The Zone of Avoidance:
Optical Compared to Near-Infrared Searches
Renee Kraan-Korteweg (U. of Guanajuato) &
Thomas Jarrett (IPAC/Caltech)
ASP Conference (2004)
Nearby Large-Scale Structures and the Zone of Avoidance
Eds. A.P. Fairall and P.A. Woudt
ABSTRACT
Galaxies uncovered in the Zone of Avoidance (ZOA) with deep optical
searches are compared to the distribution of objects in the 2MASS
Extended Source Catalog (2MASX). While the galaxy density of optical
surveys is strongly correlated to the dust content, and become
ineffective in uncovering the galaxy distribution at A_b > 3 mag,
this effect is much less severe in the NIR. Galaxies can be identified
in 2MASS at optical extinction layers of over 10 mag. However, star
density has been found to be the dominant limiting factor in the NIR
in the wider Galactic Bulge region where
optical surveys still do quite well.
Systematic positional offsets have also been found between objects in
the 2MASX and the optical ZOA as well as other galaxy catalogs. These
seem to have their origin in the astrometric reference frame used by
these surveys as well as different fitting algorithms when determining
positions (details are given in the Appendix). The astrometric offsets
between 2MASX and more recent galaxy catalogs (or on the Digitized
Sky Survey remeasured positions) are of the order of 1" -
1.5", comparable to the relative dispersion in positions between
these surveys. Still, it is advisable to take this effect into
account when combining galaxies from different catalogs for
observational purposes.
A postscript version (including color figures) of this paper
can be downloaded here: