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1.
上海天文台１ ．５６ 米反光镜于１９９１ 年引入的Ｔｈｏｍｓｏｎ １０２４ ×１０２４ＣＣＤ 系统,到１９９８ 年３ 月已满７ 年。本文对此ＣＣＤ 系统的某些性能变化做了讨论。 相似文献
2.
散射光对准确CCD平场的影响--修改某些反光镜挡光筒的必要性 总被引：1，自引：0，他引：1
继前文之后，进一步说明，晨昏蒙影平场与夜天露光的差别主要由于存在散射光．像Grundahl和Sorensen那样，上海天文台1．56米和南京大学63厘米反光镜的针孔像也已获得，直观地显示了散射光的存在，1．56米和63厘米反光镜都有标准设计的挡光筒，所有标准设计的反光镜都只有两个挡光筒，分别置于主镜和付镜前面．为了在得出准确平场时CCD不受散射光影响，这样的挡光筒是不够的．这是所有标准设计的档光筒共同的弱点．为了得到更准确的平场改正，修改所有类似的反光镜主镜挡光筒是极其重要的。 相似文献
3.
对兴隆６０ｃｍ望远镜主焦ＣＣＤ系统的测光性能进行了测试和研究．测定了ＣＣＤ快门时间函数,讨论了快门延迟效应对短时间曝光观测的可能影响．通过观测大批Ｌａｎｄｏｌｔ标准星,较准确地定出了ＢＶＲＩ宽带测光的星等系统转换关系,结果表明本系统与标准ＢＶＲＩ系统很接近．对ＣＣＤ系统的天文测光精度作了仔细的检验和分析,并对ＰＳＦ拟合测光和孔径测光两种方法进行了比较 相似文献
4.
给出１９９７年３月９日日全食时所作的日冕偏振ＣＣＤ观测资料的处理结果,包括太阳赤道东西和两极等十二个方向的中冕（１．６－３．２Ｒ）绝对亮度分布和偏振度分布。 相似文献
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给出１９９７年３月９日日全食时所作的日冕偏振ＣＣＤ观测资料的处理结果,包括太阳赤道东西和两极等十二个方向的中冕（１．６￣３．２Ｒ⊙）绝对亮度分布和偏振度分布。 相似文献
6.
对兴隆６０ｃｍ望远镜主焦ＣＣＤ系统的测光性能进行了测试和研究,测定了ＣＣＤ快门时间函数,讨论了快门延迟效应对短时间曝光观测的可能影响,通过观测大批Ｌａｎｄｏｌｔ标准星,较准确地定出了ＢＶＲＩ宽带测光的星等系统转换关系,结果表明本系统与标准ＢＶＲＩ系统很接近,对ＣＣＤ系统的天文测光精度作了仔细的检验和分析,工对ＰＳＦ拟合测光和孔径测光两种方法进行了比较。 相似文献
7.
云南天文台PI1024TKB CCD 总被引：1，自引：0，他引：1
详细介绍了云南天文台１ｍ望远镜新近引进的美国ＰｒｉｎｃｅｔｏｎＩｎｓｔｒｕｍｅｎｔｓ公司ＰＩ１０２４ＴＫＢ ＣＣＤ及其控制器ＳＴ－１３８的各基参数指标和使用方法。 相似文献
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本文推导了低纬子午环采用ＣＣＤ测微器观测时所得测定值的各种星径曲率改正公式。针对云南天文台具体的地理位置（纬度为２５°），在不同观测天顶距情况下，给出了ＣＣＤ视场中不同位置的天体通过参考平面（子午平面或卯酉平面）时，星过记录时刻和天顶距测定值的星径曲率改正模拟运算结果。结果表明：对于偏离ＣＣＤ芯片相对中心的天体，其星径曲率改正值比较大，且随天体偏离距离的增加而增大。 相似文献
10.
１９９６年３月中旬，我们在观测海尔－波普彗星的同时，使用了云南天文台１ｍ镜加新研制的１０２４×１０２４ＣＣＤ照像机，对百武彗星也进行了照像观测。精密定位表明与最新的预报值仍有较大偏离。此时彗发已相当大，基本上轴对称。明显可见在对准太阳的相反方向有尾流物质喷出。但是我们发现，在短时间内，近核部分的尾向角就有变化，说明尾部湍流的波动非常激烈 相似文献
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《中国天文和天体物理学报》2014,(10)
正Research in Astronomy and Astrophysics publishes original research papers and reviews on all branches of astronomy and astrophysics.Reviews are by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length to 6 printed pages).Authors who submit a paper are expected to be able to certify that the paper is original work, 相似文献
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《中国天文和天体物理学报》2014,(9)
正Research in Astronomy and Astrophysics publishes original research papers and reviews 011 all liranchcs of astronoiriy and astrophysics.Reviews arc by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length 相似文献
15.
Laura Schaefer 《Icarus》2005,173(2):454-468
We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10−6 to 10+1 bars) ranges, which overlap the nominal conditions at Pele (T=1760 K, P=0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. The elemental abundances for O, S, Na, K, and Cl are based upon observations. CI chondritic elemental abundances relative to sulfur are used for the other alkalis and halogens (as yet unobserved on Io). We predict the major alkali species in Pele-like volcanic gases and the percentage distribution of each alkali are LiCl (73%), LiF (27%); NaCl (81%), Na (16%), NaF (3%); KCl (91%), K (5%), KF (4%); RbCl (93%), Rb (4%), RbF (3%); CsCl (92%), CsF (6%), Cs (2%). Likewise the major halogen species and the percentage distribution of each halogen are NaF (88%), KF (10%), LiF (2%); NaCl (89%), KCl (11%); NaBr (89%), KBr (10%), Br (1%); NaI (61%), I (30%), KI (9%). We predict the major halogen condensates and their condensation temperatures at P=0.01 bar are NaF (1115 K), LiF (970 K); NaCl (1050 K), KCl (950 K); KBr (750 K), RbBr (730 K), CsBr (645 K); and solid I2 (200 K). We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. Their estimated photochemical lifetimes range from a few minutes for alkali iodides to a few hours for alkali fluorides. Condensation is apparently the only loss process for elemental iodine. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F. 相似文献
16.
