KMTNet Nearby Galaxy Survey I. : Optimal strategy for low surface
  brightness imaging with KMTNet
  In hierarchical galaxy formation models, galaxies evolve through mergers and
accretions. Tidally-disrupted debris from these processes can remain as
diffuse, faint structures, which can provide useful insight into the assembly
history of galaxies. To investigate the properties of the faint structures in
outskirts of nearby galaxies, we conduct deep and wide-field imaging survey
with KMTNet. We present our observing strategy and optimal data reduction
process to recover the faint extended features in the imaging data of NGC 1291
taken with KMTNet. Through the dark sky flat-fielding and optimal sky
subtraction, we can effectively remove inhomogeneous patterns. In the combined
images, the peak-to-peak global sky gradients were reduced to less than
$\sim0.5$% and $\sim0.3$% of the original $B$- and $R$-band sky levels,
respectively. However, we find local spatial fluctuations in the background sky
which can affect the precise measurement of the sky value. Consequently, we can
reach the surface brightness of $\mu_{B,1\sigma} \sim$ 29.5 and
$\mu_{R,1\sigma}\sim$ 28.5 mag arcsec$^{-2}$ in azimuthally averaged
one-dimensional surface brightness profiles, that is mainly limited by the
uncertainty in the sky determination. These results suggest that the deep
imaging data produced by KMTNet are suitable to study the faint features of
nearby galaxies such as outer disks and dwarf companions, but unideal (not
impossible) to detect stellar halos. The one-dimensional profile revealed that
NGC 1291 appeared to have Type I disk out to $R$ $\sim$ 30 kpc with no obvious
color gradient and excess light due to a stellar halo was undetected.
