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SECOND EPOCH VLBA CALIBRATOR SURVEY OBSERVATIONS: VCS-II
The Astronomical Journal ( IF 5.3 ) Pub Date : 2016-05-27 , DOI: 10.3847/0004-6256/151/6/154
David Gordon 1 , Christopher Jacobs 2 , Anthony Beasley 3 , Alison Peck 3 , Ralph Gaume 4 , Patrick Charlot 5 , Alan Fey 4 , Chopo Ma 6 , Oleg Titov 7 , David Boboltz 8
Affiliation  

Six very successful VLBA calibrator survey campaigns were run between 1994 and 2007 to build up a large list of compact radio sources with positions precise enough for use as VLBI phase reference calibrators. We report on the results of a second epoch VLBA Calibrator Survey campaign (VCS-II) in which 2400 VCS sources were re-observed at X and S bands in order to improve the upcoming third realization of the International Celestial Reference Frame (ICRF3) as well as to improve their usefulness as VLBI phase reference calibrators. In this survey, some 2062 previously detected sources and 324 previously undetected sources were detected and revised positions are presented. Average position uncertainties for the re-observed sources were reduced from 1.14 and 1.98 mas to 0.24 and 0.41 mas in RA and Declination, respectively, or by nearly a factor of 5. Minimum detected flux values were approximately 15 and 28 mJy in X and S bands, respectively, and median total fluxes are approximately 230 and 280 mJy. The vast majority of these sources are flat-spectrum sources, with ~82% having spectral indices greater than -0.5.

中文翻译:

第二个时代 VLBA 校准器调查观察:VCS-II

1994 年至 2007 年期间,进行了六次非常成功的 VLBA 校准器调查活动,以建立大量紧凑型无线电源,其位置足够精确,可用作 VLBI 相位参考校准器。我们报告了第二个纪元 VLBA 校准器调查活动 (VCS-II) 的结果,其中在 X 和 S 波段重新观测了 2400 个 VCS 源,以改进即将到来的国际天体参考框架 (ICRF3) 的第三次实现:以及提高它们作为 VLBI 相位参考校准器的实用性。在本次调查中,发现了大约 2062 个先前检测到的源和 324 个以前未检测到的源,并提出了修订位置。重新观测的源的平均位置不确定性分别从 RA 和赤纬的 1.14 和 1.98 mas 减少到 0.24 和 0.41 mas,或者减少了近 5 倍。X 和 S 波段的最小检测通量值分别约为 15 和 28 mJy,总通量中值约为 230 和 280 mJy。这些源中的绝大多数是平光谱源,约 82% 的光谱指数大于 -0.5。
更新日期:2016-05-27
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