Estimating powerlaws via linear regression hardly ever works – see Power-law distributions in empirical data for details and proper ML based estimation algorithms. Unfortunately, there only seems to be an abandoned package in Julia …
In any case, here is a quick estimate on your data using formula (B.17) from the paper and an arbitrary x_{min}:
julia> xmin = 23
23
julia> x = degrees[degrees .> xmin];
julia> 1 + inv(mean(log.(x ./ (xmin - 1/2))))
2.810142626941318
which is already much closer to the analytic exponent.