A double-channel photometer for the Swedish ESO submillimeter telescope     

L. Pizzo  P. Andreani  G. Dall'Oglio  R. Lemke  N. Whyborn  A. Otàrola 《Experimental Astronomy》1995,6(3):249-256

A double channel (1.2 and 2 mm) photometer has been installed at the focus of the 15m SEST antenna in Chile to perform measurements of the Sunyaev-Zeldovich effect towards X-ray ROSAT clusters. This paper describes the instrument and the characteristics of the system: its sensitivity, field of view, noise and the performed calibrations.  相似文献   

太阳微波爆发中精细结构的统计研究     

傅其骏  刘玉英 《中国天文和天体物理学报》1996,(2)

本文总结了北京天文台1991年的2840MHz波段微波爆发中精细结构（FS）事件的观测．从FS的时间标度、强度、共生的微波爆发的峰值流量、FS发生在微波爆发的相位和FS与Hα耀斑的关系等方面作了统计分析．发现约67％以上的FS其持续时间为几十毫秒到几百毫秒，85％以上的FS幅度小于200sfu．讨论了FS的时标、强度及22周太阳峰年期与21周FS出现率的差别．  相似文献   

Map-making methods for cosmic microwave background experiments     

XavierDupac  MartinGiard 《Monthly notices of the Royal Astronomical Society》2002,330(3):497-505

The map-making step of cosmic microwave background (CMB) data analysis involves linear inversion problems that cannot be performed by a brute-force approach for the large time-lines of today. In this paper we present optimal vector-only map-making methods, which are an iterative COBE method, a Wiener direct filter and a Wiener iterative method. We apply these methods on diverse simulated data, and we show that they produce very well restored maps, by removing nearly completely the correlated noise that appears as intense stripes on the simply pixel-averaged maps. The COBE iterative method can be applied to any signals, assuming the stationarity of the noise in the time-line. The Wiener methods assume both the stationarity of the noise and the sky, which is the case for CMB-only data. We apply the methods to Galactic signals too, and test them on balloon-borne experiment strategies and on a satellite whole-sky survey.  相似文献   

从微波爆发的精细结构谱估算粒子能量及磁场位形     

黄光力  倪建平  王仁音 《中国天文和天体物理学报》1994,(1)

本文采用荷兰Ｄｗｉｎｇｌｏｏ射电天文台的多通道频谱仪（４－８ＧＨｚ）所观测到的一种典型的精细结构事例（ＴｙｐｅＨａｎｄ）来证实源区存在小尺度磁场结构以及电子的短时标加速过程．进一步根据实测和理论分析估算电子的平均速度大约为光速的十分之一，微磁流管直径大约为６００ｋｍ．以及在短时标（０．１ｓ）加速过程中电子能量密度的演化．由此可见，在射电精细结构的动态频谱中含有极其丰富的物理信息，对太阳耀斑机制的理解具有重要意义．  相似文献   

从微波爆和X射线爆联合估算日冕磁场     

姚金兴  于兴凤 《天文学报》1994,35(3):318-325

本文假定Ｘ射线爆和微波爆有共同的起源，用它们的爆发流量资料联合估算源中的磁场强度Ｂ、离子数密度ｎｉ和视线方向深度Ｌ．以１９８１年４月２７日０８００ＵＴ的由五个峰组成的延伸爆为例进行了计算。计算结果为：从厚靶模型和热模型得到的五个峰的磁场Ｂ分别为１８６５─６５９Ｇ和７７６─２３４Ｇ；而从薄靶模型算得的Ｂ为３５─１５３Ｇ，ｎｉ为１０８─６×１０９／ｃｍ３，最大的Ｌ为３．３×１０９ｃｍ．这个爆发的Ｘ射线主源的高度在光球上１．４×１０４ｋｍ，因此从薄靶模型得到的结果较为合理，这也与五个峰的“微波富有指数”随时增加相一致的。这似乎表明，五个峰的源位于同一冕环中，能量释放从环顶沿着磁力线向色球方向传播。传播的速度可能是离子声速，因为用上述数据得到的最小的阿尔芬速度超过１０４ｋｍ／ｓ。  相似文献   

Cosmological parameter estimation using Very Small Array data out to  ℓ= 1500      

《Monthly notices of the Royal Astronomical Society》2004,353(3):747-759

  相似文献   

AMSU资料监测新疆雪盖范围的初步应用   总被引：4，自引：1，他引：3  

陈爱军  刘玉洁  杜秉玉 《南京气象学院学报》2003,26(6):759-767

分析了沙漠、森林、草原、平原、高原地区以及水体、积雪等主要地表特征在NOAA-16 AMSU(Advanced Microwave Sounding Unit)对地观测最为敏感的23．8、31．4和89．0GHz通道中的光谱特性,提出了利用这3个通道监测中国新疆地区雪盖范围的方法,并得到了2001年10月到2002年3月新疆地区的旬雪盖图。AMSU监测结果与地面观测记录“点对点”的对比验证结果表明：绝大多数时间段的判识准确率在70％以上,雪盖率的变化趋势与地面观测结果也基本一致,从而确认了监测方法的可靠性及AMSU资料用于积雪监测的能力。另外,简单分析了影响AMSU监测精度的因素,并指出了需要解决的几点问题。  相似文献   

Development of techniques for monitoring gas-phase sodium species formed during coal combustion and gasification     

B. L. Chadwick  R. A. Ashman  A. Campisi  G. J. Crofts  P. D. Godfrey  P. G. Griffin  A. L. Ottrey  R. J. S. Morrison 《International Journal of Coal Geology》1996,32(1-4)

The development of techniques suitable for on-line analysis of gas-phase molecular sodium species, resulting from the combustion and gasification of low-rank coals is described. In particular two techniques have been demonstrated, these are: (a) laser-induced photofragment fluorescence and (b) microwave spectroscopy. The photofragment technique can be applied in situ and yields excellent detection limits (<0.1 ppb of NaCl and 1 ppb NaOH) with good discrimination between the two major gas-phase species — NaCl and NaOH. Limitations of this technique include absorption of the ultraviolet (UV) photolysis excitation by other chemical species and particulates. Microwave spectroscopy shows promise in determining the sodium species distribution in the gas-phase. A purpose built analytical instrument (known as MILLIJET HT) is being developed for application in high-temperature environments. Early results indicate detection limits of <100 ppb NaCl. Lack of sensitivity for NaOH is being attributed to the formation of NaOH dimers and larger clusters. Detailed calculations of the dimer structure and the dimer-monomer reaction have been undertaken in order to maximise the performance of the instrument.  相似文献   

微波加热－容量法快速测定萤石中氧化钙     

高岐  张海燕  刘继康 《岩矿测试》1996,(4)

利用微波加热分解试样配位滴定法测定了萤石中氧化钙，与经典沸水浴浸取方法相比较，测定结果符合、精度水平一致，操作简便、测定速度大大提高，适合于大批量样品分析。经Ｆ检验法及ｔ检验法检验，两种方法的分析结果没有明显差异  相似文献   

绿洲、沙漠及戈壁边界层特征对比分析   总被引：4，自引：0，他引：4  

朱平  蒋瑞宾 《气象》1996,22(3):48-50

利用黑河实验所取得的资料，对比分析了绿洲、沙漠及戈壁边界层中风、温、湿分布规律，从而为研究西北地区不同下垫面所造成的气候特点对生态环境的影响、土地的开发腹及人工改造自然环境等工作提供依据。  相似文献