NGC6101
 4 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)=    21.624 +-  0.401
 a(1)=     1.859 +-  0.657
 a(2)=     0.571 +-  0.413
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=1+(r/r_c)^2, r_c=1.78
 a(0)=     9.5237
 a(1)=    -0.5853
 a(2)=     2.1633
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set