Context : Weak lensing applied to deep optical images of clusters of galaxies provides a powerful tool to reconstruct the distribution of the gravitating mass associated to these structures .

Aims : We use the shear signal extracted by an analysis of deep exposures of a region centered around the galaxy cluster ABCG 209 , at redshift z \sim 0.2 , to derive both a map of the projected mass distribution and an estimate of the total mass within a characteristic radius .

Methods : We use a series of deep archival R-band images from CFHT-12k , covering an area of \sim 0.3 deg ^ { 2 } .
We determine the shear of background galaxy images using a new implementation of the modified Kaiser-Squires-Broadhurst KSB+ pipeline for shear determination , which we has been tested against the “ Shear TEsting Program 1 and 2 ” simulations .
We use mass aperture statistics to produce maps of the 2 dimensional density distribution , and parametric fits using both Navarro-Frenk-White and singular-isothermal-sphere profiles to constrain the total mass .

Results : The projected mass distribution shows a pronounced asymmetry , with an elongated structure extending from the SE to the NW .
This is in general agreement with the optical distribution previously found by other authors .
A similar elongation was previously detected in the X-ray emission map , and in the distribution of galaxy colours .
The circular NFW mass profile fit gives a total mass of M _ { 200 } = 7.7 ^ { +4.3 } _ { -2.7 } 10 ^ { 14 } { M } _ { \odot } inside the virial radius r _ { 200 } = 1.8 \pm 0.3 Mpc .

Conclusions : The weak lensing profile reinforces the evidence for an elongated structure of ABCG 209 , as previously suggested by studies of the galaxy distribution and velocities .