  This paper discusses a couple of approaches to removing instrument gain and
baseline variation from observations of the CMB anisotropy. These techniques
were tested on the COBE DMR data, a balloon experiment, and by monte carlo
simulations. This work, though considered technical, is made available because
CMB anisotropy mapping data processing is currently very active and a
significant number of groups are working on this issue. Specifically,
time-ordered estimates of the gain and baseline via fitting to limited sections
of data or to the full or a large section of data are considered and compared.
An expression is given for the correlation between pixels introduced by the
residual baseline and removal technique.
