利用Karl G. Jansky超大型阵列在紧凑的混合配置
A deep / wide 1-2 GHz snapshot survey of SDSS Stripe 82 using the Karl G. Jansky Very Large Array in a compact hybrid configuration
摘要：
我们使用了卡尔G。Jansky超大阵列成像~100平方米°的SDSS Stripe 82在1-2 GHz下的频率。该调查由1,026个快照观测组成，持续时间为2.5分钟，使用混合CnB配置。该调查对漫射、低表面亮度结构和扩展的无线电发射具有良好的灵敏度，使其与该地区现有的1.4 GHz无线电观测高度协同。主要的数据产品是分辨率为16 x 10弧秒的连续图像，以及一个包含11，782个点和高斯分量的目录，这些分量是根据阈值化的斯托克斯-I亮度分布拟合而成的，形成了大约8，948个独特的射电源。典型的有效1σ噪声水平为88 μJy /束。包括频谱指数估计，从1 GHz的瞬时带宽。天体测量和测光精度与现有的窄带观测非常一致。一个大规模的模拟是用来调查干净的偏见，我们扩展到频谱域。干净的偏见仍然是一个问题，快照调查与VLA，影响我们的总强度测量在~1σ水平。统计光谱指数的测量结果与现有的测量结果吻合良好，这些测量结果来自两个频率的匹配单独调查。在低于~35σ的通量密度下，带内光谱指数测量的中值开始表现出对平坦度的偏差，该偏差取决于通量密度和本征光谱指数。带内光谱曲率的测量可能是不可靠的所有，但非常明亮的组件。图像产品和目录通过FTP服务器公开提供。
英文摘要：
We have used the Karl G. Jansky Very Large Array to image ~100 sq. deg. of SDSS Stripe 82 at 1-2 GHz. The survey consists of 1,026 snapshot observations of 2.5 minutes duration, using the hybrid CnB configuration. The survey has good sensitivity to diffuse, low surface brightness structures and extended radio emission, making it highly synergistic with existing 1.4 GHz radio observations of the region. The principal data products are continuum images, with 16 x 10 arcsecond resolution, and a catalogue containing 11,782 point and Gaussian components resulting from fits to the thresholded Stokes-I brightness distribution, forming approximately 8,948 unique radio sources. The typical effective 1σ noise level is 88 μJy / beam. Spectral index estimates are included, as derived from the 1 GHz of instantaneous bandwidth. Astrometric and photometric accuracy are in excellent agreement with existing narrowband observations. A large-scale simulation is used to investigate clean bias, which we extend into the spectral domain. Clean bias remains an issue for snapshot surveys with the VLA, affecting our total intensity measurements at the ~1σ level. Statistical spectral index measurements are in good agreement with existing measurements derived from matching separate surveys at two frequencies. At flux densities below ~35σ the median in-band spectral index measurements begin to exhibit a bias towards flatness that is dependent on both flux density and the intrinsic spectral index. In-band spectral curvature measurements are likely to be unreliable for all but the very brightest components. Image products and catalogues are publicly available via an FTP server.
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