SiO Maser Survey towards off-plane O-rich AGBs around the orbital plane
  of the Sagittarius Stellar Stream
  We conducted an SiO maser survey towards 221 O-rich AGB stars with the aim of
identifying maser emission associated with the Sagittarius stellar stream. In
this survey, maser emission was detected in 44 targets, of which 35 were new
detections. All of these masers are within 5 kpc of the Sun. We also compiled a
Galactic SiO maser catalogue including ~2300 SiO masers from the literature.
The distribution of these SiO masers give a scale height of 0.40 kpc, while 42
sources deviate from the Galactic plane by more than 1.2 kpc, half of which
were found in this survey. Regarding SiO masers in the disc, we found both the
rotational speeds and the velocity dispersions vary with the Galactic plane
distance. Assuming Galactic rotational speed $\Theta$0 = 240 km/s , we derived
the velocity lags are 15 km/s and 55 km/s for disc and off-plane SiO masers
respectively. Moreover, we identified three groups with significant peculiar
motions (with 70% confidence). The most significant group is in the thick disc
that might trace stream/peculiar motion of the Perseus arm. The other two
groups are mainly made up of off-plane sources. The northern and southern
off-plane sources were found to be moving at ~33 km/s and 54 km/s away from the
Galactic plane, respectively. Causes of these peculiar motions are still
unclear. For the two off-plane groups, we suspect they are thick disc stars
whose kinematics affected by the Sgr stellar stream or very old Sgr stream
debris.
