依巴谷星(104297)相对于伽里略卫星Callisto的CCD位置测量

１９９７年１１月１４日晚，在中国科学院云南天文台１米望远镜上用新安装的１０２４２ＣＣＤ观测到了木星的两颗伽里略卫星；Ｅｕｒｏｐａ和Ｃａｌｌｉｓｔｏ及一颗依巴谷星（星号为 １０４２９７）．当采用新的 ＪＰＬ ＤＥ４０５和 Ｓａｍｐｓｏｎ－Ｌｉｅｓｋｅ理论（Ｇ５）计算卫星的理论位置并相对于Ｃａｌｌｉｓｔｏ测量恒星位置时，视位置的观测值与计算值之差的平均值在赤经和赤纬方向分别为△α＝－０″０２９±０．″０１２，△δ＝０．″００５± ０．″０１１．这对应于平均观测历元（ＵＴ）：１９９７年１１月１４日１３时４３分５０秒．这一试验结果与 Ｃａｓａｓ等在同一时期内ＣＣＤ观测的结果有着很好的一致性 它反映了依巴谷星表体现的光学参考系与ＤＥ４０５体现的动力学参考系在观测历元具有较好的一致性．单次位置测定的标准误差在赤经赤纬方向分别为±０．″０５２和０．″０４７．这一精度明显优于 Ｃａｓａｓ等人发表的 Ｃａｌｌｉｓｔｏ的处理精度，并与目前国际上最好的伽里略卫星观测精度相当     

GPS无线电掩星数据处理系统

GPS无线电掩星技术能提供高精度、高分辨率、全球覆盖的地球电离层和中性层大气剖面。它具有全天候、低费用、无系统长期漂移等优点。从1995年4月至1997年3月,首次GPS／MET试验的成功显示了GPS掩星技术对监测全球大气能够发挥重要的作用,从而成为当前空间探测技术的研究热点之一。该文主要叙述了无线电掩星技术的数据处理系统的有关情况,并介绍了美国UCAR的掩星数据处理系统CDAAC的概况,可作为我国开展无线电掩星计划有关工作的借鉴。     

The characteristics of Asian dust events in Northeast Asia during the springtime from 1993 to 2004

The characteristics of Asian dust events that occurred in Northeast Asia during the springtime from 1993 to 2004 are investigated using 3-hourly SYNOP reports (World Meteorological Organization). Occurrences of blowing sand and dust storm are low in 1997 and 1999, but have increased rapidly since 2000. The maximum occurrence was recorded in 2002. Wind velocity of 6.5 m s^− 1 as a threshold wind velocity is not so exactly consistent with the occurrence of blowing sand. However, wind velocity of 14 m s^− 1 as a strong wind causing dust storm had similar tendency to those of dust storm and Dust Storm Index.Source regions of Asian dust are divided into three regions (A: dry arid, B: semi-arid, and C: cultivated), based upon the occurrence of blowing sand and dust storm. Eight meteorological stations are selected in three regions, which have frequent occurrences of blowing sand. Source regions of Asian dust that affect the Korean peninsula are gradually extending eastward. Positive anomalies of NDVI occurred in 1994, 1995, and 1998 when temperature was high and precipitation was heavy. However, the frequent occurrence of the dust phenomena is not always consistent with lots of vegetation, high temperature, and much precipitation in this study.     

The scattered disk as a source of Halley-type comets

We investigate a new dynamical mechanism for producing Halley-type comets from the scattered disk of comets. Levison and Duncan [Levison, H., Duncan, M., 1997. Icarus 127, 13-32] and Duncan and Levison [Duncan, M., Levison, H., 1997. Science 276, 1670-1672] showed that a significant number of objects leave the scattered disk by evolving to semi-major axes greater than 1000 AU. We find that once these objects reach semi-major axes on the order of ¹⁰⁴ AU, a significant fraction immediately have their perihelia driven inward by the galactic tides. Approximately 0.01% of the objects that reach ¹⁰⁴ AU then evolve onto orbits similar to the observed Halley-like comets due to gravitational interactions with the giant planets. The orbital element distribution resulting from this process is statistically consistent with observations. We discuss the implications of this model for the number of objects in the scattered disk in the text. The model predicts a temporal variation in the influx of HTCs with a period of ∼118 Myr. At the peak, the model predicts that there should be roughly 10 times as many HTCs as currently observed (i.e., there should be weak HTC showers). However, the model may inflate the importance of these showers because it does not include the effects of passing stars and giant molecular clouds.     

