Consider a uniform probability distribution on a circle of radius r, i.e. $\{(x,y) \in \mathbb{R}^2: x^2 + y^2 = r^2 \}$.If we wish to project onto the x-axis, we can consider each point on the circle to contribute $\delta(x-rcos(\theta))$. Then averaging over all possible values of $\theta$ yields the following distribution:
$Pr(x) = \frac{1}{\pi\sqrt{r^2-x^2}}$
Intriguingly, the Fourier transform of Pr(x) happens to be the zero order Bessel function of the first kind, i.e. $J_0(2\pi r f)$
Question: What is this distribution Pr(x) called?
I distinctly recall it having a Wikipedia page dedicated to it, and it being named after some mathematician. It is decidedly not the Arcsine distribution, as I have seen it mistakenly referred to occasionally!