  The SED of the lensed z=6.56 galaxy HCM6A behind the cluster Abell 370 has
been analysed. We find clear indications for the presence of dust in this
galaxy, and we estimate the properties of its stellar populations (SFR, age,
etc.). From its estimated luminosity, L~(1-4)e.+11 Lsun, this galaxy ranks as a
luminous infrared galaxy. This case is then used to examine the detectability
of high-z galaxies with Herschel and ALMA. It is evident that with the use of
strong gravitational lensing SPIRE/Herschel observations could provide very
interesting information on z > 5 galaxies. Strong synergies between
ground-based near-IR instruments on 8-10m class telescopes and ELTs, Herschel,
the JWST, and ALMA can be expected for the exploration of the first galaxies in
the Universe.

Astrophysics