study, The University of Tokyo（东京大学前沿研究科 Kavli宇宙物理数学研究所）
We present the Strong Lensing Science Collaboration's (SLSC) recommended observing targets for the science verification and science validation phases of commissioning. Our recommendations have been developed in collaboration with the Dark Energy Science Collaboration (DESC) Strong Lensing Topical Team. In summary, our key recommendations are as follows: (1) Prioritize fields that span the full range of declination observable from Cerro Pachon during the engineering focused Science Verification phase of commissioning, before concentrating on equatorial fields for the Science Validation surveys.…
We present early laboratory simulations and extensive on-sky tests validating of the performance of a shaped pupil coronagraph (SPC) behind an extreme-AO corrected beam of the Subaru Coronagraphic Extreme Adaptive Optics (SCExAO) system. In tests with the SCExAO internal source/wavefront error simulator, the normalized intensity profile for the SPC degrades more slowly than for the Lyot coronagraph as low-order aberrations reduce the Strehl ratio from extremely high values (S.R. $\sim$ 0.93--0.99) to those characteristic of current ground-based extreme AO systems (S.R. $\sim$ 0.74--0.93) and t…
Light pollution is a worldwide phenomenon whose consequences for the natural environment and the human health are being intensively studied nowadays. Most published studies address issues related to light pollution inland. Coastal waters, however, are spaces of high environmental interest, due to their biodiversity richness and their economical significance. The elevated population density in coastal regions is accompanied by correspondingly large emissions of artificial light at night, whose role as an environmental stressor is increasingly being recognized. (...) At the same time, the marine…
