We report on the X-ray dust-scattering features observed around the afterglow of the gamma ray burst GRB 160623A .
With an XMM-Newton  observation carried out \sim 2 days after the burst , we found evidence of at least six rings , with angular size expanding between \sim 2 and 9 arcmin , as expected for X-ray scattering of the prompt GRB emission by dust clouds in our Galaxy .
From the expansion rate of the rings , we measured the distances of the dust layers with extraordinary precision : 528.1 \pm 1.2 pc , 679.2 \pm 1.9 pc , 789.0 \pm 2.8 pc , 952 \pm 5 pc , 1539 \pm 20 pc and 5079 \pm 64 pc .
A spectral analysis of the ring spectra , based on an appropriate dust-scattering model ( BARE-GR-B from \citealt zubko04 ) and the estimated burst fluence , allowed us to derive the column density of the individual dust layers , which are in the range 7 \times 10 ^ { 20 } -1.5 \times 10 ^ { 22 } cm ^ { -2 } .
The farthest dust-layer ( i.e .
the one responsible for the smallest ring ) is also the one with the lowest column density and it is possibly very extended , indicating a diffuse dust region .
The properties derived for the six dust-layers ( distance , thickness , and optical depth ) are generally in good agreement with independent information on the reddening along this line of sight and on the distribution of molecular and atomic gas .