It has become customary to assume arbitrarily that the plane is exactly lined up with the line of sight from LOCATION@1 -LRB- this produces the lowest possible mass consistent with the spectral line measurements -RRB- .

It has become customary to arbitrarily assume that the plane is exactly lined up with the line of sight from LOCATION@1 -LRB- this produces the lowest possible mass consistent with the spectral line measurements -RRB- .
