& 21.4 & NUS\
\
[[*XMM–Newton*]{}]{}& 0145670101 & 2003-03-05 & 44.5 & XMM\
[[*NuSTAR*]{}]{}& 60061061002 & 2012-10-05 & 15.5& NUS1\
[[*NuSTAR*]{}]{}& 60061061004 & 2013-02-14 & 12.0& NUS2\

Spectral analysis {#sec:analysis}
=================

Spectral analysis and model fitting was carried out with the [[xspec]{}]{} 12.10 package [@arnaud1996], using the ${\chi^{2}}$ minimisation technique. Errors are quoted at the 90 per cent confidence level for one interesting parameter. We assumed the element abundances of [@angr] and the photoelectric absorption cross-sections of [@vern]. We fitted the IBIS spectra over the full 20–300 keV energy band.

NGC 4388
--------

The emission of this source below $\sim 3$ keV is known to be dominated by emission from a hot plasma in an extended X-ray nebula at kpc scales [@beckmann2004]. Therefore, since our main focus is the AGN-dominated hard X-ray emission, we restricted the broad-band spectral analysis to the data above 4 keV. We fitted the [[*XMM–Newton*]{}]{} and [[*NuSTAR*]{}]{} spectra over the 4–10 keV and 4–79 keV energy bands, respectively.

### The IBIS spectrum

As a first step, we focused on the IBIS spectrum, with a twofold purpose: first, testing for the presence of a curvature at high energies and, secondly, a consistency check with the low-energy spectra. 