Two dozens of radio loud active galactic nuclei (AGNs) have been observed with Urumqi 25 m radio telescope in order to search for intra-day variability (IDV). The target sources are blazars (namely flat spectrum radio quasars and BL Lac objects) which are mostly selected from the observing list of RadioAstron AGN monitoring campaigns. The observations were carried out at 4.8 GHz in two sessions of 8–12 February 2014 and 7–9 March respectively. We report the data reduction and the first results of observations. The results show that the majority of the blazars exhibit IDV in 99.9% confidence level, some of them show quite strong IDV. We find the strong IDV of blazar 1357 + 769 for the first time. The IDV at centimeter-wavelength is believed to be predominately caused by the scintillation of blazar emission through the local interstellar medium in a few hundreds parsecs away from Sun. No significant correlation between the IDV strength and either redshift or Galactic latitude is found in our sample. The IDV timescale along with source structure and brightness temperature analysis will be presented in a forthcoming paper.

中文翻译：

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在4.8 GHz频率下的数十个Blazar的日内变异性观察

用乌鲁木齐25 m射电望远镜观测到了数十个射电活跃的银河核（AGN），以寻找日内变化（IDV）。目标源是爆炸物（即平坦频谱无线电类星体和BL Lac对象），这些爆炸物大多是从RadioAstron AGN监视活动的观察清单中选择的。分别在2014年2月8日至12日和3月7日至9日的两个会议中以4.8 GHz进行了观测。我们报告了数据减少和观测的初步结果。结果表明，大多数布拉扎斯病毒以99.9％的置信度显示IDV，其中一些显示出很强的IDV。我们首次发现blazar 1357 + 769的强大IDV。据信，在厘米波长处的IDV主要是由离太阳几百秒以内的当地星际介质中的大爆炸发射闪烁引起的。在我们的样本中，IDV强度与红移或银河纬度之间没有显着相关性。IDV时标以及源结构和亮度温度分析将在即将发表的论文中介绍。