This project is a southern hemisphere counterpart to the BeSSeL Survey being performed with the VLBA. The primary aim of this project is
to use VLBI observations to measure accurate distances to and proper
motions of 6.7 GHz methanol masers in the third and fourth quadrants of
the Galaxy. VLBA and VERA observations of masers in the first and
second quadrants suggest high-mass star formation regions on average
orbit the Galaxy 15 km/s more slowly than expected from circular orbit
models and measure a circular rotation speed for the Sun of 254 km/s.
These results are however, derived from limited data and remain
controversial. More measurements of parallax and proper motion for
high-mass star forming regions in the southern sky of the Milky Way are
critical to better constrain and confirm these results. The
methanol masers targeted in this project are exclusively associated
with young, high-mass star formation regions and as such they are ideal
for tracing spiral arm structures and high-mass star formation in the
inner Galaxy.
This project commenced in 2010 and aims to obtain parallaxes for 30
southern 6.7 GHz methanol masers by the end of 2014. To date we
have completed the observations for four sources (observed as two pairs
of two), analysis of these data is currently in progress. Two
epochs have been completed for a further two sources. Details of
the sources observed and the status of those observations are presented here