Abstract. We study the variance of the fluctuations in the number of lattice points in a ball and in a thin spherical shell of large radius centred at a Diophantine point. §1. Introduction. The distribution of lattice points has been extensively studied in the literature for its own sake, as well as with the aim of understanding the clustering of eigenvalues of quantum Hamiltonians associated with integrable systems. The eigenvalues of the "shifted" Laplaciangiven by the numbers |m − α| 2 , m ∈ Z d , and hence their counting function coincides with the number N (t) of lattice points inside a ball of a radius t, centred at α. It is immediately seen thatwhere B d is the volume of the unit ball in R d . Our object is the distribution of N (t), as a function of large t for a fixed α, in two regimes. First, we studyi.e. the normalized deviation of N (t) from its asymptotic value. Secondly, for ρ ∈ (0, 1), we investigatewhich is the normalized deviation of the number of lattice points in the spherical shell between the spheres of radii t + ρ and t from its asymptotics. Our aim is to study the asymptotics of weighted averages of F and S as t → ∞ and, in the case of S, as ρ → 0. Introduce a non-negative function ω ∈ C ∞ 0 (R) such that ω(t) = 0 for all t ≤ t 0 with some t 0 > 0 and ω(t) dt = 1. With the smooth measure induced by ω, we define for all T > 0 an averaging operator for a function f ∈ L 1 loc (R) by