Li Xin-nan Zhang Hai-ying Cui Xiang-qun Jiang Zi-bo Zheng Yi Liu Xing-tao Ni Hou-kun 《Chinese Astronomy and Astrophysics》2012
A special stressed annular polishing technique is proposed to mill the off-axis aspheric sub-mirrors of a large segmented mirror with an annular polishing machine. Based on the basic principle of stressed annular polishing technique, a set of special stressing mechanisms are designed to convert milling the aspheric surfaces of sub-mirrors with different off-axis distances into milling the spherical surfaces with identical radii of curvature, so that they can be pol- ished simultaneously on a continuous polishing machine. It took about contin- uous 40 hours to polish a scaled-down mirror of the planning Chinese Future Giant Telescope (CFGT) using this technique. This mirror has the 330 mm di- ameter, 3.6 m off-axis distance, and the 21.6 m radius of curvature, and its max- imum asphericity is 16 micron. The experiment shows that this method has a high effciency, suits batch manufacturing, especially the batch manufacturing of aspheric sub-mirrors of the segmented primary mirror of an extremely large aperture telescope. 相似文献
17.
Yehouda Enzel Rivka Amit Uri Dayan Onn Crouvi Ron Kahana Baruch Ziv David Sharon 《Global and Planetary Change》2008,60(3-4):165-192
Modern-day synoptic-scale eastern Mediterranean climatology provides a useful context to synthesize the diverse late Pleistocene (60–12 ka) paleohydrologic and paleoenvironmental indicators of past climatic conditions in the Levant and the deserts to its south and east. We first critically evaluate, extract, and summarize paleoenvironmental and paleohydrologic records. Then, we propose a framework of eastern Mediterranean atmospheric circulation features interacting with the morphology and location of the southeast Mediterranean coast. Together they strongly control the spatial distribution of rainfall and wind pattern. This cyclone–physiography interaction enforces the observed rainfall patterns by hampering rainfall generation south and southeast of the latitude of the north Sinai coast, currently at 31°15′.The proposed framework explains the much-increased rains in Lebanon and northern Israel and Jordan as deduced from pollen, rise and maintenance of Lake Lisan, and speleothem formation in areas currently arid and semiarid. The proposed framework also accounts for the southward and eastward transition into semiarid, arid, and hyperarid deserts as expressed in thick loess accumulation at the deserts' margins, dune migration from west to east in the Sinai and the western Negev, and the formation of hyperarid (< 80 mm yr− 1) gypsic–salic soils in the southern Negev and Sinai. Our climatic synthesis explains the hyperarid condition in the southern Negev, located only 200–250 km south of the much-increased rains in the north, probably reflecting a steeper rainfall gradient than the present-day gradient from the wetter Levant into its bordering southern and eastern deserts.At present, the rainiest winter seasons in Lebanon and northern and central Israel are associated with more frequent (+ 20%), deeper Cyprus Lows traversing the eastern Mediterranean at approximately the latitude of southern Turkey. Even these wettest years in northern Israel do not yield above average annual rainfall amounts in the hyperarid southern Negev. This region is mainly influenced by the Active Red Sea Troughs that produce only localized rains. The eastern Mediterranean Cyprus Lows also produce more dust storms and transport higher amounts of suspended dust to the loess area than any other atmospheric pattern. Concurrent rainfall and dust are essential to the late Pleistocene formation of the elongated thick loess zone along the desert northern margin. Even with existing dust storms, the lack of rain and very sparse vegetation account for the absence of late Pleistocene loess sequences from the southern Negev and the formation of hyperarid soils.When the north Sinai coast shifted 30–70 km northwest due to last glacial global sea level lowering, the newly exposed coastal areas supplied the sand and dust to these active eastern Mediterranean cyclones. This enforced the latitude of the northern boundary of the loess zone to be directly due east of the LGM shoreline. This shift of coast to the northwest inhibited rainfall in the southern Levant deserts and maintained their hyperaridity. Concurrently, frequent deep eastern Mediterranean Cyprus Lows were funneled along the northern Mediterranean increasing (probably doubling) the rains in central and northern Israel, Lebanon, southwestern Syria and northern Jordan. These storms and rains formed lakes, forests, and speleothems only a short distance north of the deserts in the southern Levant. 相似文献
18.
Philippe Stee 《Astrophysics and Space Science》2003,286(1-2):225-236
Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar
environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better
constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the
importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells.
Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
The central compact object for some gamma-ray bursts (GRBs) may be a strongly magnetized millisecond pulsar. It can inject energy to the outer shock of the GRB by through the magnetic dipole radiation, and therefore causes the shallow decay of the early afterglow. Recently, from a large number of GRB X-ray afterglows observed by Swift/XRT(X-ray telescope), it is revealed that many of them exhibit the shallow decay about 102∼104 s after the burst prompt emission. We have fitted the X-ray afterglow light curves of 11 GRBs by using the energy injection model of a magnetar with the rotation period in the millisecond order of magnitude. The obtained result shows the validity and universality of the magnetar energy injection model in explaining the shallow decay of afterglows, and simultaneously provides some constraints on the magnetic field strength and rotation period of the central magnetar. 相似文献