Multifrequency Polarization Variations in the Quasar 0917＋624

We present a detailed analysis of multi-frequency observations of linear polarization in the intraday variable quasar 0917+624 (z = 1.44). The observations were made in May 1989 at five frequencies (1.4, 2.7, 5.0, 8.3 and 15GHz) with the VLA and the Effelsberg 100 m-telescope and in December 1988 at two frequencies (2.7 and 5.0 GHz) with the latter. It is shown that the relationship between the variations of the polarized and total flux density is highly wavelength dependent, and the multi-frequency polarization behavior may be essential for investigating the mechanisms causing these variations. It is shown that the variations observed at 20 cm can be interpreted in terms of refractive interstellar scintillation. However, after subtracting the variation due to scintillation, three 'features' emerged in the light-curve of the polarized flux density, indicating an additional variable component. Interestingly, these features are shown to be correlated with the variations at 2-6 cm, thus indicating that thes     

密云综合孔径射电望远镜的干扰抑制(英文)

MSRT(密云综合孔径望远镜)从1985年起投入工作。在多年的观测中经常发现来自外部的强大干扰,严重影响着成图的质量。为了抑制观测过程中出现的各类干扰,我们发展了两种软件技术——剔除法和频域滤波法。滤波法的优点在于保留了全部观测信息,适合于长时间强干扰的情形。剔除法对脉冲形的干扰更为敏感有效。这两种技术的配合使用能有效、灵活地抑制各种不同干扰的影响。     

由彗木碰撞引起的十米波爆发

据中国科学院北京天文台与电子工业部２２所的联合观测，证认出１９９４年７月２１日的木星十米波爆发中，有一个爆发可能是由于彗星木星碰撞引起的。     

太阳和月球射电辐射对40m天线数据接收影响分析

利用标准射电源和标准噪声源,对宁静太阳和月球射电辐射的噪声温度进行了测量,估计它们对40m天线接收绕月卫星信号的影响,结论是:(1)40m天线指向偏离太阳超过2°时,能够满足正常数据接收要求;(2)40m天线指向月球时,系统接收的噪声温度增加值为87.1K, 此时系统的总噪声温度能够满足正常数据接收要求.     

由彗木碰撞引起的十米波爆发

据中国科学院北京天文台与电子工业部２２所的联合观测，证认出１９９４年７月２１日的木星十米波爆发中，有一个爆发可能是由于彗星木星碰撞引起的。     

BLO0716＋71非热辐射的喷流模型：从射电到γ射线

本文探讨用相对论喷流模型解释ＢＬ Ｌａｃ天体０７１６＋７１从射电到γ射线的整修电磁波段的非热辐射。喷流的结构分两个区域描述：内区具有抛物线结构，喷流是加速的；外区具有圆锥形结构，喷流速度恒定。相对论电子的密度和最高能量，以及磁场等参数随距离向外按幂律下降。在此模型中，射电至紫外线起源于相对论电子的同步辐射，而高能的Ｘ射线和γ射线则起源于自康普顿散射。辐射的频率越高，产生区域越靠近中央能源机器。辐射     

密云232MHz星表的可靠性研究(英文)

利用密云综合孔径射电望远镜，在232MHZ频率，对于北纬30°以上天区的巡天已经完成.除了银道面区域（|b|＜10°）的射电源外，密云总星表（MGC）共包含了26957颗射电源．MGC的完整性和均匀性已在另文讨论．本文将利用所有处理完的MSRT资料和其它已发表的主要射电源表，研究密云总星表的可靠性．     

A new three-stage evolution model for millimeter to centimeter wavelength outbursts in BL Lacertae

The multi-frequency light curves of BL Lacertae during 1997.5 – 1999.5 have been modeled by four outbursts,each having a 3-stage evolution in the (S m,νm) plane with distinct rising–plateau–decaying phases.It is shown that the observed light curves can be well fitted for the eight frequencies from 350GHz to 4.8GHz.The main characteristics of the model-fitting are: (1) the outbursts are found to have very flat spectra with an optically thin spectral index α (defined as Sν∝ν-α) of about 0.15.This is consisten...     

Refractive Focusing of Interstellar Clouds and Intraday Polarization Angle Swings

Intraday variations of compact extragalactic radio sources in flux density and po- larization are generally interpreted in terms of refractive scintillation from the continuous interstellar medium of our Galaxy. However, continuous polarization angle swings of～180° (for example, the one observed in the QSO 0917 624) could not be interpreted in this way. Qian et al. have shown that the polarization angle swing observed in the QSO 1150 812 can be explained in terms of focusing-defocusing effect by an interstellar cloud, which occults two closely-placed polarized components. Here we further show that the polarization angle swing event observed in the QSO 0917 624 can also be explained in this way. We also found evidence for the cloud eclipsing a non-polarized (core) component during a short period out- side the swing. A particular (and specific) plasma-lens model is proposed to model-fit the polarization swing event of 0917 624. Some physical parameters related to the plasma-lens and the source components are estimated. The brightness temperatures of the two lensed components are estimated to be ～1.6×1013 K. Thus bulk relativistic motion with a Lorentz factor less than ～20 may be sufficient to avoid the inverse - Compton catastrophe.     

3C345中视超光速节点运动轨道的数学描述

本文提出一种数学方法来描述类星体３Ｃ３４５中视超光速节点的运动轨道、它既可以描述内部节点的螺旋运动,又可以描述外部节点的直线运动这种统一的描述方法可能对描述其它致密射电源（例如ＰＫＳ０５２８＋１３４）中视超光速节点的运动是有用的。并有助于研究节点流量的内禀变化。