We observed the 43 GHz v =1 , 2 & 3 and 86 GHz v =1 SiO maser transitions quasi-simultaneously for a Mira-variable dominated sample of over 80 sources from the Bulge Asymmetries and Dynamical Evolution ( BAaDE ) project , using ATCA , and statistically compared the relative line strengths .
On average , the 43 GHz v =1 line is brighter than the 86 GHz v =1 line by a factor of 1.36 ^ { +0.15 } _ { -0.14 } .
As a result , an 86 GHz v =1 observed sample can be observed to 85.9 % of the distance of a 43 GHz v =1 observed sample using the same sensitivity .
We discuss what impact this may have on the BAaDE Galactic plane survey using the VLA and ALMA .
Despite fewer v =3 detections , specific trends are discerned or strengthened when the 43 GHz v =3 line is detected .
In particular the 43 GHz and 86 GHz v =1 lines are on average equal for sources with no detectable 43 GHz v =3 emission , but the 43 GHz v =1 line strength is on average about twice as bright as the 86 GHz v =1 line for sources with detectable 43 GHz v =3 emission .
Some weak correlations are found between line strengths and Midcourse Space Experiment ( MSX ) flux densities and colors , which are tightened when considering only sources with detectable 43 GHz v =3 emission .
We discuss these trends in the context of a radiative pumping model to highlight how the 43 GHz v =3 line , when coupled with the v =1 and v =2 lines , can further our understanding of variable conditions like density in the circumstellar envelopes .