First mm-VLBI observations between the TRAO 14-m and the NRO 45-m telescopes: Observations of 86 GHz SiO masers in VY canis majoris

We have made VLBI observations at 86 GHz using a 1000-km baseline between Korea and Japan with successful detections of SiO v = 1, J = 2-1 maser emissions from VY CMa and Orion KL in 2001 June. This was the first VLBI result for this baseline and the first astronomical VLBI observation for the Korean telescope. Since then, we observed SiO v = 1, J = 2-1 maser emission in VY CMa in 2002 January and 2003 February and derived the distributions of the maser emissions. Our results show that the maser emissions extend over 2-4 stellar radii, and were within the inner radius of the dust shell. We observed other SiO maser sources and continuum sources, and 86-GHz continuum emissions were detected from three continuum sources. It was verified that this baseline has a performance comparable to the most sensitive baseline in the VLBA and the CMVA, and is capable of investigating the proper motions of maser features in circumstellar envelopes using monitoring observations.