NGC1851
 9 iterations.
Chebyshev coeffients a(0)T_0(u)+a(1)T_1(u)+..., where u is log (r/arcsec) mapped to [-1,1]
 a(0)=    19.680 +-  0.149
 a(1)=     6.422 +-  0.218
 a(2)=     0.845 +-  0.205
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=1+(r/r_c)^2, r_c=0.76
 a(0)=     4.2630
 a(1)=     1.3090
 a(2)=     0.3129
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set