  The value of accurately knowing the absolute calibration of the polarizing
elements in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS)
becomes especially important when conducting studies which require measuring
degrees of polarization of close to 1% in the near infrared. We present a
comprehensive study of all previously observed polarimetric standards using the
NIC2 camera on NICMOS. Considering both pre- and post-NICMOS Cooling System
observations we find variations in the polarimetry consistent with the effects
of sub-pixel mis-alignments and the point spread function. We also measure
non-zero results from unpolarized standards indicating an instrumental
polarization of p ~ 1.2%, theta ~ 88degrees. The lack of polarized and
unpolarized standard stars with which to perform a comprehensive calibration
study means we cannot be confident that the current calibration will be
effective for a number of recent large NICMOS GO programs. Further observations
of polarimetric standards are needed in order to fully characterize the
behavior of NICMOS at around p=1%.
