We perform a measurement of the mass–richness relation of the redMaPPer galaxy cluster catalogue using weak lensing data from the Sloan Digital Sky Survey .
We have carefully characterized a broad range of systematic uncertainties , including shear calibration errors , photo- z biases , dilution by member galaxies , source obscuration , magnification bias , incorrect assumptions about cluster mass profiles , cluster centering , halo triaxiality , and projection effects .
We also compare measurements of the lensing signal from two independently-produced shear and photometric redshift catalogues to characterize systematic errors in the lensing signal itself .
Using a sample of 5,570 clusters from 0.1 \leq z \leq 0.33 , the normalization of our power-law mass vs . \lambda relation is \log _ { 10 } [ M _ { 200 m } / h ^ { -1 } M _ { \odot } ] = 14.344 \pm 0.021 ( statistical ) \pm 0.023 ( systematic ) at a richness \lambda = 40 , a 7 per cent calibration uncertainty , with a power-law index of 1.33 ^ { +0.09 } _ { -0.10 } ( 1 \sigma ) .
The detailed systematics characterization in this work renders it the definitive weak lensing mass calibration for SDSS redMaPPer clusters at this time .