NGC7078 (M15) c
 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)=    18.652 +-  0.098
 a(1)=     6.269 +-  0.171
 a(2)=     2.071 +-  0.155
 a(3)=     0.291 +-  0.109
 a(4)=     0.053 +-  0.103
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=r
 a(0)=     4.9613
 a(1)=     0.5399
 a(2)=     0.9260
 a(3)=    -0.0369
 a(4)=     0.0564
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set