We present a lensing study of 42 galaxy clusters imaged in Sloan Digital Sky Survey ( SDSS ) commissioning data .
Cluster candidates are selected optically from SDSS imaging data and confirmed for this study by matching to X–ray sources found independently in the ROSAT all sky survey ( RASS ) .
Five color SDSS photometry is used to make accurate ( \Delta z =0.018 ) photometric redshift estimates that are used to rescale and combine the lensing measurements .
The mean shear from these clusters is detected to 2 h ^ { -1 } Mpc at the 7- \sigma level , corresponding to a mass within that radius of ( 4.2 \pm 0.6 ) \times 10 ^ { 14 } h ^ { -1 } M _ { \sun } .
The shear profile is well fit by a power law with index -0.9 \pm 0.3 , consistent with that of an isothermal density profile .
Clusters are divided by X–ray luminosity into two subsets , with mean L _ { X } of ( 0.14 \pm 0.03 ) \times 10 ^ { 44 } and ( 1.0 \pm 0.09 ) \times 10 ^ { 44 } h ^ { -2 } ergs/s .
The average lensing signal is converted to a projected mass density based on fits to isothermal density profiles .
From this we calculate a mean r _ { 500 } ( the radius at which the mean density falls to 500 times the critical density ) and M ( < r _ { 500 } ) .
The mass contained within r _ { 500 } differs substantially between the low- and high-L _ { X } bins , with ( 0.7 \pm 0.2 ) \times 10 ^ { 14 } and 2.7 ^ { +0.9 } _ { -1.1 } \times 10 ^ { 14 } h ^ { -1 } M _ { \sun } respectively .
This paper demonstrates our ability to measure ensemble cluster masses from SDSS imaging data .
The full SDSS data set will include \gtrsim 1000 SDSS/RASS clusters .
With this large data set we will measure the M-L _ { X } relation with high precision and put direct constraints on the mass density of the universe .