  First, we describe a general procedure to produce high quality vector
magnetograms using the Imaging Vector Magnetograph (IVM) at Mees Solar
Observatory. At the spatial resolution 2"x2", the Stokes Q,U,V uncertainty
reaches 0.001-0.0005 in time-averaged data over 1-hour in the quiet Sun. When
vector magnetic fields are inferred from the time-averaged Stokes spectral
images of FeI 6302.5A, the resulting uncertainties are on the order of 10 G for
the longitudinal fields, 40 G for the transverse field strength and 9 degree
for the magnetic azimuth. The magnetic field inversion used in this work is the
"Triplet" code, which was developed and implemented in the IVM software package
by the late Barry J. LaBonte. The inversion code is described in detail in the
Appendix.
  Second, we solve for the absolute value of the vertical electric current
density, |Jz|, accounting for the above IVM problems, for two different active
regions. One is a single sunspot region (NOAA 10001 observed on 20 June 2002)
while the other is a more complex, quadrupolar region (NOAA10030 observed on 15
July 2002). We use a calculation that does not require disambiguation of 180
degree in the transverse field directions. The |Jz| uncertainty is on the order
of 7.0 mA m^-2. The vertical current density increases with increasing vertical
magnetic field. The rate of increase is about 1 -2 times as large in the
quadrupolar NOAA 10030 region as in the simple NOAA 10001, and it is more
spatially variable over NOAA 10030 than over NOAA 10001.
