The investigation of powerful solar flares characteristics by analysis of excited states of C and various neutrons capture lines

Accelerated energetic particles in solar flares produced nuclear γ-lines in interactions with ambient solar atmosphere. Analysis of intensity of ratios between various γ-lines allows us to make estimations of abundance of elements, parameters of surrounding media and other solar characteristics. In this article we discuss the flux ratio between two lines from excited states of ¹²C (f_15.11/f_4.44) and our results of preliminary calculation of intensity ratio between two neutron capture lines at ³He and ¹H (f_20.58/f_2.223). In particular we consider the opportunity to obtain n(³He)/n(¹H) ratio during solar flares and using high-energy gamma-emission studying, based on the satellite data. Possible interpretation of spectral features observed during the January 20, 2005 solar flare is discussed. Preliminary analysis of energy spectrum in the band of 2–21 MeV gives n(³He)/n(¹H) ∼ 8 × 10⁻⁴ for January 20, 2005 solar flare.     

高动态EMCCD星敏感器总体参数设计方法

从高动态星敏感器动态性能需求出发,分析了电子倍增型电荷耦合器件（EMCCD,electron multiplying CCD）噪声来源,推导恒星探测中EMCCD的信噪比公式.针对EMCCD总体参数设计优化问题,提出了EMCCD中电子倍增电压和致冷温度的设计方法,并应用该方法进行高动态星敏感器中EMCCD总体参数设计及仿真.仿真结果表明,角速度为10（°）/s时姿态测量精度优于30″.提出的EMCCD参数确定方法可以为高动态星敏感器设计提供参考.     

IDENTIFICATION OF GYRO DRIFTS UNDER THREE AXIS ATTITUDE COUPLING

ＩＤＥＮＴＩＦＩＣＡＴＩＯＮＯＦＧＹＲＯＤＲＩＦＴＳＵＮＤＥＲＴＨＲＥＥＡＸＩＳＡＴＴＩＴＵＤＥＣＯＵＰＬＩＮＧＪＩＮＧＷｕｘｉｎｇ（荆武兴），ＷＡＮＧＸｕｅｘｉａｏ（王学孝），ＷＵＹａｏｈｕａ（吴瑶华）（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴｅｃｈｎ...     

基于恒星敏感器的仪器星等修正方法

基于恒星敏感器的仪器星等修正方法主要包括星际消光计算（大气层外）与大气消光计算（大气层内）两部分。通过对SKY2000原始星表的恒星星等进行转换计算,修正后星等差一般为0.5星等左右,且与观测仪器的光谱响应有关。     

Applications and usage of the real-time Neutron Monitor Database

A high-time resolution Neutron Monitor Database (NMDB) has started to be realized in the frame of the Seventh Framework Programme of the European Commission. This database will include cosmic ray data from at least 18 neutron monitors distributed around the world and operated in real-time. The implementation of the NMDB will provide the opportunity for several research applications most of which will be realized in real-time mode. An important one will be the establishment of an Alert signal when dangerous solar cosmic ray particles are heading to the Earth, resulting into ground level enhancements effects registered by neutron monitors. Furthermore, on the basis of these events analysis, the mapping of all ground level enhancement features in near real-time mode will provide an overall picture of these phenomena and will be used as an input for the calculation of the ionization of the atmosphere. The latter will be useful together with other contributions to radiation dose calculations within the atmosphere at several altitudes and will reveal the absorbed doses during flights. Moreover, special algorithms for anisotropy and pitch angle distribution of solar cosmic rays, which have been developed over the years, will also be set online offering the advantage to give information about the conditions of the interplanetary space. All of the applications will serve the needs of the modern world which relies at space environment and will use the extensive network of neutron monitors as a multi-directional spectrographic detector. On top of which, the decreases of the cosmic ray intensity – known as Forbush decreases – will also be analyzed and a number of important parameters such as galactic cosmic ray anisotropy will be made available to the users of NMDB. A part of the NMDB project is also dedicated to the creation of a public outreach website with the scope to inform about cosmic rays and their possible effects on humans, technological systems and space-terrestrial environment. Therefore, NMDB will also stand as an informative gate on space research through neutron monitor’s data usage.     

Blue and red supergiants and the age structure of the NGC 330 region

We analysed new UBVRI CCD photometry of the massive, blue SMC cluster NGC 330 and its surrounding field. The age structure and a new reddening value for the stellar population in this region of the SMC are derived and the implications for star formation in this part of the SMC and for stellar evolution are discussed.Based on observations obtained at ESO, La Silla     

顾及星像点分布的恒星相机在轨检校

由于卫星发射前后以及在轨运行过程中,环境因素的变化都可能引起恒星相机参数发生改变,从而导致星敏感器姿态测量精度下降.将多片空间后方交会方法应用于恒星相机的在轨检校.在利用该方法检校时,实验发现检校结果的精度受到参与检校的恒星影像上星像点分布的影响,由此进一步提出了凸包面积百分比准则,该方法自动选取分布较好的影像用于检校,有助于提高检校精度.实验结果证明:基于后方交会进行恒星相机在轨检校时,利用凸包法选取的影像片进行检校的精度明显优于未选片时检校的结果.      

基于星敏感器的卫星角速度估计精度分析

重点研究星敏感器自身特性对角速度估计精度的影响,分析了星敏感器动态情况下恒星矢量测量精度,推导出恒星矢量测量误差与星像目标中心提取误差之间的关系;进而研究了最小二乘角速度估计算法的精度,得出其精度影响因素:星像目标中心提取误差、曝光时间、恒星矢量数目及相互夹角;最后以给定的星敏感器参数和实际恒星分布进行数学仿真,验证了采用星敏感器估计角速度的可行性.     

Low-frequency Periodic Error Identification and Compensation for Star Tracker Attitude Measurement

The low-frequency periodic error of star tracker is one of the most critical problems for high-accuracy satellite attitude determination.In this paper an approach is proposed to identify and compensate the low-frequency periodic error for star tracker in attitude measurement.The analytical expression between the estimated gyro drift and the low-frequency periodic error of star tracker is derived firstly.And then the low-frequency periodic error,which can be expressed by Fourier series,is identified by the frequency spectrum of the estimated gyro drift according to the solution of the first step.Furthermore,the compensated model of the low-frequency periodic error is established based on the identified parameters to improve the attitude determination accuracy.Finally,promising simulated experimental results demonstrate the validity and effectiveness of the proposed method.The periodic error for attitude determination is eliminated basically and the estimation precision is improved greatly.