NGC6144
 6 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)=    21.295 +-  0.165
 a(1)=     1.353 +-  0.247
 a(2)=     0.113 +-  0.213
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=1+(r/r_c)^2, r_c=1.70
 a(0)=     9.4025
 a(1)=     1.0596
 a(2)=     0.3125
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set