The explosion of energic solar activity is closely related to the current structure in the active region, Ampere's law j_z=1/μ(▽×B)_z is the theoretical basis for measuring the current density in the active region. Due to the inevitable existence of random noise in the measured vector magnetic field, the current density calculated by using the different form of Ampere's law is significantly different. In order to compare the differences between the calculated results of different form and explore one of the most practical current calculation methods, this article is based on the vector magnetogram in activity region AR11158 measured by SDO (Solar Dynamic Observatory)/HMI (Helioseismic and Magnetic Imager) on February 15, 2011. The distribution of the line-of-sight electric current density in the active region is calculated using differential algorithm and integral algorithm of Ampere's law. The results demonstrate that the distribution of line-of-sight electric current density j_z obtained by the differential algorithm is more severely affected by random noise than the result obtained by the integral algorithm, the current structures in the current distribution diagram obtained by the integral algorithm is much clearer than the former. In addition, the noise signal of the calculated current distribution map will decrease sharply, as enlarging the radius of the integral loop, the current structure in the obtained current distribution map will become clear. However, when the radius of the integral loop continues to expand, part of the fine structures of the current distribution map will also be distorted when obtaining a clear current distribution diagram. The result of this study demonstrates that the map of current distribution which is calculated by expanding the integral loop properly can reduce the effect on calculation results from random noise, and obtaining a clear and true line-of-sight electric current distribution map. Though the noise is eliminated if the radius of the integral path is too large, some fine structures in the current distribution will be lost. Therefore, during the course of actual calculating electric current. It is suggested to use high-resolution vector magnetogram and use the integral algorithm of Ampere's law to calculate the line-of-sight electric current in the active region by selecting an appropriate integration path, which can help us to explore the relationship between the eruptive flares and the structures of current in the active region.

Solar radio burst event (SRB) is an optional factor for wireless communications especially satellites navigation communications. The peak flux of the SRB event in 4th November reached 5 800 SFU (Solar Flux Unit) in 1 415 MHz. During this event, the GPS receivers in European and the Air navigation systems all suffered from stronge influences. In this paper, we analysed the relationship between X-ray flux variation and radio flux variation during this event. By comparing, the beginning time of X-ray flux upraising was 30 minutes earlier than radio flux. Furthermore, in this paper we discussed the background of phenomenon, the soft and hot X-rays correspond to hot and non-hot electron radiation, which is the physical condition that produces radio bursts that can cause such space weather events. The soft-to-hard process of X-rays can offer an effective early alarming method for this kind of space weather events.

The Five-hundred-meter Aperture Spherical radio Telescope (FAST) can change the shape of its illuminated area of the spherical reflector into a paraboloid of 300 m aperture, which realized the primary reflector antenna function of the telescope. The illuminated aperture of the telescope (the aperture of the paraboloid that changed from the spherical reflector) plays a key role in the performance of the telescope. In order to improve the potential performance and for the subsequent development of the telescope, as the illuminated aperture of FAST is 300 m and larger than 300 m, by calculating the shape-changing between paraboloid with different focal lengths and the reference spherical reflector, the analysis of the shape-changing from the spherical reflector to the paraboloid is carried out, and the feasibility of other illuminated aperture for the telescope is discussed. The focal length and the focal ratio of the paraboloid in the maximum movement distance of the actuator are given. In terms of the driving distance, the theoretical feasibility of the shape-changing is explored. The analysis is also applicable to the paraboloid of other apertures.

