IC1276 (Pal7)
 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)=    23.742 +-  0.184
 a(1)=     2.761 +-  0.317
 a(2)=     0.617 +-  0.227
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=1+(r/r_c)^2, r_c=1.68
 a(0)=     9.7268
 a(1)=     0.2242
 a(2)=     0.7218
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set