I'm trying to identify a distribution presented to me as the "Van Loon distribution". My professor's book on Electrical Measurements presents 3 distributions that model the probability density function of the error an observation is expected to have given a set of already obtained observations. These are the normal distribution, the "Van Loon" distribution and the Laplace distribution. The problem is that I can't find any other reference to a Van Loon distribution on Google and I suspect my professor is using a lesser known name for an otherwise common distribution. The distribution is: $$\psi(\delta) = \frac{\alpha e^{\alpha \delta}}{(1+e^{\alpha \delta})^2}$$ Has anyone seen this distribution before?

This seems to be the logistic distribution with location $\mu=0$ and scale $s = 1/\alpha$. As noted by Michael Hardy in the comments, the PDF is symmetric [about $\mu$].