We used Subaru observations of A1689 (z = 0.183) to derive an accurate, model-independent mass profile for the entire cluster, r ≾ 2Mpc/h, by combining magnification bias and distortion measurements. The projected mass profile steepens quickly with increasing radius, falling away to zero at r ~1.0Mpc/h, well short of the anticipated virial radius. Our profile accurately matches onto the inner profile, r ≾ 200kpc/ h, derived from deep HST / ACS images. The combined ACS and Subaru information is well fitted by an NFW profile with virial mass, (1.93 ± 0.20) X 1015M⊙, and surprisingly high concentration, Cvir = 13.7+1.4-1.1, significantly larger than theoretically expected (Cvir ≃4), corresponding to a relatively steep overall profile. These results are based on a reliable sample of background galaxies selected to be redder than the cluster E/SO sequence. By including the faint blue galaxy population a much smaller distortion signal is found, demonstrating that blue cluster members significantly dilute the true signal for r ≾ 400kpc/ h. This contamination is likely to affect most weak lensing results to date.

• KEIICHI UMETSU(Institute of Astronomy and Astrophysics)
• TOM BROADHURST(Astronomical Institute, Tohoku University)
• MASAHIRO TAKADA(School of Physics and Astronomy, Tel Aviv University)
• Xu KONG(National Astronomical Observatory of Japan)