  Results from the TESS mission showed that previous studies strngly
underestimated the number of slow rotators, revealing the importance of
studying those asteroids. For most slowly rotating asteroids (P > 12), no spin
and shape model is available because of observation selection effects. This
hampers determination of their thermal parameters and accurate sizes.
  We continue our campaign in minimising selection effects among main belt
asteroids. Our targets are slow rotators with low light-curve amplitudes. The
goal is to provide their scaled spin and shape models together with thermal
inertia, albedo, and surface roughness to complete the statistics. Rich
multi-apparition datasets of dense light curves are supplemented with data from
Kepler and TESS. In addition to data in the visible range, we also use thermal
data from infrared space observatories (IRAS, Akari and WISE) in a combined
optimisation process using the Convex Inversion Thermophysical Model (CITPM).
This novel method has so far been applied to only a few targets, and in this
work we further validate the method.
  We present the models of 16 slow rotators. All provide good fits to both
thermal and visible data. The obtained sizes are on average accurate at the 5%
precision, with diameters in the range from 25 to 145 km. The rotation periods
of our targets range from 11 to 59 hours, and the thermal inertia covers a wide
range of values, from 2 to <400 SI units, not showing any correlation with the
period. With this work we increase the sample of slow rotators with reliable
spin and shape models and known thermal inertia by 40%. The thermal inertia
values of our sample do not display a previously suggested increasing trend
with rotation period, which might be due to their small skin depth.
