Registration of H${}_2$O and SiO masers in the Calabash Nebula, to confirm the Planetary Nebula paradigm

Richard Dodson, Maria Rioja, Valentin Bujarrabal +4

We report on the astrometric registration of VLBI images of the SiO and water masers in OH231.8+4.2, the iconic Proto-Planetary Nebula also known as the Calabash nebula, using the…