The receiver is cooled by helium of the 26 meter telescope at Nanshan in Xinjiang Astronomical Observatory, Chinese Academy of Sciences. The compressor need to be maintained regularly, the helium tube may leak due to wear. The condition of the compressor affects the normal observation of the 26 meter telescope. According to the actual demand of monitoring pressure of compressor, the compressor pressure monitoring system is designed and developed, it can realize the following functions, such as recording compressor pressure, real-time monitoring, real-time alarm, sending alarm information and daily report of compressor pressure by email, querying the historical work record of compressor, processing compressor alarm information and so on. This paper introduces the framework of the software system, the software flow the principle of data processing, the idea about how to realize the software system, the function of software module and the human-computer interface. The software has the following advantages, such as rapid alarm, powerful query function, simple and friendly human-computer interface, strong expansibility and other advantages, which can meet the needs of current and future applications.

The advantage is unique to observe the solar evolution and monitor solar activities by using the balloon-borne solar telescope launched into the stratosphere of the Earth's atmosphere. First of all, observation of the balloon-borne telescope in the stratosphere is not disturbed by the climate phenomena in the troposphere, and is in a seeing-free environment, which provides a wonderful condition for obtaining solar images of high quality. Second, the air in the stratosphere is very tenuous, and the absorption in the ultraviolet wavelength weakens apparently, so the balloon-borne telescope is able to observe solar activities and eruptions in the near-ultraviolet wavelength. Third, the cost could be low and the efficiency could be enhanced significantly by using the balloon-borne telescopes via recycling, upgrading, and reusing. This is much more economical and practical than by using the space-borne telescopes. It has been more than half a century since the balloon-borne telescope was first launched in the Europe and the USA. This work is going to briefly look back the history of the balloon-borne solar telescope missions, including the rich experience in the instrument development and observations. The payloads of the SUNRISE, an European balloon-borne solar telescope mission, are described in this work, and large amount of the high quality data obtained by the SUNRISE, as well as the consequent scientific articles produced on the basis of these data are also introduced. The information presented here would be valuable and important for reference in developing the balloon-borne telescope in China.

The non-sliding Lagrange interpolation method and sliding Lagrange interpolation method are used to interpolate the precise ephemeris of Beidou satellite navigation system (BDS). The relationship between interpolation accuracy and interpolation order of BDS satellite and two methods is studied. The results show that when non-sliding and sliding Lagrange interpolation are used respectively the interpolation errors of MEO and IGSO satellites are approximately U-shaped and L-shaped with the increase of the order, while the interpolation errors of GEO satellites increase gradually and are approximately stable with the increase of the order. When the interpolation order is low, the interpolation errors of the two methods have certain regularity, but the regularity of GEO satellite interpolation error is weaker than that of MEO satellite and IGSO satellite. The difference of the optimal interpolation order of the two methods for each satellite is within 1, and under the best interpolation order the accuracy of sliding Lagrange interpolation is 11.96%~44.01% higher than that of non-sliding interpolation, and the interpolation accuracy of GEO satellite is better than that of MEO satellite and IGSO satellite.

A two-mirror active optics system is established to simulate the relative pose relationship between the both segments. A pose detection method is proposed to detect the three Degrees of Freedom (DOFs), tip/tilt and piston, of the active segment. It is a combinational method of two edge sensors and a laser-CCD based tilt sensor. The theoretical control matrix and the measured control matrix are used to carry out active calibration experiments. The experiment shows that the maximum Root Mean Square (RMS) error of the edge sensors is about 7.4 nm and the tilt about 0.080″ when the theoretical control matrix is used. While the measured control matrix is used, the edge sensor's RMS error is about 7.3 nm, and the tilt about 0.076″. The research offers a potential solution to the problem of insufficient detection of the DOFs between the mirrors segmented in a ring.

In order to explore the primary mirror support of the Advanced Ground-based Solar Telescope (AST-G), this paper reported the development of the aligning system of an active optical mirror using CAN bus communication. Based on an active support system prototype, theoretical analysis of mirror kinematics with regard to the configuration of displacement actuators was firstly figured out. Then, a master node and three slave nodes were designed with STM32 to realize the distributed control of displacement actuators to actively align the mirror. Finally, we tested the performance of displacement actuator with CAN bus and the experimental verification of the mirror alignment. The results show that the control accuracy of the displacement actuator is better than 1 μm RMS, the rotations of the system around the x-axis and y-axis are better than 1″ RMS, and the piston error of the mirror is also better than 1 μm RMS. The research of the alignment system with CAN bus is an elementary technical preparation for future development of the primary mirror support system of the AST-G.

