The analysis of the night cloud cover is very important for astronomical observation in real time, considering a typical observation time of about 15 minutes, and to have a statistics of the night cloud cover. In this paper we use the SQM (Sky Quality Meter) for high resolution temporal analysis of the La Silla and Asiago (Ekar observatory) sky: 3 and 5 minutes respectively. We investigate the annual temporal evolution of the natural contributions of the sky in a site not influenced by artificial light at night (ALAN) and one highly influenced respectively. We also make a correlation between GOES and AQUA satellites data and ground-based SQM data to confirm a relationship between the SQM data and cloud cover. We develop an algorithm that allows the use of the SQM for night cloud detection and we reach a correlation of 97.2\% at La Silla and 94.6\% at Asiago with the nighttime cloud cover detected by the GOES and AQUA satellites. Our algorithm also classifies the photometric (PN) and spectroscopic nights (SN). We measure 59.1\% PN and 21.7\% SN for a total percentage of clear nights of 80.8\% at La Silla in 2018. The respective Ekar observatory values are 31.1\% PN, 24.0\% SN and 55.1\% of total clear nights time. Application to the SQM network would involve the development of long-term statistics and big data forecasting models, for site testing and real-time astronomical observation.
The fraction of observable nights is an essential parameter for selecting astronomical sites. In recent years, meteorological satellite data have played an essential role in recognising and providing statistics of observable nights. We present a method to estimate the fraction of observable nights based on the FengYun-2 series of geostationary meteorological satellites and weather records of multiple astronomical sites. We have calculated the fraction of observable nights at 27 sites in Indonesia and two astronomical sites in China to validate the method. The results derived from our method sh…
Ground-based optical astronomy necessarily involves sensing the light of astronomical objects along with the contributions of many natural sources ranging from the Earth's atmosphere to cosmological light. In addition, astronomers have long contended with artificial light pollution that further adds to the 'background' against which astronomical objects are seen. Understanding the brightness of the night sky is therefore fundamental to astronomy. The last comprehensive review of this subject was nearly a half-century ago, and we have learned much about both the natural and artificial night sky…
The sustained increase of emissions of artificial light is causing a progressive brightening of the night sky in most of the world. This process represents a threat for the long-term sustainability of the scientific and educational activity of ground-based astronomical observatories operating in the optical range. Huge investments in building, scientific and technical workforce, equipment and maintenance can be at risk if the increasing light pollution levels hinder the capability of carrying out the top-level scientific observations for which these key scientific infrastructures were built. I…
Identification of Potential Sites for Astronomical Observations in Northern South-America
在这项研究中，我们描述了一种创新的方法，以确定潜在的网站在南美洲北部的安第斯山脉地区的光学和红外天文观测。该方法通过与气象站长期记录的温度和无线电探空仪的大气温度廓线的比较，计算了2008-12年地球同步环境观测卫星（GOES）数据的晴空分数（CSF）。为两个红外GOES通道建立了天空净空标准，以确定南美洲北部安第斯地区的潜在地点。该方法使用委内瑞拉国家天文台（Observatorio Nacional de Llano del Hato）报告的观测小时数进行了验证。单独的CSF百分比计算旱季和雨季的光度和光谱夜间质量。12个站点的五年平均CSF的光谱夜大于30%，在旱季被认为是适合天文观测。每年有220个$\pm$ 42分光晴朗夜晚的最佳地点位于委内瑞拉的安第斯山脉（70 $^{\circ}$ 28'48“W，9 $^{\circ}$ 5' 60“N），海拔3480米。在Sierra Nevada de Santamán和Serranía del Perijá发现了较低质量的地区，每年分别有（126 $\pm$ 34）和（111 $\pm$ 27）个晴朗的夜晚。安第斯山脉上的站点在北桑坦德省（107 $\pm$ 23）和博亚卡东北部地区（94 $\pm$ 13），每年的平均晴朗夜晚。两个网站在低纬度位于厄瓜多尔，每年有超过100个晴朗的夜晚，并与类似的季节性CSF百分比也确定。五…
Our team at the INAF-Astronomical Observatory of Padova and the University of Padova is engaged in the design, construction and operations of instruments with very high time accuracy in the optical band for applications to High Time Resolution Astrophysics and Quantum Astronomy. Two instruments were built to perform photon counting with sub-nanosecond temporal accuracy, Aqueye+ and Iqueye. Aqueye+ is regularly mounted at the 1.8m Copernicus telescope in Asiago, while Iqueye was mounted at several 4m class telescopes around the world and is now attached through the Iqueye Fiber Interface at the…
