I make a new evaluation of the microlensing optical depth toward the Galactic bar from Difference Image Analysis ( DIA ) of the MACHO Collaboration .
First , I present supplementary evidence that MACHO field 104 located at ( l,b ) = ( 3 \hbox { $ . ^ { \circ } $ } 11 , -3 \hbox { $ . ^ { \circ } $ } 01 ) is anomalous in terms of the event duration distribution .
I argue that both the event durations and the very high optical depth of field 104 are not representative and , therefore , exclude this field as an outlier .
In addition , I eliminate field 159 at ( l,b ) = ( 6 \hbox { $ . ^ { \circ } $ } 35 , -4 \hbox { $ . ^ { \circ } $ } 40 ) based mainly on its separate location , but also on unexplained statistical properties of the event durations .
The remaining six DIA fields form a very homogeneous and spatially compact set that is very suitable for averaging .
The weighting of the optical depth values for these six DIA fields results in a total optical depth \tau _ { tot } = 2.01 ^ { +0.34 } _ { -0.32 } \times 10 ^ { -6 } at ( l,b ) = ( 2 \hbox { $ . ^ { \circ } $ } 22 , -3 \hbox { $ . ^ { \circ } $ } 18 ) .
If a fraction of all sources , f _ { disk } , assumed to be in the disk , does not contribute to microlensing , then the optical depth toward the sources in the bar is \tau _ { bar } = 2.23 ^ { +0.38 } _ { -0.35 } \times 10 ^ { -6 } \frac { 0.9 } { 1 - f _ { disk } } .
Both \tau _ { tot } and \tau _ { bar } are substantially lower than the original estimates of Alcock et al .
Most of the change in the DIA-based optical depths comes from a more appropriate statistical treatment of the results in individual fields and not from the removal of fields 104 and 159 .
When taken together with \tau _ { bar } = 1.4 \pm 0.3 \times 10 ^ { -6 } at ( l,b ) = ( 3 \hbox { $ . ^ { \circ } $ } 9 , -3 \hbox { $ . ^ { \circ } $ } 8 ) as derived from clump giants , this new result suggests that the conclusions from microlensing experiments are in reasonable agreement with expectations from infrared-based Galactic models .

Subject Headings : Galaxy : center — Galaxy : structure — gravitational lensing