We use SDSS data to investigate the scaling relations of 127 NoSOCS and 56 CIRS galaxy clusters at low redshift ( z \leq 0.10 ) .
We show that richness and both optical and X-ray luminosities are reliable mass proxies .
The scatter in mass at fixed observable is \sim 40 % , depending on the aperture , sample and observable considered .
For example , for the massive CIRS systems \sigma _ { lnM 500 |N 500 } = 0.33 \pm 0.05 and \sigma _ { lnM 500 |Lx } = 0.48 \pm 0.06 .
For the full sample \sigma _ { lnM 500 |N 500 } = 0.43 \pm 0.03 and \sigma _ { lnM 500 |Lx } = 0.56 \pm 0.06 .
The scaling relations based only on the richer systems ( CIRS ) are slightly flatter than those based on the full sample , but the discrepancies are within 1- \sigma .
We estimate substructure using two and three dimensional optical data , verifying that substructure has no significant effect on the cluster scaling relations ( intercepts and slopes ) , independent of which substructure test we use .
For a subset of twenty-one clusters , we estimate masses from the M-T _ { X } relation using temperature measures from BAX .
The scaling relations derived from the optical and X-ray masses are indeed very similar , indicating that our method consistently estimates the cluster mass and yields equivalent results regardless of the wavelength from which we measure mass .
For massive systems , we represent the mass-richness relation by a function with the form { ln ( M _ { 200 } ) = A + B \times ln ( N _ { 200 } / 60 ) } , with M _ { 200 } being expressed in units of 10 ^ { 14 } M _ { \odot } .
Using the virial mass , for CIRS clusters , we find A = ( 1.39 \pm 0.07 ) and B = ( 1.00 \pm 0.11 ) .
For the same sample , but using the masses obtained by the caustic method , we get A = ( 0.64 \pm 0.14 ) and B = ( 1.35 \pm 0.34 ) .
If we consider the mass as estimated from T _ { X } ( for the subset of 21 clusters with T _ { X } available ) we derive A = ( 0.90 \pm 0.10 ) and B = ( 0.92 \pm 0.10 ) .
The relations based on the virial mass have a scatter of \sigma _ { lnM 200 |N 200 } = 0.37 \pm 0.05 , while \sigma _ { lnM 200 |N 200 } = 0.77 \pm 0.22 for the caustic mass and \sigma _ { lnM 200 |N 200 } = 0.34 \pm 0.08 for the temperature based mass .