Probing the circumnuclear absorbing medium of the buried AGN in NGC 1068
  through NuSTAR observations
  We present the results of the latest NuSTAR monitoring campaign of the
Compton-thick Seyfert 2 galaxy NGC 1068, composed of four $\sim$50 ks
observations performed between July 2017 and February 2018 to search for flux
and spectral variability on timescales from 1 to 6 months. We detect one
unveiling and one eclipsing event with timescales less than 27 and 91 days,
respectively, ascribed to Compton-thick material with
$N_H=(1.8\pm0.8)\times10^{24}$ cm$^{-2}$ and $N_H\geq(2.4\pm0.5)\times10^{24}$
cm$^{-2}$ moving across our line of sight. This gas is likely located in the
innermost part of the torus or even further inward, thus providing further
evidence of the clumpy structure of the circumnuclear matter in this source.
Taking advantage of simultaneous Swift-XRT observations, we also detected a new
flaring ULX, at a distance $d\sim$30" (i.e. $\sim$2 kpc) from the nuclear
region of NGC 1068, with a peak X-ray intrinsic luminosity of
$(3.0\pm0.4)\times10^{40}$ erg s$^{-1}$ in the 2-10 keV band.