In recent years, using the atomic data measured by experimental devices to explain astronomical observational puzzles (including weak lines radiation, calibration of diagnostic characteristic lines ratio and anomalous lines flux ratio) has made great strides. In order to measure the high-resolution soft X-ray spectra of highly charged iron ions, an ultra-high vacuum flat field spectrometer is designed and built on the National Astronomical Observatories of the Chinese Academy of Sciences(NAOC) EBIS-A platform. In single-slit mode, the spectrometer uses 1 200 grooves/mm varied line-spacing diffraction grating in the wavelength range of 11.5-19.8 nm. With the same working principle of the electron beam ion trap, Heidelberg-EBIT ultraviolet spectrometer experiment data based on Chianti database is analyzed in the spectral region from 11.5 to 14.5 nm. First, a linear regression model is established to calibrate the offset of the peak position of line strength caused by the experimental system. Then the soft X-ray spectra of Fe ions in various ionization stage simulated by the collision radiation model identifies wavelengths of Fe VIII and Fe XIX-XXIII line radiation in experimental measurement. And the present simulations satisfactorily reproduce the measured spectra. Furthermore, blend lines of Fe XIX and Fe XX, which is weaker than the transition line of Fe XXIII, are found at 13.292 5 ±0.101 78 nm but the observed spectra has not resolved these weak lines. Therefore, the following experimental measurement can take the predicted results as a reference to test the performance of the spectrometer.

The radio pulse signal is affected by the interstellar medium during the transmission process, which will cause the profile to be broadened and deformed. In the research process, the signal needs to be de-dispersed. This paper designs and implements a zero-copy-based GPU coherent de-dispersion algorithm for pulsar data, uses device memory mapping to eliminate the copy cost from host to device, and uses CUDA's cuFFT library to perform multi-BATCH Fourier transform to improve DFT efficiency. Multithreading is used to realize the accelerated calculation of the transfer function. The experimental results show that, compared with traditional CPU and GPU algorithms, the algorithm proposed in this paper performs well in large amounts of data.

On June 21, 2020, an annular eclipse happened in China and the path went through Tibet, Sichuan, Chongqing, Hunan, Jiangxi, Fujian and Taiwan, partial solar eclipse could be observed in other areas. The solar telescope in Shenzhen Astronomical Observatory observed the whole process of the partial solar eclipse. At the same time, the meteorological equipment settled in the observatory obtained solar radiation, temperature, relative humidity, air pressure and other meteorological elements. The analysis of the observational data during the eclipse shows that:(1) solar radiation, temperature and air pressure declined and then ascended slowly from the first contact to maximum of eclipse. Because of the weather, the minimum time lagged behind to the time of eclipse maximum. The time of solar radiation lagged behind by 1.37 minutes, temperature lagged behind by 6.37 minutes and air pressure lagged behind by 10.37 minutes. (2) From the first contact to maximum of eclipse, the relative humidity ascended to the maximum value, lasted for 33 minutes, and then decreased. The maximum time lagged behind the time of eclipse maximum by 6.37 minutes. (3) Comparing the variation of meteorological parameters in the days before and after the solar eclipse, the rate of variation of solar radiation, temperature and relative humidity during the solar eclipse was about one order of magnitude higher than that without the solar eclipse. The variation of air pressure with/without solar eclipse was nearly same. (4) During the solar eclipse, the correlation between the relative intensity of the solar disk and meteorological parameters was strong, with the pearson correlation coefficient are 0.95, 0.89, -0.82 and 0.75, respectively.

