Milky Way Tomography with the SkyMapper Southern Survey. II. Photometric
  Re-calibration of SMSS DR2
  We apply the spectroscopy-based stellar-color regression (SCR) method to
perform an accurate photometric re-calibration of the second data release from
the SkyMapper Southern Survey (SMSS DR2). From comparison with a sample of over
200,000 dwarf stars with stellar atmospheric parameters taken from GALAH+ DR3
and with accurate, homogeneous photometry from $Gaia$ DR2, zero-point offsets
are detected in the original photometric catalog of SMSS DR2, in particular for
the gravity- and metallicity-sensitive $uv$ bands. For $uv$ bands, the
zero-point offsets are close to zero at very low extinction, and then steadily
increase with $E (B - V)$, reaching as large as 0.174 and 0.134 mag
respectively, at $E (B - V) \sim 0.5$ mag. These offsets largely arise from the
adopted dust term in the transformations used by SMSS DR2 to construct
photometric calibrators from the ATLAS reference catalog. For the $gr$ bands,
the zero-point offsets exhibit negligible variations with SFD $E(B - V )$, due
to their tiny coefficients on the dust term in the transformation. Our study
also reveals small, but significant, spatial variations of the zero-point
offsets in all $uvgr$ bands. External checks using Str\"omgren photometry, WD
loci and the SDSS Stripe 82 standard-star catalog independently confirm the
zero-points found by our revised SCR method.
