  We present HST WFPC2 and STIS imaging of the low metallicity galaxy NGC 6822,
performed as part of a study of the young stellar populations in the galaxies
of the Local Group. Eleven WFPC2 pointings, with some overlap, cover two
regions, extending over 19'x19' and 13'x13' respectively, off the galaxy
center. One 25x25'' field observed with STIS' FUV- and NUV- MAMA, includes
Hodge's OB8 association and the HII region Hubble V. We derive the physical
parameters of the stars in the fields and the extinction by comparing the
photometry to grids of model magnitudes. The environments studied in this work
include one of the most luminous (in Halpha) HII regions in the Local Group
(Hubble V) with a compact star cluster, a typical OB association (OB15), the
sparse field population and the outskirts of NGC6822. The color-magnitude
diagrams show similar ages of few Myrs for both OB8 and OB15. The density [per
unit area] of hot massive stars in the core of the OB8 association is higher
than in OB15 by a factor of 12, while the total stellar mass formed is similar.
In both OB15 and OB8 massive star candidates are found. The average extinction
is found to vary among the three environments studied: E(B-V) = 0.22 in the
outer regions, E(B-V) = 0.27 in the fields East of the galaxy main bar, and
E(B-V) = 0.40 in the HII region Hubble V. A quantitative discussion of the
applicability of the reddening-free-index method for photometric determination
of stellar parameters is provided for the filters used in this work, based on
our grids of stellar models.

Astrophysics