MAGMO: Coherent magnetic fields in the star forming regions of the
  Carina-Sagittarius spiral arm tangent
  We present the pilot results of the `MAGMO' project, targeted observations of
ground-state hydroxyl masers towards sites of 6.7-GHz methanol maser emission
in the Carina-Sagittarius spiral arm tangent, Galactic longitudes 280 degrees
to 295 degrees. The `MAGMO' project aims to determine if Galactic magnetic
fields can be traced with Zeeman splitting of masers associated with star
formation. Pilot observations of 23 sites of methanol maser emission were made,
with the detection of ground-state hydroxyl masers towards 11 of these and six
additional offset sites. Of these 17 sites, nine are new detections of sites of
1665-MHz maser emission, three of them accompanied by 1667-MHz emission. More
than 70% of the maser features have significant circular polarization, whilst
only ~10% have significant linear polarization (although some features with up
to 100% linear polarization are found). We find 11 Zeeman pairs across six
sites of high-mass star formation with implied magnetic field strengths between
-1.5 mG and +3.8 mG and a median field strength of +1.6 mG. Our measurements of
Zeeman splitting imply that a coherent field orientation is experienced by the
maser sites across a distance of 5.3+/-2.0 kpc within the Carina-Sagittarius
spiral arm tangent.
