Orientation effect on the ligh curve shape of periodic methanol maser
  sources
  We report the results of our pilot millimeter observations of periodic maser
sources. Using SMA, we carried out 1.3\,mm observations of G22.357$+$0.066 and
G25.411$+$0.105, while ALMA 1.3 mm archival data was used in the case of
G9.62+0.19E. Two continuum cores (MM1 and MM2) were detected in
G22.357$+$0.066, while 3 cores (MM1 -- MM3) detected in G25.411$+$0.105.
Assuming dust-to-gas ratio of 100, we derived the masses of the detected cores.
Using the $^{12}$CO (2-1) and $^{13}$CO (2-1) line emission, we observed gas
kinematics tracing the presence of bipolar outflows in all three star-forming
regions. In the cases of G22.357$+$0.066 and G9.62+0.19E, both with similar
periodic maser light curve profiles, the outflowing gas is seen in the
north-west south-east direction. This suggest edge-on view of the 2 sources.
G25.411$+$0.105, with a contrasting light curve profile, show a spatially
co-located blue and red outflow lobes, suggesting a face-on view. Our results
suggest that orientation effects may play a role in determining the
characteristics of the light curves of periodic methanol masers.
