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By the late Qing dynasty, Western scientific learning had been disseminated among the Chinese literati. However, astronomical knowledge was still interpreted in the traditional Chinese astrological manner and served as an instrument in political affairs, especially in times of crisis. This paper examines controversies over astronomical observations between the proponents of traditional astrology and Western learning by presenting two cases of comet sightings. The first case is of a comet sighting between 1880 and 1882, and the second is of comets sighted before the Chinese Revolution of 1911. The reasons for the recurrence of ancient cometary prognostication in the early 20th century, when modern knowledge of comets was widespread in China, were explored as well. [ABSTRACT FROM AUTHOR]

Delingha 13.7 m telescope is one of the most important radio telescopes in China. Since installing the superconducting spectroscopic array receiver (SSAR) and adopting the On The Fly (OTF) observation mode, the telescope has operated for nearly 10 years. During this period, a large number of astronomical observation projects have been carried out and completed, a large amount of astronomical data have been accumulated, and a series of important scientific results have been achieved. This paper introduces the operating status of SSAR in astronomical observations, the problems in operations, as well as the fault phenomena and solutions. The performance test and performance analysis of SSAR are described in detail, including the receiver noise temperature and telescope system noise temperature, image rejection ratio (IRR), receiver stability, beam performance and so on. The updating and development of SSAR are listed, including the automatic adjustment of LO (Local Oscillator) power, the updating of pre-amplification circuits of the sideband separation superconducting mixer, and the optimization of control program, etc. This paper summarizes the experiences and rules, and connects the past with the future, for applying the experiences of the maintenance and operation of SSAR to the next-generation large-scale receiver system. [ABSTRACT FROM AUTHOR]

With the rapid development of population and urbanization and the progress of lighting technology, the influence of artificial light sources has increased. In this context, the problem of light pollution has attracted wide attention. Previous studies have revealed that light pollution can affect biological living environments, human physical and mental health, astronomical observations and many other aspects. Therefore, organizations internationally have begun to advocate for measures to prevent light pollution, many of which are recognized by the International Dark-Sky Association (IDA). In addition to improving public awareness, legal protections, technical treatments and other means, the construction of Dark Sky Reserves (DSR) has proven to be an effective preventive measure. So far, as a pioneer practice in this field, the IDA has identified 11 DSRs worldwide. Based on the DA requirements for DSRs, this paper utilizes NPP-VIIRS nighttime light data and other multi-source spatial data to analyze possible DSR sites in China. The land of China was divided into more than ten thousand 30 km × 30 km fishnets, and constraint and suitable conditions were designated, respectively, as light and cloud conditions, and scale, traffic and attractiveness conditions. Using a multiple criteria evaluation, 1443 fishnets were finally selected as most suitable sites for the construction of DSRs. Results found that less than 25% of China is not subject to light pollution, and less than 13% is suitable for DSR construction, primarily in western and northern areas, including Tibet, Xinjiang, Qinghai, Gansu and Inner Mongolia. [ABSTRACT FROM AUTHOR]

This paper reviewed the developments of the last ten years in the field of international high-resolution earth observation, and introduced the developmental status and plans for China's high-resolution earth observation program. In addition, this paper expounded the transformation mechanism and procedure from earth observation data to geospatial information and geographical knowledge, and examined the key scientific and technological issues, including earth observation networks, high-precision image positioning, image understanding, automatic spatial information extraction, and focus services. These analyses provide a new impetus for pushing the application of China's high-resolution earth observation system from a 'quantity' to 'quality' change, from China to the world, from providing products to providing online service. [ABSTRACT FROM AUTHOR]

Abstract: With aim to master early deformation stages and motion laws of landslide, the raw displacement data of landslide are very important for the landslide researchers and environmental scientists. With the recent advances of Global Position System (GPS) and computer science, the differential GPS technology now can be used for the remote displacement observation of landslide. Therefore, the paper developed a landslide displacement remote observation system based on differential GPS technology to get the raw displacement data continually. The system is divided into hardware and software functional segments. A real landslide in southwest of China was monitored for several months through observation using this GPS-based system placed around and the observed results are presented in this paper. The practical application shows that this system has such advantages as being highly-precise, nearly real-time, remote, continuous and automatic. [Copyright &y& Elsevier]

