White Dwarfs (WDs) are the final stage of the evolution of the majority of low-and medium-mass stars with initial mass <8M_⊙. Approximately 75% of all observed WDs are DA type. The spectra of DA white dwarf are dominated with Balmer Hydrogen lines. It is very difficult to measure the APP radial velocity of WDs by the line center because of the wide and asymmetry spectral profile. The kinematics of WDs is very important to distinguish populations of WDs. This paper presents a method for APP radial velocity measurement using cross-correlation between the observed spectrum and the template spectrum that has similar parameters, which has advantage than line center method, and the template spectra are from theoretical spectra by Koster et al. The final radial velocity is derived by the difference of APP radial velocity and the gravitational redshift. After test with simulated spectrum, the accuracy is within 10km/s for DA white dwarfs with T_eff higher than 10000K and SNR larger than 20. In addition, the radial velocities of observed DA WDs from SDSS DR7 are measured with the above method. The average radial velocities of these close DA white dwarfs (distance <1000pc) are approaching zero.

It's urgent to carry out high-performance scientific data processing with a single machine in the development and application of astronomical software. However, due to the different configurations of machines, the traditional CUDA + GPU technology has obvious limitations in portability and seamlessness. According to gridding algorithm in MingantU SpEctral Radioheliograph (MUSER) data processing, the OpenCL technology is used in parallel to implement multi-thread programming. The experimental results show that the gridding algorithm based on OpenCL can not only run on GPU, but also merely on CPU. While choosing execution on GPU, the execution efficiency of gridding algorithm is approximately equal to that on CUDA. At the same time, the algorithm is not limited to the NVIDIA's GPU, which has solved the problem of environmental dependence of CUDA + GPU. And the algorithm also has an acceptable execution efficiency in implementation with the merely CPU, which is suitable for development and testing astronomy software with a single machine and will facilitate the application and promotion of astronomical software.

Spreading through in the interstellar space,pulsar signals, due to the existence of the interstellar medium, would be observed dispersively, therefore we need to remove dispersion of the received pulsar signals for obtaining the original pulsar signals. The current de-dispersion methods are mainly divided into two types, coherent de-dispersion and incoherent de-dispersion. Relatively speaking, the former is able to eliminate dispersion completely, which has simpler algorithm, and preserves the time resolution of the original signal. Although it has a larger amount of calculation, rapid progress of computer technology can solve such problem. In order to accurately understand the difference between the two methods of de-dispersion, this paper, adopting the method of coherence coefficient, quantitatively compares the effects of coherent de-dispersion and incoherent de-dispersion:below a certain frequency, the former is better than the latter in obtaining the de-dispersion effects. Meanwhile, the observed frequency of the two de-dispersion methods at the same effect is determined.

Prediction for laser ranging of non-cooperative target is extrapolated from the Two Line Elements (TLE) normally, which has relatively large deviation and affects the success rate of laser ranging mission. Based on the orbital theory and the measured data of space target, the deviation of the forecast is mainly due to the deviation of mean anomaly from the prediction model and the real mean anomaly of the spatial target in the orbit. According to the target's miss distance in the field of view of tracking telescope, the relative algorithm can be used to find the optimal time element deviation to correct the mean anomaly of the spatial target. After modification, the visual position deviation of the space target is improved, the distance deviation can be reduced from several hundred meters to tens of meters, which makes the echo arrival time expectation more accurate, and can provide a more precise range gate control for the single-photon detector, and improves the mission success rate of laser ranging.

The growing number of miniaturized satellites or small-body space debris is a challenging problem for autonomous ground-based space object observation. Although most space objects larger than 10 cm in diameter have been catalogued by North American Aerospace Defense Command, the precise orbital information of each space object (based on six orbital parameters) remains important and should be maintained periodically due to orbital perturbations. In the past decades, modern ground-based Electro-optic telescopes equipped with electronic detectors have been widely used in astrometry engineering.The tracking performance of this equipment primarily depends on the size and brightness of the space target. Moreover, in the real-time observation procedure based on STARE tracking mode in a short exposure time, the space object and stellar background will similarly appear in the point-spread function with different levels of signal-to-noise ratio under the variable conditions of background interference, which is difficult to recognize. The aim of present work is to achieve high-sensitivity detection and improved tracking ability for non-Gaussian and dynamic backgrounds with a simple mechanism and computational efficiency. To overcome this limitation, we emphasize robust tracking of small size satellite and faint object via a state estimation technique. We proposed a neural-network based adaptive running Gaussian average algorithm to extract a moving space object from the stellar background and its interference. The algorithm was integrated to a Track-before-Detect (TBD) framework which used Monte-Carlo based particle filter. The integrated algorithms were adopted to track the space object. Three sequential astronomical image datasets taken by the Asia-Pacific Ground-Based Optical Space Object Observation System (APOSOS) telescopes under different conditions were used to evaluate the tracking strategy. The results showed that the scheme achieved a satisfying tracking performance.