Seeing, the angular size of stellar images blurred by atmospheric turbulence, is a critical parameter used to assess the quality of astronomical sites. Median values at the best mid-latitude sites are generally in the range of 0.6--0.8\,arcsec. Sites on the Antarctic plateau are characterized by comparatively-weak turbulence in the free-atmosphere above a strong but thin boundary layer. The median seeing at Dome C is estimated to be 0.23--0.36 arcsec above a boundary layer that has a typical height of 30\,m. At Dome A and F, the only previous seeing measurements were made during daytime. Here …
We installed two sets of Astronomical Site Monitoring System(ASMS) at Lijiang Observatory(GMG), for the running of the 2.4-meter Lijiang optical telescope(LJT) and the 1.6-meter Multi-channel Photometric Survey Telescope (Mephisto). The Mephistro is under construction. ASMS has been running on robotic mode since 2017. The core instruments: Cloud Sensor, All-Sky Camera and Autonomous-DIMM that are developed by our group, together with the commercial Meteorological Station and Sky Quality Meter, are combined into the astronomical optical site monitoring system. The new Cloud Sensor's Cloud-Clear…
The Legacy Survey of Space and Time, operated by the Vera C. Rubin Observatory, is a 10-year astronomical survey due to start operations in 2022 that will image half the sky every three nights. LSST will produce ~20TB of raw data per night which will be calibrated and analyzed in almost real time. Given the volume of LSST data, the traditional subset-download-process paradigm of data reprocessing faces significant challenges. We describe here, the first steps towards a gateway for astronomical science that would enable astronomers to analyze images and catalogs at scale. In this first step we …
In 2018, Solar Cycle 24 entered into a solar minimum phase. During this period, 11 million zenithal night sky brightness (NSB) data were collected at different dark sites around the planet, including astronomical observatories and natural protected areas, with identical broadband Telescope Encoder and Sky Sensor photometers (based on the Unihedron Sky Quality Meter TSL237 sensor). A detailed observational review of the multiple effects that contribute to the NSB measurement has been conducted with optimal filters designed to avoid brightening effects by the Sun, the Moon, clouds, and other ast…
The photometric system of the One-meter Telescope at Weihai Observatory of Shandong University
山东大学威海天文台的一米望远镜是f/8卡塞格伦望远镜。三套滤光片，包括Johnson--UBVRI、Sloan Digital Sky Survey u $'$ g $'$ r $'$ i $'$ z $'$和Strömgren uvby，安装在双层滤光轮中。介绍了测光系统和CCD相机，详细分析了它们的性能，并确定了相关参数，包括CCD相机的增益、读出噪声、暗电流和线性度。此外，根据2007年9月至2013年8月收集的数据，系统地研究了该站点的天文气候条件特征，包括典型视宁度、晴朗夜晚统计和平均天空亮度，并在本工作中报告。利用8个夜晚的Landolt标准星观测数据进行了光度定标，得到了转换系数、光度精度和系统吞吐量。使用导出的校准参数和世界卫生组织的经典观测条件模拟了极限星等。
The effect of satellite constellations on observations in the visible and IR domains is estimated, considering 18 constellations in development by SpaceX, Amazon, OneWeb, and others, with over 26,000 satellites, constituting a representative distribution. This study uses a series of simplifications and assumptions to obtain conservative, order-of-magnitude estimates of the effects. The number of illuminated satellites from the constellations above the horizon ranges from ~1600 right after sunset, decreasing to 1100 at the end of astronomical twilight, most of them (~85%) close to the horizon (…
The population of artificial satellites and space debris orbiting the Earth imposes non-negligible constraints on both space operations and ground-based optical and radio astronomy. The ongoing deployment of several satellite `mega-constellations' in the 2020s represents an additional threat that raises significant concerns. The expected severity of its unwanted consequences is still under study, including radio interference and information loss by satellite streaks appearing in science images. In this Letter, we report a new skyglow effect produced by space objects: increased night sky bright…
Forecast of the atmospheric parameters and optical turbulence applied to the ground-based astronomy is very crucial mainly for the queue scheduling. So far, most efforts have been addressed by our group in developing algorithms for the optical turbulence (CN2) and annexed integrated astroclimatic parameters and quantifying the performances of the Astro-Meso-Nh package in reconstructing such parameters. Besides, intensive analyses on the Meso-Nh performances= in reconstructing atmospheric parameters relevant for the ground-based astronomy has been carried out. Our studies referred always to the…
The new SAI MSU observatory 2.5-meter telescope and capabilities of its current instrumentation are described. The facility operates actively since 2014 in parallel to the engineering works. It has delivered a number of prominent results in the field of optical and near-infrared photometry and spectroscopy as well as newly developed observational techniques like differential speckle polarimetry.
