黄海、东海区域漫衰减系数光谱遥感反演及激光测深性能评估     

李凯  童晓冲  张永生  哈长亮  申二华 《遥感学报》2015,19(5):761-769

本文在总结和比较中国现有黄海、东海海域漫衰减系数反演算法的基础上,利用水色测量数据分析得到漫衰减系数Kd(532)与Kd(490)之间的关系,为激光测深系统(以CZMIL为例)的性能评估提供了基础。利用MODIS二级数据产品评估了中国黄海、东海海域在CZMIL海道测量模式下最大可测水深的空间分布。研究结果表明CZMIL在黄海、东海海域可测水深基本在0—50 m,该区域的面积占研究区域面积的比例为76.2%,为浅海海域开展激光测深作业提供了测深能力评估的依据和方法。  相似文献   

加速迭代硬阈值ISAR稀疏成像     

雷大力  洪峻  王宇  费春娇 《遥感学报》2015,19(5):770-779

加速迭代硬阈值(AIHT)作为一种压缩感知(CS)算法,具有计算复杂度低、内存占用小的特点,在较小数目的观测下,经过有限次迭代便能获得较好的重建效果。因此,本文将该算法应用到逆合成孔径雷达(ISAR)稀疏成像,对该方法的具体特征和适用性进行了详细分析。仿真结果表明,在相同信噪比和回波脉冲数条件下,基于AIHT的ISAR成像方法,相比于稀疏贝叶斯算法(SBL),在重建时间上缩短了至少2个量级;相比于迭代加权最小二乘法(IRLS)和平滑l0范数算法,在重建质量上提高了约3倍。经实测数据处理结果验证,在1/4原始脉冲数条件下,该方法仍具有良好的聚焦性能和压低旁瓣效果。  相似文献   

一种基于实践九号卫星的快速系统误差补偿技术     

雷蓉  李禄  邓磊  李奇峻 《测绘科学技术学报》2015,32(2):152-156

直接利用光学遥感卫星的严格成像模型对地面点进行定位,定位误差与卫星姿态测量误差有关,其中包括地球自转引起的偏流角误差和姿态角常差。偏流角误差可以根据星历数据予以有效消除,而姿态角常差一般要利用少量控制点进行消除。基于此,在消除偏流角的影响下,这里采用了一种改进的四元数算法——P-H算法用于快速计算姿态角常差,并对系统误差进行补偿。该技术较常用的欧拉角解算,具有原理简单,计算速度快和结果稳定的特点。通过实践九号卫星影像的实验表明,运用该技术能快速和大幅度提高卫星在稀少控制点情况下的定位精度。  相似文献   

Sharp images of young stellar objects     

N. Ageorges  A. Eckart  R. Hofmann 《Astrophysics and Space Science》1995,224(1-2):411-414

We present high resolution infrared images of the pre-main sequence star V536 Aql and polarization maps of the reflection nebula IRN Cha observed with the SHARP camera on the ESO NTT. Extended structures are observed near V536 Aql. The polarization pattern of IRN Cha is typical of a centrally illuminated source but with a central band of anomalously oriented polarization believed to occur in an optically thick disk.  相似文献   

Spot patterns and differential rotation in the eclipsing pre-cataclysmic variable binary, V471 Tau     

G. A. J. Hussain  C. Allende Prieto  S. H. Saar  M. Still 《Monthly notices of the Royal Astronomical Society》2006,367(4):1699-1708

We present surface spot maps of the K2V primary star in the pre-cataclysmic variable binary system, V471 Tau. The spot maps show the presence of large high-latitude spots located at the sub-white dwarf longitude region. By tracking the relative movement of spot groups over the course of four nights (eight rotation cycles), we measure the surface differential rotation rate of the system. Our results reveal that the star is rotating rigidly with a surface shear rate,  dΩ= 1.6 ± 6 mrad d⁻¹  . The single active star AB Dor has a similar spectral type, rotation period and activity level as the K star in V471 Tau, but displays much stronger surface shear  (46 < dΩ < 58 mrad d⁻¹)  . Our results suggest that tidal locking may inhibit differential rotation; this reduced shear, however, does not affect the overall magnetic activity levels in active K dwarfs.  相似文献   