Abstract: The mutual eclipse of S4 Dione by S3 Tethys (Dec 23, 2009) and mutual occultation of S3 Tethys by S4 Dione (Apr 24, 2010) were observed at Yunnan Observatory during the international campaign in 2009–2010. The aim of this paper is to calculate the astrometric data of the involved Saturnian satellites during the mutual events, using a same dynamical model as proposed by Assafin et al. (2009) for the mutual occultation and a same one as proposed by Zhang and Liu (2011) for the mutual eclipse, and taking the scattering properties of the Saturnian satellites surfaces into account. Compared with the theory TASS 1.7 (Vienne and Duriez, 1995), the O–C(x) and O–C(y) are 10.1mas, 3.4mas for the mutual eclipse S4 by S3 and 28.4mas, −1.3mas for the mutual occultation S3 by S4, and with respect to the theory by Lainey et al. (2011), the results are 1.0mas, −5.0mas and −0.2mas, 2.5mas respectively. [Copyright &y& Elsevier]

Abstract: Recent development of multilayer mirror and its applications in extreme ultraviolet (EUV), soft X-ray ranges in China was reviewed in this paper. Three types of multilayer mirrors were developed with special performance for dense plasma diagnostics, EUV astronomical observation. Firstly, dual-periodic W/B4C multilayer mirror was designed for Kirkpatrick–Baez (K–B) microscopy working at TiKα line (4.75keV), which is highly reflective both at hard X-ray (CuKα line at 8.05keV) and soft X-ray (4.75keV). Using this mirror, the K–B system can be aligned conveniently in air using hard X-ray instead of in vacuum. The second mirror is aperiodic Mg/SiC multilayer, also a bi-functional mirror with high reflectivity for He-II emission line (30.4nm) but suppressing He-I emission line (58.4nm) in astronomy observation, which will replace the traditional combination of periodic multilayer and the fragile film filter. This will be more safe in satellite launching. The third mirror is Mo/Si periodic multilayer, depositing on a parabolic substrate with diameter of 230mm, which is designed for EUV telescope for imaging of solar corona by selecting Fe-XII emission (19.5nm). The uniformity of lateral layer thickness distribution is within ±0.3% along the diameter of mirror, measured by X-ray reflectometry. The measured peak reflectivity is 42% at the wavelength of 19.5nm. All these multilayer mirrors were prepared by using magnetron sputtering system in our group. [ABSTRACT FROM AUTHOR]

Abstract: Based on observations of two ionosondes at Wuhan and Kokubunji, this paper presents effects of TADs on the daytime mid-latitude ionosphere during the intense geomagnetic storm on March 31, 2001. During a positive ionospheric storm, the start of the enhancement of the foF2 (F2 peak plasma frequency) at Wuhan lags that at Kokubunji by 15min, which corresponds to the time interval of traveling atmospheric disturbances (TADs’) propagation from Kokubunji to Wuhan. Associated with the uplifting of the hmF2 (height of F2 peak) caused by TADs, it is observed by the two ionosondes that the F1 cusp becomes better developed. Therefore, during a geomagnetic storm, TADs originating from the auroral oval may have a strong influence on the shape of the electron density profile in the F1 region ionosphere at middle latitudes. It is highly likely that TADs are responsible for the evolution of the F1 cusp. [Copyright &y& Elsevier]

• Report on the construction of the first site of globe at night - sky brightness monitoring network in mainland China. • The first research report that reflect the variation and regional difference of night sky brightness in the economically developed regions of China (Yangtze River Delta). • The first research report on the construction of urban night sky monitoring network led by high school students. The rapid development of cities has brought tremendous pressure to astronomical observation, energy security, and the ecosystem. Automatic monitoring of night sky brightness (NSB) can help us to understand its regional differences and time variations of NSB effectively and to investigate the human and natural factors which lead to these changes. In this paper, the construction of Wuxi City night sky brightness monitoring network (WBMN) in China is presented. In addition to introducing the equipment and the installation of the network, a brief analysis of the data obtained from the stations will also be presented. The impact of human activities on the NSB is illustrated through its changes during the Spring Festival (lunar new year) and non-festival nights, and through a comparison study between NSB data taken from locations of different land usages. It is concluded that, while the reduction in human activities after non-festival midnights or the reduction in moon illumination near the new moon epoch led to darker night skies, brightening of the night skies may be attributed to firework displays during the nights of Spring Festival in 2019. On the other hand, the absence of firework during the Spring Festival in 2020 may explain the darker night skies. Finally, there is an evidence that the urban developments in Wuxi are degrading night sky quality. [ABSTRACT FROM AUTHOR]

