volume 13, issue S336, P373-376 2017
DOI: 10.1017/s1743921317010547
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Abstract: We report on the astrometric registration of VLBI images of the SiO and H 2 O masers in OH 231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the KVN and Source/Frequency Phase Referencing. This, for the first time, robustly confirms the alignment of the SiO masers, close to the AGB star, driving the bi-lobe structure with the water masers in the out-flow. We are able to trace the bulk motions for the H 2 O masers over the last few decades to be 19 km s −1 and deduce that th…

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