To simulate the positional relationship between the Moon and the relay satellite ‘magpie bridge’ in a halo orbit around L₂ of the Earth-Moon system, then to evaluate the laser ranging success probability, in this paper we make a computation on the halo orbit with a request of about 14 days in its period, and establish a model given the tremble of the telescope, of the atmosphere and the transverse deviation from the predicted orbit. A numerical halo orbit is given with the period of 14.78 days, the amplitude is 12493km in X (along the Earth-moon connection direction), 34596km in Y, and 11916km in Z (orthogonal to the Earth-moon orbital plane). The minimum amplitude of the calculated halo orbit goes far beyond the Moon-sheltered critical amplitude which is generally 4000km, thus no shade from the Moon exists on the relay satellite. Based on the model of laser ranging success probability established previously, we make an analysis on the success probability according to the laser ranging system at KUNL station (International ID:7820), and the results indicate that the laser ranging success probability rapidly drops down with the increase of the orbit transverse standard deviation. For the average distance from the station to the relay satellite, the detector produces about 0.151 photoelectrons within a single pulse and the corresponding success probability is 14.07% when there is no deviation from the predicted orbit; the number of photoelectrons drops down to 0.035 and the corresponding success probability down to 3.46% when the relay satellite transversely deviates 2km from the predicted orbit. Comparing between the nearest distance and the furthermost distance, with no deviation, the number of photoelectrons declines to 0.139 from 0.174 and the corresponding success probability shrinks to 13.02% from 16.01%. The results provide a reference for the realization of the relay satellite laser ranging with 1.2m telescope at Yunnan Observatory in the following days.

Interpolating precision ephemeris is a fundamental task in the high-precision processing of satellite positioning data.In this paper, Lagrange polynomial interpolation method is used to analyze the precision of BDS precision ephemeris from three aspects, which are namely the interpolation accuracy of non-sliding Lagrange interpolation method in different interpolation orders, the sliding Lagrange interpolation method in different interpolation orders and the non-sliding and sliding Lagrange interpolation methods in the same interpolation order. Example results show:if the interpolation order is taken as the abscissa with rightward as positive and the interpolation accuracy is taken as the ordinate with upward as positive, the interpolation accuracy and interpolation order of non-sliding Lagrange interpolation show an parabolic curve which opens downward. When the interpolation order of the sliding Lagrange interpolation method takes above 7, the interpolation accuracy is in a stable and high state. The maximum value of interpolation error is about 1.1mm, and the mean square error is about 0.4mm; In the same interpolation order, the accuracy of sliding Lagrange interpolation is higher than that of non-sliding Lagrange interpolation.

Fabry-Perot Interferometers has been more and more widely used in China's astronomical community. At present, the Fuxian Lake Solar Observatory at the Yunnan Observatory has purchased two FPI for use in the spectral observation of the 1m new vacuum solar telescope. As the domestic research on FPI is still relatively small, overseas inquiries to relevant information is not yet accessable. Therefore, understanding its control system is not only needed to research FPI, but also the necessary foundation in daily work. In this paper, a basic review of FPI control system is given, and research is carried out on the analog-digital converting accuracy requirements in the digital front-end of the control system. We calculate the accuracy of the F-P parallel board control and finally select the AD converter that meets the requirements.

Spherical distance (Angular separation) calculation is commonly using in Astronomy and Geography. It is the foundation of object detecting, data query and cross-matching. The spherical distance can be computed by Spherical Geometry method, and people have deduced many formulas. But the precision of computer is limited, due to rounding error in the numerical computation. This article will inspect several widely used formulas, test and compare their results, and discuss their advantage and disadvantage. In addition, this article will demonstrate how to do distance calculation on several astronomical packages and databases. The purpose of this article is to help astronomers to find the suitable method to do their calculation.

