Quasi-simultaneous five-frequency VLBA observations of PKS 0528+134

¹ Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, PR China e-mail: hbcai@shao.ac.cn
² Graduate School of Chinese Academy of Sciences, Beijing 100039, PR China
³ Joint Institute for Galaxy and Cosmology, SHAO and USTC, PR China

Received: 27 February 2006
Accepted: 28 July 2006

Abstract

We present results of Very Long Baseline Array (VLBA) observations of PKS 0528+134 at five frequencies (2.3, 5.0, 8.4, 15.4, and 22.2 GHz). These quasi-simultaneous data enable us to study the spectral distribution of Very Long Baseline Interferometer (VLBI) components for the first time in this highly variable source, from which the central compact core is identified. Our observations indicate that there are two bendings for the jet motion at parsec scale. We provide an approximate spatial fit to the curved jet trajectory using the Steffen et al. (1995) helical model. We further investigate the proper motions of three jet components, which all show superluminal motion. At high frequencies (15.4 and 22.2 GHz) we detected a new component, which is estimated to be related to a radio burst peaking at about 2000.