of following polarity embedded in the plage, as seen in Figure \[fig:irisaia\]. The flare developed in a bursty manner, with UV kernels of various intensity appearing in rapid succession, in particular running north-east to south-west along the length of the plage ribbon. At the same time, the ribbons expanded roughly perpendicularly to their length, as in the canonical flare model.

Several authors have by now described many aspects of the flare, including the precursor phase [@2016ApJ...823L..19Z], the eruption of a filament and slipping motion of flare loops [@2016ApJ...823...41D], the presence of [*quasi-periodic pulsations*]{} [@2015ApJ...807...72L; @2015SoPh..290.3625S; @2017SoPh..292...11N], and the occurrence of chromospheric evaporation [@2015ApJ...811..139T; @2015ApJ...813...59L] and its relation with chromospheric condensation (Paper I). Representative movies depicting the flare evolution are available in, e.g., @2015ApJ...811..139T and @2016ApJ...823...41D.

As discussed in the introduction, the present paper focuses on the chromospheric emission during the flare’s impulsive phase, and its diagnostic potential with respect to radiative hydro-dynamical modeling. To this end, we will discuss mostly the hard X-ray (HXR) observations obtained by Fermi/GBM [@2009ApJ...702..791M] and the UV spectra and images acquired by IRIS [@2014SoPh..289.2733D], in particular around the time of maximum IRIS UV emission. GOES soft X-ray (SXR) light curves and SDO/AIA images at various 