We reanalyse the measurements of parallax , proper motion , and line-of-sight velocity for 18 masers in high mass star-forming regions presented by ( ) .
We use a likelihood analysis to investigate the distance of the Sun from the Galactic centre , R _ { 0 } , the rotational speed of the local standard of rest , v _ { 0 } , and the peculiar velocity of the Sun , \mathbf { v _ { \odot } } , for various models of the rotation curve , and models which allow for a typical peculiar motion of the high mass star-forming regions .

We find that these data are best fit by models with non-standard values for \mathbf { v _ { \odot } } or a net peculiar motion of the high mass star-forming regions .
We argue that a correction to \mathbf { v _ { \odot } } is much more likely , and that these data support the conclusion of ( ) that V _ { \odot } should be revised upwards from 5.2 \mathrm { km s } ^ { -1 } to 11 \mathrm { km s } ^ { -1 } .
We find that the values of R _ { 0 } and v _ { 0 } that we determine are heavily dependent on the model we use for the rotation curve , with model-dependent estimates of R _ { 0 } ranging from 6.7 \pm 0.5 \mathrm { kpc } to 8.9 \pm 0.9 \mathrm { kpc } , and those of v _ { 0 } ranging from 200 \pm 20 \mathrm { km s } ^ { -1 } to 279 \pm 33 \mathrm { km s } ^ { -1 } .
We argue that these data can not be thought of as implying any particular values of R _ { 0 } or v _ { 0 } .
However , we find that v _ { 0 } / R _ { 0 } is better constrained , lying in the range 29.9 - 31.6 \mathrm { km s } ^ { -1 } \mathrm { kpc } ^ { -1 } for all models but one .