Subjects: Astronomy >> Astrophysical processes submitted time 2022-06-16 Cooperative journals: 《天文研究与技术》
Abstract：清代乾隆安徽《铜陵县志》有1507年（明代正德二年）1月发生了一次中心食（日全食和日环食的统称）的观测记载。本文作者利用现代天文行星历表计算了此次日食的日食带，研究当时的世界时改正数。结合明代嘉靖江西《东乡县志》和清代顺治安徽《望江县志》两处地方志关于此次日食的观测记载，进一步分析了东乡县和望江县对此次日食的可观测情况。本文研究对于地球自转的长期变化研究具有一定的参考价值。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-08-20 Cooperative journals: 《天文研究与技术》
Abstract： 对于殷商甲骨文卜辞中存在的唯一可考的一次日食的记载，作者利用美国航空航天局（NASA）喷气推进实验室（Jet Propulsion Laboratory，JPL）发布的DE422行星历表，解算了记载涉及此乙巳日食的主要参数，给出了日食带在地球上的覆盖范围。进一步确认了此次日食在殷都安阳的可视性，验证了殷卜辞对此次日食预测的准确度。
Subjects: Astronomy >> Astrophysical processes submitted time 2020-10-20 Cooperative journals: 《天文研究与技术》
Abstract：关于仲康日食的记载可能是人类历史上最早的一次日食记录，可惜没有记载日食的发生日期。夏商周断代工程研究认为发生在公元前2043年10月3日、公元前2019年12月6日、公元前1970年11月5日和公元前1961年10月26日的日食都可能是仲康日食的备选者。本文作者利用美国航空航天局（NASA） 喷气推进实验室（JPL）发布的现代天文行星历表，计算了这些仲康日食备选者的日食带分布和夏都斟鄩的见食情况，确认了它们在斟鄩的可视性，结果支持夏商周断代工程给出的备选的仲康日食的可能发生时间，并为仲康日食的深入研究提供一定的参考。
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2018-06-22 Cooperative journals: 《天文研究与技术》
Abstract： 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 helping astronomers to find the suitable method to do their calculation.
Subjects: Astronomy >> Astrophysical processes submitted time 2018-05-15 Cooperative journals: 《天文研究与技术》
Abstract：全球卫星导航系统多系统选星问题能够转化为有约束条件的多目标优化问题求解，可以同时优化几何精度因子（GDOP）和选星数目这两个目标，从而在减少接收机运算量的同时获得良好的定位精度。本文提出了一种基于NSGA-II算法的多目标快速选星方法，该方法利用选星问题的序贯性生成初始种群，改进了约束处理方法，并选取合适的遗传算子和效用函数做出选星决策。通过仿真，证实该选星方法具有良好的可靠性和实时性，且不依赖于卫星的几何位置分布，可适用于有障碍或者遮挡的复杂情况。
Subjects: Astronomy >> Astrophysical processes submitted time 2023-01-17 Cooperative journals: 《天文研究与技术》
Abstract： Chinese ancient celestial phenomenon records are the unique astronomical observation data in the world, which have important scientific value. In recent years, with the rapid development of astronomical observations and theories, there have been many new advances in the research of historical supernovae and solar activity cycle. In contrast, the compilations of ancient celestial phenomenon records are still at the level of the late 1980s, and there are defects in the information utilization, such as inconvenient retrieval, and lack of corresponding analysis, which can hardly satisfy the needs of astronomical research. In this paper, the Chinese Ancient Celestial Phenomenon Catalogue based on document-oriented database, full-text retrieval, grammatical analysis and Web technologies has been designed and implemented. The catalogue realizes the digital storage and retrieval of various scientific and historical information in ancient celestial phenomenon records. Through the construction and development of this basic platform, Chinese ancient celestial phenomenon records will be more accessible to astronomers around the world, and promote the intercross research of collation, verification and utilization of ancient celestial phenomenon records.
