  The G230LB grating used with STIS's CCD detector scatters red light. In red
objects, the scattered light mingles with the ultraviolet signal, causing
spurious short-wavelength flux and weakening absorption features. Recent
calibration observations characterize the scattered light using duplicate
observations with the MAMA detector and similar grating G230L. The full
two-dimensional spectrum contains little helpful information to mitigate the
scattered light problem. For one-dimensional, extracted spectra, the scattered
light can be approximately modeled as a ramped pedestal whose amplitude is
proportional to the object's V-band flux. We present formulae for scattered
light corrections. For stars warmer than G0 spectral type, correction is
superfluous. Off-slit-center positioning appears not to affect the properties
of the scattered light. Therefore, we are able to extrapolate correction
formulae for extended objects from the point source formulae. Polynomials for
flux corrections due to off-center slit positioning in the 0.2 arcsec slit are
also tabulated.
