  We report the discovery of four transiting hot Jupiters from the HATSouth
survey: HATS-39b, HATS-40b, HATS41b and HATS-42b. These discoveries add to the
growing number of transiting planets orbiting moderately bright (12.5 < V <
13.7) F dwarf stars on short (2-5 day) periods. The planets have similar radii,
ranging from 1.33(+0.29/-0.20) R_J for HATS-41b to 1.58(+0.16/-0.12) R_J for
HATS-40b. Their masses and bulk densities, however, span more than an order of
magnitude. HATS-39b has a mass of 0.63 +/- 0.13 M_J, and an inflated radius of
1.57 +/- 0.12 R_J, making it a good target for future transmission
spectroscopic studies. HATS-41b is a very massive 9.7 +/- 1.6 M_J planet and
one of only a few hot Jupiters found to date with a mass over 5 M_J. This
planet orbits the highest metallicity star ([Fe/H] = 0.470 +/- 0.010) known to
host a transiting planet and is also likely on an eccentric orbit. The high
mass, coupled with a relatively young age (1.34 +0.31/-0.51 Gyr) for the host
star, are factors that may explain why this planet's orbit has not yet
circularised.
