Computed polarization spectra for repeated measurements of the unpolarized standard star HR2943. Slit-guiding and charge-shuffling was disabled to demonstrate the typical effects introduced by atmospheric transmission variation (clouds), telescope jitter, guiding errors and other instrumental errors on the continuum polarization. The intensity spectrum in the bottom row shows all 19 extracted spectral orders and the associated blaze functions. Each quv continuum polarization measurement shows substantial variation of over 2%. There are two components to the quv spectra: the spectrograph calibration function and the telescope induced polarization. See text for details.