Subjects: Astronomy >> Astrophysical processes submitted time 2022-11-22 Cooperative journals: 《天文研究与技术》
Abstract： For the problem of output image overlap caused by signal crosstalk in multi-channel digital cameras, we tracked the crosstalk coefficient using the data from the self-developed four-channel CCD digital camera system, and found a strong correlation between the crosstalk coefficient, the input signal intensity, and the system readout speed. For such system noise crosstalk, we propose a crosstalk image correction method based on calibration and image processing. This method establishes the relationship between the crosstalk proportion coefficient and Digital Number，which can be used to infer the amount of interference in the crosstalk channel and realize the crosstalk image recovery algorithm and the systematic error correction. The test results show that after the image correction, the crosstalk degree is reduced to the level of base white noise, and the image quality is greatly improved. This method has a significant effect on the fixed pattern noise caused by the hardware process defects in the imaging system, and also suppresses the noise-type interference of the system, which can be used as a supplement to the image quality optimization of the general image system in practice.
Subjects: Astronomy >> Astrophysical processes submitted time 2022-11-17 Cooperative journals: 《天文研究与技术》
Abstract： Semi-detached binaries are significant targets for the study of the formation and evolution of interacting binaries. Rapid modeling tool is highly required to derive the parameters with large amount of stars to be observed by many recent time-domain photometric surveys. In this work, based on a neural network, a light curve modeling of semi-detached binaries is proposed, which can derive orbital inclination(incl), relative radius(R/a), the mass ratio(q), and temperature ratio(T2/T1) fast via the observational light curve and known effective temperature of the primary star. The results of Kepler's light curve modeling show that the model can accurately fit the light curves of pulsating eclipsing binaries (the fitting degree can reach more than 0.9). For a target whose relative measurement error, orbital inclination, the amplitude of light curve, and temperature ratio are 0.01, ~90°, 1.84 mag, and 0.6, the measurement errors are 1.251, 0.004, 0.008 and 0.003 for incl, R/a, q, and T2/T1, respectively. In addition, as an application, the proposed model in this work can be deployed on other photometric data by simply replacing the train data, which provides an effective tool to obtain a large number of parameters of semi-detached binaries and fast search for candidates of abnormal binaries.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-04-29 Cooperative journals: 《天文研究与技术》
Abstract： 使用全球导航卫星系统（GNSS）进行电离层总电子密度（TEC）反演时，单站相对于多站观测网是一种灵活简便的方法。基于人工神经网络，本文提出了一种准实时单站电离层TEC反演的方法。在这种方法中，上一个时段的硬件偏差被作为初值并随着观测值调整，同时电离层TEC也被准实时地反演。为了对这种方法进行详细的评估，通过位于中国的单站，四天磁静日的TEC被分别采用提出的方法与经典的最小二乘球谐函数法反演，其中硬件偏差和TEC的参考值通过附近的多站网得到。在另一个测试中，通过位于欧洲的单站，一次电离层暴事件及前后平静日的TEC也被分别通过上述方法反演。在磁静日，估计的硬件偏差在整体上相对于最小二乘球谐函数法更接近于参考值，反演的TEC也更接近于参考值。电离层暴时，两种方法反演的TEC也具有很好的一致性，神经网络法估计的硬件偏差与磁静日的硬件偏差更接近。结果表明，提出的神经网络法相比最小二乘球谐函数法具有较高的精度。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-05-27 Cooperative journals: 《天文研究与技术》
