  The highly obscured radio-bright galaxy PKS1343-601 (l=309.7, b=+1.8) has
been suspected to mark the centre of a hitherto unknown cluster in the Great
Attractor region. As such it presents an ideal region for a search of galaxies
in the near-infrared (NIR) and an in-depth study of their colours as a function
of extinction. A visual search of a ~30 square-degree area centered on this
radio galaxy on images of the NIR DENIS survey (IJK) revealed 83 galaxies
(including two AGNs) and 39 possible candidates. Of these, 49 are also listed
in the 2MASS Extended Source Catalog 2MASX. Taking the IRAS/DIRBE extinction
values (Schlegel et al. 1998) at face value, the absorption in the optical
(A_B) ranges from ~2m to over 100m across the Galactic Plane. Comparing the
detections with other systematic surveys, we conclude that this search is
highly complete up to the detection limits of the DENIS survey and certainly
surpasses any automatic galaxy finding algorithm applied to crowded areas. The
NIR galaxy colours from the 7" aperture were used as a probe to measure total
Galactic extinction. A comparison with the IRAS/DIRBE Galactic reddening maps
suggests that the IRAS/DIRBE values result in a slight overestimate of the true
extinction at such low Galactic latitudes; the inferred extinction from the
galaxy colours corresponds to about 87% of the IRAS/DIRBE extinctions. Although
this determination still shows some scatter, it proves the usefulness of NIR
surveys for calibrating the IRAS/DIRBE maps in the extinction range of 2m < A_B
< 12m.
