Revealing HI gas in emission and absorption on pc to kpc scales in a
  galaxy at z ~ 0.017
  We present a detailed study of the quasar-galaxy pair: J1243+4043 - UGC07904.
The sight line of the background quasar ( $z_q$= 1.5266) passes through a
region of the galaxy ($z_g$=0.0169) at an impact parameter of 6.9 kpc with high
metallicity (0.5 Z$_\odot$) and negligible dust extinction. We detect HI 21-cm
absorption from the foreground galaxy at arcsecond and milliarcsecond scales.
For typical cold neutral medium (CNM) temperatures in the Milky Way, this 21-cm
absorber can be classified as a damped Ly$\alpha$ absorber (DLA). We infer the
harmonic mean spin temperature of the gas to be $\sim$400 K and for a simple
two-phase medium we estimate the CNM-fraction to be $f_{\rm CNM}$ = 0.27. This
is remarkably consistent with the CNM fraction observed in the Galaxy and less
than that of high-redshift DLAs. The quasar exhibits a core-jet morphology on
milliarcsecond scales, corresponding to an overall extent of $\sim$9 pc at
$z_g$. We show that the size of CNM absorbing clouds associated with the
foreground galaxy is $>$5 pc and they may be part of cold gas structures that
extend beyond $\sim$35 pc. Interestingly, the rotation measure of quasar
J1243+4043 is higher than any other source in samples of quasars with high-$z$
DLAs. However, we do not find any detectable differences in RMs and
polarization fraction of sight lines with or without high-$z$ ($z\ge2$) DLAs or
low-$z$ ($z\le0.3$) 21-cm absorbers. Finally, the foreground galaxy UGC07904 is
also part of a galaxy group. We serendipitously detect HI 21-cm emission from
four members of the group, and a $\sim$80 kpc long HI bridge connecting two of
the other members. The latter, together with the properties of the group
members, suggests that the group is a highly interactive environment.
