On How to Extend the NIR Tully-Fisher Relation to be Truly All-Sky
  Dust extinction and stellar confusion by the Milky Way reduce the efficiency
of detecting galaxies at low Galactic latitudes, creating the so-called Zone of
Avoidance. This stands as a stumbling block in charting the distribution of
galaxies and cosmic flow fields, and therewith our understanding of the local
dynamics in the Universe (CMB dipole, convergence radius of bulk flows). For
instance, ZoA galaxies are generally excluded from the whole-sky Tully-Fisher
Surveys ($|b| \leq 5^\circ$) even if catalogued. We show here that by
fine-tuning the near-infrared TF relation, there is no reason not to extend
peculiar velocity surveys deeper into the ZoA. Accurate axial ratios ($b/a$)
are crucial to both the TF sample selection and the resulting TF distances. We
simulate the effect of dust extinction on the geometrical properties of
galaxies. As expected, galaxies appear rounder with increasing obscuration
level, even affecting existing TF samples. We derive correction models and
demonstrate that we can reliably reproduce the intrinsic axial ratio from the
observed value up to extinction level of about $A_J\simeq3$ mag ($A_V\sim11$
mag), we also recover a fair fraction of galaxies that otherwise would fall out
of an uncorrected inclination limited galaxy sample. We present a
re-calibration of the 2MTF relation in the NIR $J$, $H$, and $K_s$-bands for
isophotal rather than total magnitudes, using their same calibration sample.
Both TF relations exhibit similar scatter at high Galactic latitudes. However,
the isophotal TF relation results in a significant improvement in the scatter
for galaxies in the ZoA, and low surface brightness galaxies in general,
because isophotal apertures are more robust in the face of significant stellar
confusion.
