f1(x)=a11*exp(-((x-a12)/a13)**2/2)
a11 = 3500 ; a12 = 230  ; a13 = 25  
f2(x)=a21*exp(-((x-a22)/a23)**2/2)
a21 = 500 ; a22 = 120  ; a23 = 25  
fit [80 : 300] f1(x)+f2(x)  "1.46-nagao-1.hist"  using 1:2:($2**0.5) via a11,a12,a13,a21,a22,a23
plot f1(x)+f2(x),  f1(x), f2(x) , "1.46-nagao-1.hist"