Context :

Aims : The aim of this paper is to study the characteristics of the stellar populations and the metallicity distribution in the Galactic bulge .
We study the entire stellar population , but also retrieve information using only the red clump stars .

Methods : To study the characteristics of the stellar populations and the metallicity distribution in the Galactic bulge , we compared the output of the galaxy model TRILEGAL , which implements the Binney et al .
( 1997 ) bulge model , with observations from 2MASS and OGLE-II .
A minimisation procedure has been set up to retrieve the best fitting model with different stellar populations and metallicity distributions .

Results : Using the TRILEGAL code we find that the best model resembling the characteristics of the Galactic bulge is a model with the distance to the Galactic centre R _ { 0 } = 8.7 \pm ^ { 0.57 } _ { 0.43 } kpc , the major axis ratios of the bar 1 : \eta: \zeta = 1 : 0.68 \pm _ { 0.19 } ^ { 0.05 } : 0.31 \pm _ { 0.04 } ^ { 0.06 } , and the angle between the Sun-centre line and the bar \phi = 15 \hbox { $ { } ^ { \circ } $ } \pm _ { 12.7 } ^ { 13.3 } .
Using these parameters the best model is found for a burst of 8 Gyr , although it is almost indistinguishable from models with ages of 9 and 10 Gyr .
The metallicity distribution found is consistent with metallicity distributions in the literature based on spectroscopic results .

Conclusions :