Abstract：本文提出了一种非等高电离层薄壳模型，并基于该模型开发了新的全球定位系统硬件偏差和电离层电子密度解算算法。在本模型中，首先利用国际参考电离层模型提供的电子密度剖面数据进行计算得到薄壳高度，然后一方面利用计算得到的薄壳高度对电离层高度变化规律进行了分析；另一方面用计算得到的薄壳高度代替以往使用的常数电离层壳高度，得到非等高电离层薄壳模型。分别基于等高模型和非等高模型对2014年的日本全球导航系统观测网的硬件偏差和电离层总电子含量进行计算，并对计算结果进行统计分析，发现由不同模型计算得到的硬件偏差的平均标准差相差大约2%；由不同模型反演得到的总电子含量大约相差0.5 TECU；由日本全球导航系统观测网观测数据反演得到的总电子含量和国际参考电离层模型相差可达10 TECU；由非等高模型得到的总电子含量和国际参考电离层模型更加接近。
Subjects: Astronomy >> Astrophysical processes submitted time 2019-03-25 Cooperative journals: 《天文研究与技术》
Abstract：恒星的观测谱一般由连续谱、谱线和噪声组成。其中连续谱是由黑体辐射导致的辐射流量随波长变化的光滑连续光谱。光谱分类以及恒星物理参数估计等研究都依赖于连续谱及谱线信息的准确提取。因此光谱数据处理的主要工作就是拟合连续谱，并通过对光谱进行归一化来 提取谱线特征。目前连续谱拟合的方法主要有多项式拟合、中值滤波、小波滤波等。已有的方法在低信噪比，宇宙线信号干扰，存在发射线等情况下，都有不同程度的局限性，主要体现在鲁棒性和准确度上。目前，对于LAMOST的10 7 条光谱没有自动化方法应用到归一上，在天文数据雪崩的时期，研究并开发一种能够适用于更广的温度、信噪比及波长覆盖范围的，具有更好普适性并能够自动化处理的恒星光谱归一化算法，显得十分迫切。在仔细分析不同类型光谱的基础上，提出了一种基于固定窗口划分的连续谱拟合方法。该方法对光谱中能够体现连续谱特征的数据点进行筛选提取，通过细微地控制样条函数平滑度来产生更加准确的连续谱。使用LAMOST中不同光谱型、温度范围、波长覆盖范围的光谱进行实验，结果表明文章提出的算法具有良好的精度和普适性。
Subjects: Astronomy submitted time 2023-12-13 Cooperative journals: 《天文学进展》
Abstract： This work reviews Tully-Fisher relation and baryonic Tully-Fisher relation(TFR and BTFR), which are important scaling relations connecting galaxy luminosity and baryonic mass with its rotation velocity. TFR and BTFR both serve as the standard rules in comic distance measurements and thus are crucial in determining cosmological parameters. TheTFR make use of photometries in several bands. Despite the scaling relation existing in different wavelength, the slope and scatter varies. This can be explained by the different formation histories of different main tracers, e.g. the mass-to-light ratio is lower at shorter wavelength which is contributed mainly by young stars. Among all bands, the I and R bands present the smallest scatter. In order to further reduce the scatter of TFR, the luminosity is later replaced with stellar mass. Compared to TFR, BTFR includes gas components. It has many advantages. For example, the scatter, especially the intrinsic scatter, of BTFR is even smaller than that of the (stellar mass)TFR. Such tight relation also holds at low-masses. Besides, BTFR is more compatible, as it applies not only to disky galaxies, but also for irregular galaxies. To obtain the rotation velocity of the galaxy gas component, two kinds of telescope are used, telescope arrays and single-dish telescopes. The telescope array is superior to the single-dish in providing high spatial resolution image and velocity field data. With the help of modern theories, such as the tilted-ring model, one could obtain the rotation curve. On the other hand, large single-dish telescopes like FAST have high sensitivities given their large area, which is very useful in detecting weak sources like ultra diffuse galaxies(UDGs). In this paper, we present our preliminary results on the dependence of BTFR of massive galaxies on their gas fraction. We combine ALFALFA survey data with SDSS data, finding evidence of the gas fraction dependence. While BTFR is nearly independent on gas fraction for massive galaxies, at low masses, a weak yet positive dependence on gas fraction presents itself. Further studies using upcoming large arrays like SKA could be able to provide more reliable data for the kinematical studies.
