论文标题
通过Onsala Twin望远镜对无线电源监测无线电的宽带通量密度
Broad band flux-density monitoring of radio sources with the Onsala twin telescopes
论文作者
论文摘要
上下文和目的：Onsala双望远镜（OTT）是位于瑞典Onsala太空天文台的两个13 M望远镜。对于双线性极化宽带（3-14 GHz）接收器，它们是下一代非常长的基线干涉法（VLBI）全局观察系统（VGOS）的一部分，用于地理和天文标准。除了纯粹的大地数据产品外，VGO还将定期生成数百个无线电源的全偏图像。这些丰富的监视数据对于天文学和地理位置都很有价值。在这项试点研究中，我们旨在监视10个明亮的无线电来源以寻找耀斑或类似活动，并在长（月）和短（小时）时间尺度上验证仪器校准。方法：我们观察并分析了91个短期（<30分钟），跨越了7个月。我们监视了七个潜在可变的无线电源（0059+581、0552+398、1144+402、1156+295、1617+229、3C418，OJ287）和三个参考校准器（3C147、3C286、3C295）。我们使用常见的天文学软件应用程序（CASA）软件包来边缘拟合，频带校正和缩放数据以在四个标准VGOS频段中获得通量密度：3.0-3.5 GHz（频段1），5.2-5.7 GHz（Band 2），6.3-6.8 GHz（3.3-6.8 GHz（band 3）和10.2-10.7 GHz（10.2-10.7 GHz（Band 4）。结果：我们获得了十个无线电来源的同时多频光曲线。在无线电源0059+581中观察到明亮的多频耀斑。 OJ287和1156+295显示出显着的长期变异性。结论：在纠正仪器偏见之后，我们确定经验通量密度不确定性为$ \ sim $ 5％。未来的精制分析方法将允许定期监视更多和淡淡的来源。
Context and aims: The Onsala twin telescopes (OTT) are two 13 m telescopes located at the Onsala Space Observatory in Sweden. With dual linear polarized broad-band (3-14 GHz) receivers, they are part of the next generation Very Long Baseline Interferometry (VLBI) Global Observing System (VGOS) for geodesy and astrometry. In addition to purely geodetic data products, VGOS will regularly produce full-polarisation images of hundreds of radio sources. These rich monitoring data will be valuable for both astronomy and geodesy. In this pilot study we aim to monitor 10 bright radio sources to search for flares or similar activity, and to verify the instrument calibration on long (months) and short (hours) time scales. Method: We observed and analysed 91 short (<30 min) sessions spanning 7 months. We monitored seven potentially variable radio sources (0059+581, 0552+398, 1144+402, 1156+295, 1617+229, 3C418, OJ287) and three reference calibrators (3C147, 3C286, 3C295). We used the Common Astronomy Software Applications (CASA) package to fringe-fit, bandpass-correct and scale the data to obtain flux densities in the four standard VGOS bands: 3.0-3.5 GHz (band 1), 5.2-5.7 GHz (band 2), 6.3-6.8 GHz (band 3), and 10.2-10.7 GHz (band 4). Results: We obtain simultaneous multi-frequency light curves for ten radio sources. A bright multi-frequency flare is observed in the radio source 0059+581. OJ287 and 1156+295 show significant long-term variability. Conclusions: After correcting for instrumental biases, we determine the empirical flux density uncertainty as $\sim$5%. Future refined analysis methods will allow regular monitoring of more and fainter sources.