The YNAO Multi-function Astronomical Theodolite II is a ground-based astrometric telescope. Two telescopes form the observation network with the first generation YNAO Multi-function Astronomical Theodolite to monitor the variation of plumb line of observing site. Its main imaging devices are three digital CCD cameras without cooling, which work in external trigger mode. When the telescope is observing, three sets of triggering signals are generated from the telescope control system, for controlling three digital CCD cameras, respectively. In the paper, the detailed information of the telescope operation mode is showed, and an introduction to workflow of the image acquisition system is given. The details of hardware constitution, software framework and main programming methods of software are also given. For demonstrating the effectiveness of the system, a screenshot of the user interface of the software, some images acquired by the cameras, and an analysis of a stellar image recorded by the camera are provided.

With the progress of sky survey projects, traditional database technology cannot satisfy the requirements of massive astronomical data storage and retrieval performance. In this paper, aiming at the high concurrency and performance of massive astronomical data storage and cone search, database middleware technology is used. When massive data reaches the limit of traditional database storage, it can be stored in the form of sub-database and sub-table through middleware technology. In the database cluster, the characteristics of the relational databases and distributed technology are fully integrated. In this article, with the application of MySQL database integrated DIF plug-in technology a pseudo-spherical index in a distributed database is established, which can meet the needs of spatial indexing in massive astronomical data.

Based on maximum entropy spectral estimation method, this paper analyzes the periodic characteristics of the high-energy electron flux ≥ 2.0 MeV which has been observed by FY-2D meteorological satellite.The algorithm is based on the autocorrelation model (AR), a period of 13.87 d and 27.8 d is deduced by analyzing the power spectrum. According to the FPE and AIC criteria, the parameters of the AR model can be determined. Levinson-Durbin algorithm and Burg algorithm are compared with the maximum entropy spectral estimation method, it is found that maximum entropy spectral estimation has advantages in the study of periodic characteristics.The results are very important for the study of the spatial distribution of high-energy electrons in geosynchronous orbit,to forecast high energy electron flux enhancement events,or early warning of deep charging events.

All-sky imager (ASI) images are an important means for the astronomy community to monitor cloud cover at present, but there is no definite cloud cover calculation index. Therefore, this paper proposes a new quantitative index for cloud amount measurement-Cloud Distribution Density of ASI images (ASICDD), and establishes an automatic classification system for ASI images based on this index. Firstly, all the images in the dataset from the Key Laboratory of Optical Astronomy at the National Astronomical Observatories of Chinese Academy of Sciences (CAS) are denoised and the cloud area is segmented from the sky by OTSU algorithm. Secondly, the cloud amount for ASI image with the background remove is calculated by ASICDD proposed in this paper. Finally, we use four traditional classifiers (SVM, KNN, Decision Tree and Random Forest) to classify ASI images automatically according to the calculated value and evaluate the performance of each classifier. The results show that ASICDD can be used as a numerical index for judging the cloud cover of ASI images; the automatic ASI images classification system based on ASICDD achieves a high recognition accuracy rate. Meanwhile Random Forest has the best classification effect-the recognition accuracy rate of various cloud images has reached more than 95%.

Historical record on the Zhongkang solar eclipse may be the earliest record of solar eclipse in human history. Unfortunately, the date of the solar eclipse wasn't given in the record. The Xia-Shang-Zhou Chronology Project thought that the eclipse may occur on October 3, 2043 BCE, December 6, 2019 BCE, November 5, 1970 BCE, or October 26, 1961 BCE. The authors use the modern astronomical planetary ephemeris released by the NASA's Jet Propulsion Laboratory (JPL) to calculate distribution of the Zhongkang solar eclipse path and visibility of the eclipse in Zhenxun, capital of the Xia dynasty. The visibility in Zhenxun supports the possible occurrence time of the eclipse given by the Xia-Shang-Zhou Chronology Project. This work also provides a certain reference for the further study of the Zhongkang solar eclipse.