Subjects: Astronomy >> Astrophysical processes submitted time 2020-12-21 Cooperative journals: 《天文研究与技术》
Abstract：殷卜辞中有5次纪日月食记载是目前已知的可为殷商时期天文定年的最确凿的材料，夏商周断代工程研究给出了这5次殷卜辞月食的发生日期。本文作者利用美国航空航天局（NASA）喷气推进实验室（JPL）发布的现代天文行星历表DE422，解算这5次月食的主要参数，研究它们在地球表面的可观测情况，进一步确认这5次月食在殷都安阳的可视性。研究结果支持夏商周断代工程给出的5次月食的发生日期，并可为殷卜辞月食的深入研究提供一定的参考。
Subjects: Astronomy >> Astrophysical processes submitted time 2022-09-19 Cooperative journals: 《天文研究与技术》
Abstract： The observation and study of all kinds of variable stars are important part of time domain astronomy. Xinglong Observatory, NAOC as the largest observatory in the Asia continent. It owns several meter-aperture astronomical telescopes, which are opened to scientists from all countries. There telescopes are observing a lot of variable stars, but a dedicated data reduction pipeline is lacking. This paper introduces an automatic pipeline, which can extract light-curve from raw observation data. This pipeline is highly modularized and customizable, and can be applied to data from different optical astronomical telescopes after minor customization. The structure, the feature, and the usage of this pipeline are discussed in this paper, together with a sample of eclipsing-binary UY UMa. In the end, the limit of this pipeline is listed with future improve planning.
Subjects: Astronomy >> Astrophysical processes submitted time 2020-07-24 Cooperative journals: 《天文研究与技术》
Abstract：随着激光测量技术的不断发展，有着“测量机器人”美誉的全站仪，在测量精度、灵活机动、快速便捷等方面，有着其它测量技术不可比拟的优势。全站仪作为“天眼”中主要的测量设备，在现场室外大尺度环境下，如何克服大气折射的影响，了解全站仪动态测量性能，实现高精密的快速扫描测量和高精度的动态跟踪测量，是其中的关键和难点所在。要克服测量过程中不确定因素影响，需了解其影响程度。本文内容包括介绍研发的“风琴式护罩运动平台”、实验过程和数据分析方法。评价全站仪在现场环境下的测量精度和实时性，通过实验测试得到全站仪的时滞在195-295ms 之间，测量精度约为5.3mm。此结论为后续误差修正提供依据。
Subjects: Astronomy submitted time 2024-07-03 Cooperative journals: 《天文学进展》
Abstract： Cloudiness is one of the important evaluation parameters for the site selection of ground-based photoelectric telescopes in astronomical field. The traditional cloudiness calculation method has a large deviation in the accuracy of cloudiness calculation for all-sky camera imagery, which is difficult to meet the actual demand for the accuracy of cloudiness calculation in multiple fields, and there are some limitations in its detection model extraction capability. Aiming at the problems of daytime cloudiness calculation of all-sky camera imag#2;ing, a deep learning-based daytime cloudiness calculation model of all-sky camera imaging is proposed. In the cloudiness detection layer, the model constructs a Channel Weighting#2;Feature Fusion (CWFF) structure to enhance the cloud memory and deep feature extraction capability to accomplish the cloudiness detection task. In the cloudiness calculation layer, the model proposes a cloudiness calculation method based on the cloudiness detection model, which effectively improves the error rate of cloudiness calculation. Experiments show that the combined accuracy of this paper’s method in the cloudiness detection task exceeds 95%, and the average absolute error in the cloudiness volume calculation task does not exceed 5%.
