NGC6541       c
 8 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)=    18.676 +-  0.126
 a(1)=     4.965 +-  0.215
 a(2)=     2.007 +-  0.167
 a(3)=     0.300 +-  0.145
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=r
 a(0)=     6.0413
 a(1)=     0.1359
 a(2)=     0.5683
 a(3)=     0.2775
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set