Very Long Baseline Interferometric Research at North LibertyRadio Observatory

甚长基线干涉测量技术（VLBI）用于射电天文学中观测射电源的精细尺度结构。观测是由相隔数千英里的射电望远镜同时进行的。数据被记录在磁带上，并发送到一个单一的位置以减少数据。因此，人们可以观察到角间距为千分之一弧秒的结构。这比用物理连接或单个望远镜观测要好上百倍。同样的技术也可以用来测量地球上的地壳运动。VLBI观测对于我们理解诸如类星体等射电源中发生的物理过程非常重要。首席研究员将使用VLBI技术进行射电天文观测。作为美国VLBI网络的一部分，北自由无线电天文台（NLRO）的继续运作得到了支持。NLRO是美国六个机构中的一个，是美国网络的正式成员。NLRO是5 GHz及以下频率VLBI观测（使用MkII）记录的重要参与者。在过去的两年中，NLRO被使用了1200多个小时，进行了62次单独的实验。随着全球条纹拟合和自校准技术（最适合大量望远镜）的使用越来越普遍，NLRO在网络VLBI实验中的应用正在稳步增加。该阵列的“爱荷华”部分将在未来两年内完工，并将取代目前的望远镜。该奖项将支持Mutel博士的VLBI研究。将对射电源BL Lacertae中的结构进行观测，其部分似乎正在以超过光速的速度膨胀。其他观测将对选定的紧凑双射电源进行。将搜索一个中心组件。某些双星的射电辐射将被观测以寻找相干射电暴。将研究银河平面附近致密射电源的星际散射。Mutel博士是一位有能力和经验丰富的射电天文学家，他的研究结果将对我们了解射电源非常重要。

The technique of Very Long Baseline Interferometry (VLBI) is used in radio astronomy to observe fine-scale structure in radio sources. Observations are made simultaneously from radio telescopes separated by thousands of miles. The data is recorded on magnetic tapes and sent to a single location to reduce the data. One can thus observe structures one-thousandth of a second of arc in angular separation. This is more than a hundred times better than one can observe with physically connected or single telescopes. The same techniques can be used to measure crustal motions on the Earth. The VLBI observations are important to our understanding of the physical processes taking place in radio sources such as quasars. The Principal Investigator will carry out radio astronomical observations using VLBI techniques. There is support of continued operation of the North Liberty Radio Observatory (NLRO) as part of the U.S. VLBI Network. The NLRO is 1 of 6 institutions in the U.S. which are full members of the U.S. Network. The NLRO is an important participant in VLBI observations (using MkII) recording at frequencies of 5 GHz and below. The NLRO was used for more than 1200 hours for 62 separate experiments during the last 2 years. The use of NLRO for Network VLBI experiments is steadily increasing as the use of global fringe fitting and self calibration techniques (which work best with a large number of telescopes) become more common. The "Iowa" element of the Array should be completed in the next 2 years and will supplant the present telescope. This award will support Dr. Mutel's VLBI research. Observations will be made of structures in the radio source BL Lacertae, whose parts seem to be expanding at speeds exceeding the speed of light. Other observations will be made of selected compact double radio sources. A search will be made for a central component. Radio emissions from certain binary stars will be observed to look for coherent radio bursts. Interstellar scattering of compact radio sources near the galactic plane will be studied. Dr. Mutel is a competent and well-experienced radio astronomer and the results of his research will be important to our understanding of radio sources.