Subjects: Astronomy >> Astrophysical processes submitted time 2023-12-06 Cooperative journals: 《天文研究与技术》
Abstract： We conducted a test using the popular science telescope, Sky-Watcher 150PDS, and the amateur-grade ZWO ASI120MM-S CMOS camera to explore the feasibility of using popular science equipment for professional astronomical observation and scientific research. Initially, we evaluated the basic performance and parameter curves of the CMOS camera, which met the fundamental requirements for professional astronomical observation. Subsequently, we installed the CMOS camera on the Sky-Watcher telescope and performed basic astronomical observations at the Xinglong Observatory, NAOC. We observed the open cluster M35 and the short-period variable star V∗V2455 Cyg, while acquiring the necessary photometric auxiliary images (bias and flat). The acquired data underwent professional astronomical image processing techniques, including astrometric calibration, aperture photometry, and flux calibration. This allowed us to obtain the photometric data, light curve, and performed a simple period analysis for the observed targets. By comparing our photometric results with known star catalogs, we determined that the photometric precision of our system exceeded 0.02 mag, with a differential photometric precision of approximately 0.005 mag. These results demonstrate the capability of popular science telescopes and CMOS cameras for conducting astronomical observations and research. Consequently, this opens opportunities for primary and secondary school students as well as astronomy enthusiasts to actively participate in astronomical scientific observation and research.
Subjects: Astronomy >> Astrophysical processes submitted time 2021-11-12 Cooperative journals: 《天文研究与技术》
Abstract： 恒星耀发是剧烈的恒星活动过程，对恒星周围的行星上的大气构成和生命演化有重大影响。恒星耀发的辐射主要分布在光学和X射线波段，其中耀发时X射线波段流量可以增大数十倍至数百倍。M型耀星是最有可能存在类地行星的宿主恒星，因此研究M型耀星的X射线耀发分布对寻找宜居的类地行星具有重要意义，并且也可以为即将发射的爱因斯坦探针卫星项目（EP）对恒星耀发的探测数目估计提供参考。我们利用X 射线全天监视器MAXI的巡天监测数据研究了M型耀星AT Mic的 X 射线耀发的统计性质。从 MAXI11年的巡天数据中，通过分析图像、光变曲线和能谱数据和信息，发现 MAXI在 11 年间 一共探测到 10 次信噪比大于 3的耀发，获得了耀发光度的统计分布。在此基础上，我们对恒星耀发的耀发频率进行了估计。
Subjects: Astronomy >> Astrophysical processes submitted time 2021-07-30 Cooperative journals: 《天文研究与技术》
Abstract： GNSS（Global Navigation Satellite System，全球导航卫星系统）接收机在接收到卫星信号后，经过捕获、跟踪，得到码相位与载波相位两个基本的测量值。然后通过测量值计算卫星与接收机之间的距离。载波相位测量值比码相位测量值具有更高的测量精度，但由于载波相位测量值具有计算整周模糊度的问题，在实际的计算当中得到高精度的相位测量结果需要付出更多的计算代价。因此，在实际应用中，得到更高精度的码相位测量结果具有更实际的意义。本文在基于相位条纹的技术基础上，通过提取互相关功率谱，提出一种更高精度的码相位测量方法，得到更高精度的码相位测量值，从而得到更高精度的码伪距测量结果，并通过实际的GNSS的信号验证了本方法的有效性。
Subjects: Astronomy >> Astronomical Instruments and Techniques submitted time 2018-06-22 Cooperative journals: 《天文研究与技术》
Abstract： Withconstructing and completingof global satellite positioning systems such as GPS, GLONASS, Galileo and BDS, using two or more than two signals ofdifferent positioning systems toachieve the combined positioning has become a hotspot in research of navigation.Compared with traditional single system positioning, multi-system combination has stronger environmental adaptability and better performance of determining position, velocity and time.By combined static single point positioning of CAPS, BDS and GPS, we achieve the combined positioning of transponding system with straight forward system, verify the feasibility of CAPS participating in GNSS multi-system positioning, and analyze the positioning performance and accuracy.The analysis shows that CAPS are fully feasible in multi-system positioning, single point positioning accuracy is better than 3 meters and there is room for improvement.The addition of CAPS enriches the selection of GNSS system, and has research significance and application value for improving the diversity of GNSS positioning and the positioning performance.
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