Arp2 (1927-30)
21 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)=     2.245 +-  0.403
 a(1)=     2.350 +-  0.674
 a(2)=     0.194 +-  0.518
 a(3)=    -0.142 +-  0.415
Power-of-x coeffients a(0)+a(1)x+a(2)x^2+..., where x=1+(r/r_c), r_c=2.11
 a(0)=    -0.8997
 a(1)=     0.1986
 a(2)=     4.4163
 a(3)=    -1.6661
log r(arcsec)   mu_V    mu_V(fitted)  residual   weight  data set