An acousto-optical imaging spectrophotometer for astrophysical observations     

V. Ya. Molchanov  V. M. Lyuty  V. F. Esipov  S. P. Anikin  O. Yu. Makarov  N. P. Solodovnikov 《Astronomy Letters》2002,28(10):713-720

We present the results of our tests of an acousto-optical imaging spectrophotometer with a CCD detector for astronomical observations. The tunable acousto-optical filter, based on a paratellurite single crystal with a 13 Å pass band operates in the wavelength range 6300–11000 Å. We obtained image spectra for the planetary nebula NGC 7027 in the Hα line and for Saturn in the methane absorption band, as well as Hα and continuum images for the nuclear region of the Seyfert galaxy NGC 1068.  相似文献   

恒星形成区GGD12-15的近红外观测     

房敏  姚永强 《天文学报》2004,45(1):1-15

给出恒星形成区GGD12-15的宽波段JHK和窄波段H2v=1-0S(1)近红外成像观测．观测图像揭示了致密的年轻红外星团和与红外源成协的红外星云，并发现了以H2发射结表征的星团外流活动．大多数红外点源在光学波段不可见；对76颗红外点源的JHK′测光结果显示，有32颗具有红外超，其中5颗表现原恒星特征，表明分子云中的恒星形成活动很活跃．以B8光谱型作为大质量星分界，由色星等图估计出大质量星所占星团比例为-10％～26％．GGD12—15星团的K′星等分布的峰值位于15.0mag，并在13．0mag-16．0mag平坦分布；[H—K′]色分布的峰值出现在-0．7mag，在此以上更红的星团成分占70％．在GGD12-15区新发现的氢分子发射结集中在星团中心领域，其空间分布明显与剧烈的恒星形成活动相关；有5个发射结位于分子外流的中心区域，暗示其激发可能与分子外流同源．  相似文献   

Gaseous Jets in Comet Hale-Bopp (1995 O1)     

Lederer  Susan M.  Campins  Humberto  Osip  David J.  Schleicher  David G. 《Earth, Moon, and Planets》1997,78(1-3):131-136

We report the identification of gas jets in comet Hale-Bopp in OH, NH, CN, C₂ and C₃. This is the first time OH and NH jets without an obvious optical dust jet counterpart have been identified in narrowband comet images. We also confirm the existence of CN jets as reported by Larson et al. (1997) and Mueller et al. (1998). Jet features can be seen in the March and April 1997 datasets, approximately a month before and after perihelion. Our results contribute to the understanding of both the chemical properties of the comet as well as the physical mechanisms necessary to produce these features. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

Tomographic Reconstruction of 2-D Vector Fields: Application to Flow Imaging     

Stephen J. Norton 《Geophysical Journal International》1989,97(1):161-168

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PRIMA for the VLTI – Science     

F. Delplancke  F. Derie  F. Paresce  A. Glindemann  F. Lévy  S. Lévêque  S. Ménardi 《Astrophysics and Space Science》2003,286(1-2):99-104

The four main scientific objectives of PRIMA – the Phase-Referenced Imaging and Micro-arc second Astrometry facility for the VLTI – will be described:– extra-solar system characterization with astrometry, to detect planets and evaluate their mass, and imaging of the dust accretion disk,– galactic center study with astrometry(dynamics of the bulge stars) and imaging at 10μm (piercing the gas and dust clouds surrounding the galactic center),– observations of AGNs and other extra-galactic objects, too faint to be observed without PRIMA, for which partial imaging is needed to constrain their structuremodels,– micro-gravitational lensing event resolution (imaging and astrometry of their photo-center) in the Galactic Bulge and Magellanic Clouds, helping to determine directly the lens mass and distance. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献