NGC6522       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)=    17.858 +-  0.082
 a(1)=     2.773 +-  0.121
 a(2)=     0.842 +-  0.115
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=r
 a(0)=     7.0221
 a(1)=     0.5653
 a(2)=     1.0443
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set