We report 19 coobserved enhanced sodium layers, including sporadic sodium layers (SSLs) and thermospheric enhanced sodium layers (TeSLs), over Hefei (31.8°N, 117.3°E) and Wuhan (30.5°N, 114.4°E) from 2011 to 2018. The total coobservation time at Hefei and Wuhan was 387.24 hr, and the average occurrence rates were 0.038 hr−1 and 0.028 hr−1 for the SSLs and TeSLs, respectively. The SSL and TeSL occurrence rates in summer were 0.078 and 0.039 hr−1, respectively, which were considerably higher than those in other seasons. Among all 19 cases, 16 cases, including 9 SSL cases and 7 TeSL cases, occurred almost simultaneously over Hefei and Wuhan without a time delay. Seven TeSLs and four out of the nine SSLs were accompanied by ionospheric sporadic E (Es), suggesting that an "Es‐SSL (TeSL)" chain formed via the wave‐induced wind shear mechanism. Three SSLs were modulated by waves and the two other cases were related with gravity wave overturning. In general, the correlation coefficients between Hefei and Wuhan for long‐duration cases (more than 2 hr) were high due to some large‐scale mechanism, and the short‐duration cases (less than 2 hr) had poor correlation due to different local characteristics. In addition, three cases were observed with an apparent time delay over Hefei and Wuhan, which might indicate the possible existence of long‐distance transport processes. Key Points: Enhanced sodium layers observed between Hefei and Wuhan showed the consistency of the overall propagating and the difference in detailMost of the enhanced sodium layers were related with ionospheric sporadic E, one of which extended horizontally for nearly 1,000 kmFive sporadic sodium layer cases in the upper mesosphere, instead of relate with Es, are mainly generated by neutral dynamic process [ABSTRACT FROM AUTHOR]

The original idea of orbit determination called 'determination of satellite orbit by transfer' was proposed by the National Time Service Center, Chinese Academy of Sciences. It shows that the system is very stable and the orbit determination accuracy is improved greatly. A new observation mode called 'differenced ranges between master station and slave stations by transfer' is introduced. It is the development of 'determination of satellite orbit by transfer'. In principle, the differenced ranges between master station and slave stations have a high angular resolution, and strongly constrains in the transverse direction of satellite orbit, perpendicular to the line-of-sight. The principle of 'differenced ranges between master station and slave stations by transfer' is discussed in detail. And differenced ranges in combination with ranging data were used to determine satellite's orbit and orbit prediction under different arc observations. It shows that orbit determination accuracy for orbit prediction can be improved with differenced ranges in combination with ranging data. [ABSTRACT FROM AUTHOR]

Emissions of reactive nitrogen (N) species can affect surrounding ecosystems via atmospheric deposition. However, few long-term and multi-site measurements have focused on both the wet and the dry deposition of individual N species in large areas of Northern China. Thus, the magnitude of atmospheric deposition of various N species in Northern China remains uncertain. In this study, the wet and dry atmospheric deposition of different N species was investigated during a three-year observation campaign at ten selected sites in Northern China. The results indicate that N deposition levels in Northern China were high with a ten-site, three- year average of 60.6 kgNha-1 yr-1. The deposition levels showed spatial and temporal variation in the range of 28.5-100.4 kgNha-1 yr-1. Of the annual total deposition, 40% was deposited via precipitation, and the remaining 60% was comprised of dry-deposited forms. Compared with gaseous N species, particulate N species were not the major contributor of dry-deposited N; they contributed approximately 10% to the total flux. On an annual basis, oxidized species accounted for 21% of total N deposition, thereby implying that other forms of gaseous N, such as NH3, comprised a dominant portion of the total flux. The contribution of NODue to image rights restrictions, multiple line equation(s) cannot be graphically displayed. to N deposition was enhanced in certain urban and industrial areas, possibly due to the fossil fuse combustion. As expected, the total N deposition in Northern China was significantly larger than the values reported by national scale monitoring networks in Europe, North America and East Asia because of high rates of wet deposition and gaseous NH3 dry deposition. Taken together, these findings show that NH3 emissions should be abated to mitigate high N deposition and associated potential impacts on ecosystems in Northern China. The present results improve our understanding of spatio-temporal variations of magnitudes, pathways and species of deposited N in the target areas, and are important not only to inform conservation and regulatory bodies but also to initiate further detailed studies. Uncertainties among current observations underscore the need to quantify the impact of vegetation on dry deposition and to refine the simulation of dry deposition velocity. [ABSTRACT FROM AUTHOR]

The article reports that China will launch the first space Hard X-ray Modulation Telescope (HXMT) with a high space resolution and sensitivity in 2010 or 2011. It notes that telescope will perform and observe all-sky hard X-ray survey and cosmic X-ray sources. It states that the success in astronomical observation and discoveries will be achieved by China through the launch of HXMT. It also mentions that key technical difficulties of the telescope are settled.

No abstract received. [ABSTRACT FROM AUTHOR]