LW Column 24 is disconnected (i.e., the detector is still active but
no data are available). Since one doesn't know exactly when the
observation will be scheduled, the orientation on the sky of the
missing column is not known. Therefore, if good data is needed across
the whole array, a raster must be performed or additional pointings
with an offset step size and geometry sufficient to shift the missing
column cleanly onto a good portion of the array. Column 24 runs in the
satellite Z direction and is offset from the center of the array in
the satellite Y direction (+M for an unconstrained raster). Details
of how to deal with the missing column are given in Chapter 4.