We present the VEra Data Analyzer (VEDA) software package for Very Long Baseline Interferometry (VLBI) phase-referencing observations and parallax measurements. The Japanese VLBI project VLBI Exploration of Radio Astrometry (VERA) provides high-precision astrometric results at the 10 μas level. To achieve this precision, accurate calibration of the atmospheric phase fluctuation, the instrumental phase, and the source structural effect is required. VEDA specializes in phase-referencing data analysis, including these calibrations. In order to demonstrate its performance we analyzed H₂O maser observations of W 3(OH) and Orion KL with VERA. Their parallaxes were obtained to be 0.527 ± 0.016 mas and 2.459 ± 0.029 mas, respectively. We also analyzed their data using AIPS, which is widely used for VLBI data analysis, and confirmed that the parallaxes obtained using VEDA and AIPS are coincident within 10 μas. VEDA is available for high-precision parallax and proper motion measurements of Galactic maser sources.

中文翻译：

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VEDA：VERA数据分析软件，用于VLBI相位参考天文测量

我们提供用于超长基线干涉测量（VLBI）相位参考观测和视差测量的VEra数据分析器（VEDA）软件包。日本VLBI项目VLBI射电占星术探索（VERA）可提供10μas水平的高精度天文测量结果。为了达到此精度，需要对大气相位波动，仪器相位和源结构效应进行精确校准。VEDA专门从事相位参考数据分析，包括这些校准。为了证明其性能，我们分析了H ₂O maser用VERA观察W 3（OH）和Orion KL。他们的视差分别为0.527±0.016 mas和2.459±0.029 mas。我们还使用了广泛用于VLBI数据分析的AIPS分析了它们的数据，并确认使用VEDA和AIPS获得的视差在10μas内重合。VEDA可用于银河maser源的高精度视差和适当的运动测量。