Galileo系统及其在中国的应用

较详细地介绍了Galileo系统的全面体系结构、频率设计、服务内容及其广泛的应用范围，指出了它与GPS系统相比的优点，并对开发和增强Galileo系统在我国多层次、全方位的应用提出了建议。     

SAGE测光巡天数据处理方法研究

元素丰度与星系演化(Stellar Abundance and Galactic Evolution,SAGE)是自主设计的能够准确计算恒星大气参数以及消光的新测光系统。对北天除银盘外共计约12 000 deg2的天区开展了SAGE系统测光巡天,计划获取约5亿颗恒星的高精度测光数据。单次曝光条件下100σ完备星等uSC～17. 3,vSAGE～16. 8(AB星等),这些为研究银河系提供宝贵的测光资料。介绍了巡天专用的数据处理程序的研究和开发,主要研究了针对单幅图像的快速自动化处理过程,重点介绍数据改正、天体测量校正、测光和流量定标过程,以及数据结果和数据质量检测等。     

The possible response of life zones in China under global climate change

The response of natural vegetation to climate change is of global concern. In this research, an aggregated Holdridge Life Zone System was used to study the possible response of life zones in China under doubled atmospheric CO₂ concentration with the input climatic parameters at 0.5×0.5° resolution of longitude and latitude from NCAR regional climate model 2 (RegCM2) coupled with the CSIRO global climate model. The results indicate that the latitudinal distribution of life zones would become irregular because of the complicated climate change. In particular, new life zones, such as subtropical desert (SD), tropical desert (TDE) and tropical thorn woodland (TTW), would appear. Subtropical evergreen broadleaved forest (SEBF), tropical rainforest and monsoon forest (TRF), SD, TDE and TTW zones would appear in the northeastern China. Cool-temperate mixed coniferous and broadleaved forest (CMC) and warm-temperate deciduous broadleaved forest (WDBF) zones would appear at latitudes 25–35°N. The temperate desert (TD) in the western China would become Tibetan high-cold plateau (THP), SEBF, WDBF and temperate steppe (TS), and a large part of THP would be replaced by TRF, TDE, SEBF, TS and TTW. The relative area (distribution area/total terrestrial area) of CMC, TRF, TDE and TTW zone would increase about 3%, 21%, 3% and 6%, respectively. However, the relative area of SEBF, TS, TD and THP would decrease about 5%, 3%, 19% and 4%, respectively. In all, the relative area of forests (CCF, CMC, WDBF, SEBF, TRF) would increase about 15%, but the relative area of desert (TD, SD, TDE, and TTW) and THP would decrease about 9% and 4%, respectively. Therefore, responses of different life zones in China to climate change would be dramatic, and nationwide corridors should be considered for the conservation of migrating species under climate change.     

The plane of the Edgeworth-Kuiper belt

We examine possible locations for the primordial disk of the Edgeworth-Kuiper Belt (EKB), using several subsets of the known objects as markers of the total mass distribution. Using a secular perturbation theory, we find that the primordial plane of the EKB could have remained thin enough to escape detection only if it is clustered very closely about the invariable plane of the Solar System.     

恒星干涉仪星光方向矫正伺服系统

恒星干涉仪的关键技术之一是用自适应光学技术来调节两相干光束之间的夹角,以保证干涉条纹可见度的损失最小。在我们的恒星干涉仪实验系统中,光束方向矫正系统就是为这一目的而研制的．该系统中的光子计数系统和8098单板机的软、硬件组成了补偿光束方向随大气扰动而变的系统．文章介绍了该伺服系统以及在实验系统联调时的试验结果。