Image simulation has played an increasingly important role in astronomical research. There are several important effects as follow:Through simulation, important basis for the evaluation of astronomical observation equipment can be provided; Data processing algorithm can be verified through the processing of simulation data. In this paper, we describe the whole process of image simulation and optimize the local methods of image simulation, so that the simulation results can be generated efficiently and accurately. The main work of this paper includes the following aspects:Simulation for astronomical objects, including point sources (such as stars) and extended source (galaxies), and mainly the introduction of the galaxy simulation; Simulation of observation conditions, mainly including instrument noise, stray light etc.; Simulation of optical system character which shows in image as point spread function (PSF); Optimization of calculation flow from calculations and procedural methods; Analysis for extracted galaxies sample. The data used in this paper is Hubble Ultra Deep Space (HUDF) ACS WFC i-band (F775) data with a limit of magnitude equal to 29 AB Mag. Through the analysis of the simulation results, we can see that the method can simulate the galaxies images quickly and accurately.

In the astronomy field, the estimation of cloud amount has an important influence on telescope observation.To monitor the cloud amount, it is a widely method to use all-sky cameras to capture cloud images. At present, the estimation of cloud amount is still completely by man power, which is very time-consuming and inaccurate; and the process of discrimination is entirely dependent on personal experience. Therefore, this paper presents an automatic processing method for all-sky images. The method first uses time segmentation and difference method to remove the moon influence regions in the cloud images respectively. Then the cloud and background are segmented by threshold method of the cloudy image after the removal of the affected regions of the moon. The clustering algorithm based on gray value is used to quantify the thickness of clouds in partly cloudy images. Finally, the total cloud amount is calculated and the cloud images are automatically classified according to the method of interpreting the all-sky camera cloud images based on TMT (Thirty Meters Telescope). The experimental results show that this method can greatly improve the efficiency of cloud images interpretation, while effectively saves man power; it also achieves a high recognition accuracy of 76.67%.

Stellar Abundance and Galactic Evolution (SAGE) photometric system is a self-designed system, which can provide accurate stellar atmosphere parameters and extinction. The actual 100σ depths of the single-epoch images are u_SC~17.3 and v_SAGE~16.8 (AB magnitude). We are performing a SAGE photometric sky survey of the northern sky, covering about 12000 squared degrees and over 500 million stars. This will be valuable data in research of the Milky Way. This paper introduces the research and development of the pipeline for the survey, particularly the data reduction process of a single exposure. The procedures include bias and flat correction, astrometric calibration, photometry and flux calibration. This paper also introduces the main results and data quality produced by the pipeline.

The new generation of observational technology in astronomy is driving a growth explosion in observational data. However, the traditional direct attaching storage device can hardly meet the needs of real-time storage and maga data processing. Although the distributed storage system based on inexpensive hardware is an effective approach, the high failure rates of the hardware seriously limit the application of these distributed storage devices in scientific data storage. Therefore, the method of generating two or more full copies is becoming a practical method to guarantee the reliability of the data files. In this paper, aiming to the replication of the large-size (>1MB) flexible image transmission formats (FITS) astronomical data file, we present a replication algorithm for the file size from one to dozens of MB range. The algorithm sacrifices the storage delay for the acquirement of the strong consistency with multiple copies in the conditions of multiple hardware and software exceptions. The experimental result shows the validity of the algorithm.

The atmospheric seeing is an important index to measure the atmospheric optical quality of the site. The Differential Image Motion Monitor (DIMM) is widely used for site testing at home and abroad. For example, ESO DIMM was implied in site testing for Europe Southern Observatory. This paper introduced an excellent method of seeing measurement:Improved to Differential Image Motion Monitor (I-DIMM). Firstly, the structure design of I-DIMM and seeing calculation method were described in details. After that, followed by setting the two telescopes, of which one's diameter is 0.36m and the other is 0.12m, this paper compared the calculated values of seeing in these two situations. Both results showed that calculating seeing by method I-DIMM was more accurate than DIMM. Finally, this paper analyzed both simulation results and introduced the advantages of I-DIMM compared to DIMM.

With the development of astronomical technology, the demand for astronomical data processing software is changing constantly, resulting in the complexity of software running environment. For developers and users, it is urgent to find a method for agile packaging and deployment of complex astronomical data processing software. Mingantu Ultrawide Spectral Radio Heliograph (MUSER) has been used for routine observation, and the data processing software for MUSER project has also been completed and put into use. As the deployment of this software involves the configuration problems of the operating system environment, the GPU running environment and the underlying dependence on software, the installation process is cumbersome and error-prone. According to the characteristics of container technology, in this paper we present a method of agile packaging and deployment for MUSER software system based on Docker container, and the design of this method is introduced. We verify the usability of this method by experiments, and the superior performance can be obtained by comparing with the traditional virtual machine. The method proposed in this paper can provide a reference for the future deployment and encapsulation of astronomical data processing software. It is foreseeable that future container technology will become the basic supporting technology for astronomical and massive data processing.