  We report the discovery of a young massive stellar cluster embedded in an
extended HII region, invisible at optical wavelengths where the extinction is
$A_V \approx 28$ magnitudes, associated with the IRAS source 16177-5018. $J, H$
and nb$K$ imaging photometry combined with the $K_S$ 2MASS data show the
presence of sources with infrared excess emission at 2.2 $\mu$m, concentrated
in an area of about one square parsec around a massive young stellar object
identified as the IRAS source. This object has a near-mid infrared spectral
index betweem 2.2 and 25 $\mu$m $\alpha({\rm IR}) = d {\rm log}(\lambda
F_\lambda)/d {\rm log} \lambda $ =4.78, characteristic of compact H II regions,
with bolometric luminosity, inferred from the integrated near to far-infrared
flux density of $2.8 \times 10^5 L_\odot$, which corresponds to a ZAMS star of
about $42 M_\odot$. From the color-magnitude diagram we were able to classify
the majority of the cluster members as reddened massive stars earlier than
spectral type B5.

Astrophysics