Multifrequency VLBA study of the blazar S5 0716+714 during the active state in 2004 II. Large-scale jet kinematics and the comparison of the different methods of VLBI data imaging as applied to kinematic studies of AGN
Elizaveta A. Rastorgueva, Kaj J. Wiik, Anisa T. Bajkova, Esko Valtaoja, Leo O. Takalo, Yliya N. Vetukhnovskaya, Mehreen Mahmud
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13 pages, 7 figures. Accepted for publication in A&A, 2011
We study the jet kinematics of the blazar S5 0716+714 during its active state in 2003-2004 with multi-epoch VLBI observations. Aims. We present a kinematic analysis of the large-scale (0-12 mas) jet of 0716+714, based on the results of six epochs of VLBA monitoring at 5 GHz. Additionally, we compare kinematic results obtained with two imaging methods based on different deconvolution algorithms. The blazar 0716+714 has a diffuse large-scale jet and a very faint bright compact core. Experiments with simulated data showed that the conventional data reduction procedure based on the CLEAN deconvolution algorithm does not perform well in restoring this type of structure. This might be the reason why previous kinematic studies of this source yielded ambiguous results. In order to obtain accurate kinematics of this source, we independently applied two imaging techniques to the raw data: the conventional method, based on difference mapping, which uses CLEAN deconvolution, and the generalized maximum entropy method (GMEM) realized in the VLBImager package developed at the Pulkovo Observatory in Russia. The results of both methods give us a consistent kinematic scenario: the large-scale jet of 0716+714 is diffuse and stationary. Differences between the inner (0-1 mas) and outer (1-12 mas) regions of the jet in brightness and velocity of the components could be explained by the bending of the jet, which causes the angle between the jet direction and the line of sight to change from ~5 deg to ~11 deg. For the source 0716+714 both methods worked at the limit of their capability.
Parsec structure and properties of the jet of 3C273. Results of Space VLBI data processing
本文介绍了W068地空VLBI实验的数据处理结果。特别地，成功地处理了该观测会话的一部分数据。这些数据是在2000年3月17日9：00 UT和10：30 UT之间获得的。本次实验采用了美国甚长基线干涉仪VLBA（Very Long Baseline Array）和日本VLBI空间观测计划VSOP（Space Observatory Programme）的10个天线。此外，27个VLA（甚大阵）天线用作附加的地面天线。数据从NRAO（美国国家射电天文台）的档案中转移，并使用名为“Astro Space Space”（ASL for Windows）的软件进行处理。这一处理的主要结果是标题为3C273的类星体的高分辨率和高精度图像。利用这幅图像，我们对该天体喷流的射电结构作出了一些结论。我们的结果与许多作者早先发表的3C273空间VLBI数据处理的结果并不矛盾。我们可以在结果中添加一些新的方面。给出了3C273在6厘米波段的再现像和该光源的一些参数值。
