NGC6584
 3 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)=    20.171 +-  0.250
 a(1)=     2.831 +-  0.379
 a(2)=     0.539 +-  0.354
 a(3)=     0.326 +-  0.309
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=1+(r/r_c), r_c=1.21
 a(0)=     7.4645
 a(1)=     2.8636
 a(2)=    -1.7806
 a(3)=     0.6476
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set