Calculating planks constant from expariment data

[wallace5]

1. I am trying to calculate planks constant from data taken in my lab. I measured intensity over the range of wavelengths from 350nm to 900nm the blackbody(furnace) i am measuring is at approx 800kelvin



2. using planks radiation law: Iλ(T,λ)=(2C2 h)/λ5 [1/(e(hC/(λK T))-1]



3.Factored to get

λ5I=2(c2)hehc/λkT

ln(λ5I)=ln(2c2h)-(hc/kT)1/λ
y=b-mx

so I think if i plot ln(λ5I) vs. 1/λ i should be able to extract the slope


m=-hc/λkT

and factoring

h=-mkT/c


when i do this though i get a value of almost 5000 for the slope which is far to high

using planks constant in m=-hc/λkT i find that m should be about 0.00001773


does anyone have a suggestion on what i'm doing wrong
1. The problem statement, all variables and given/known data



2. Relevant equations



3. The attempt at a solution