The rising population of artificial satellites and associated debris in low-altitude orbits is increasing the overall brightness of the night sky, threatening ground-based astronomy as well as a diversity of stakeholders and ecosystems reliant on dark skies. We present calculations of the potentially large rise in global sky brightness from space objects, including qualitative and quantitative assessments of how professional astronomy may be affected. Debris proliferation is of special concern: since all log-decades in debris size contribute approximately the same amount of night sky radiance,…
The Nanshan One-meter Wide-field Telescope (NOWT) is a prime focus system located at Nanshan Station of Xinjiang Astronomical Observatories (XAO). The field of view(FOV) was designed to 1.5 degree *1.5 degree, and Johnson-Cousins UBVRI system was chosen as the main Filter set. The telescope has been providing observation services for astronomers since Sept. 2013. Variable source searching and time-domain surveys are the main scientific goals. The system's test results are reported including linearity, dark current, bias, readout noise and gain of the CCD camera. The accurate instrumental calib…
We describe the Arizona-NOIRLab Temporal Analysis and Response to Events System (ANTARES), a software instrument designed to process large-scale streams of astronomical time-domain alerts. With the advent of large-format CCDs on wide-field imaging telescopes, time-domain surveys now routinely discover tens of thousands of new events each night, more than can be evaluated by astronomers alone. The ANTARES event broker will process alerts, annotating them with catalog associations and filtering them to distinguish customizable subsets of events. We describe the data model of the system, the over…
The main features of SG-WAS (SkyGlow Wireless Autonomous Sensor), a low-cost device for measuring Night Sky Brightness (NSB), are presented. SG-WAS is based on the TSL237 sensor --like the Unihedron Sky Quality Meter (SQM) or the STARS4ALL Telescope Encoder and Sky Sensor (TESS)--, with wireless communication (LoRa, WiFi, or LTE-M) and solar-powered rechargeable batteries. Field tests have been performed on its autonomy, proving that it can go up to 20 days without direct solar irradiance and remain hibernating after that for at least \mbox{4 months}, returning to operation once re-illuminated…
The Impact of Artificial Space Objects on Optical Astronomy as Determined from 32 Million Photometric Observations
IAU Centre for the Protection of the Dark and Quiet Sky（国际天文联合会保护黑暗与宁静天空中心）；Czech Academy of Sciences（捷克科学院）；Institute of Physics, Czech Academy of Sciences（捷克科学院物理研究所）
Analysis of Laser-Satellite Deconfliction for Astronomical Observatories
Institute for Astronomy, University of Hawaii at Manoa（夏威夷大学马诺阿分校天文研究所）；California Institute of Technology（加州理工学院）；Subaru Telescope, National Astronomical Observatory of Japan（日本国立天文台昴星团望远镜）；W. M. Keck Observatory（W.M.凯克天文台）
Atmospheric turbulence profiling with the Multistar Turbulence Monitor
School of Physics and Astronomy, Sun Yat-Sen University（中山大学物理学院）；Yunnan Observatory, Chinese Academy of Sciences (CAS)（中国科学院云南天文台）；Department of Physics and Astronomy, University of British Columbia（不列颠哥伦比亚大学物理与天文学系）；National Astronomical Observatories, Chinese Academy of Sciences（中国科学院国家天文台）；School of Physical Science and Technology, Southwest Jiaotong University（西南交通大学物理科学与技术学院）
Protecting the Dark Skies of Chile: Initiatives, Education and Coordination
在未来十年，智利将巩固其作为“世界天文学之都”的地位。到2025年，世界上70%以上用于进行专业天文观测的基础设施将安装在该国北部的阿塔卡马沙漠。这些望远镜产生的惊人的科学发现对我们对宇宙的理解有直接的影响，保护这个“宇宙之窗”是确保人类思考夜空和破译我们起源的权利的基础。作为一个国家，智利面临着打击光污染和保护其黑暗天空的挑战，因为城市不断扩大，采矿业不断扩大，与天文观测站共享同一领土。智利天文学会（Sociedad Chilena de Astronomia，SOCHIAS）通过一系列涉及教育计划的举措，在保护黑暗天空方面发挥着积极作用，帮助制定和执行公共政策和法规，并寻求将智利最好的天文遗址宣布为国家和国际两级的遗产保护区。在描述我们的经验时，我强调了从各个方面解决光污染问题的重要性，涉及所有相关参与者（社区，国家和地方政府，照明行业，环保主义者，天文学家等）。我还讨论了如何与潜在的问题行为者（如工业，城市和一些政府机构）进行沟通和及时协调，可以成为一种有效的工具，将潜在的敌人转化为保护夜空的盟友。
The Infrared Astronomical Characteristics of Roque de los Muchachos Observatory: precipitable water vapor statistics
本文介绍了由全球定位系统（GPS）获得的Roque de los Muchachos天文台（ORM）上空的大气水汽含量。通过与940 nm辐射计观测值的比较，对GPS测量值进行了评价。GPS测量的统计分析点ORM作为一个观测站点，具有合适的条件，红外（IR）观测，可降水量（PWV）的中位数柱为3.8毫米。PWV呈现出明显的季节性行为，冬季和春季的最佳季节红外观测。2、3、4月夜间PWV值小于3mm的占60%以上。我们还估计了ORM水汽含量的时间变化。PWV的统计结果在不同的天文网站的摘要，回顾这些值是不直接可比的，因为所使用的技术来记录数据的差异。
