  Imaging spectropolarimetry is a new observing mode on the Advanced Camera for
Surveys (ACS) aboard the Hubble Space Telescope (HST) that was commissioned in
Cycle 30 and is available to HST observers starting in Cycle 31 (i.e., from
2023). It is a technique that is accessible from ground-based observatories,
but the superb spatial resolution afforded by HST/ACS combined with the
slitless nature of HST/ACS grism spectroscopy opens up the possibility of
studying polarized extended emission in a way that is not currently possible
even with Adaptive Optics facilities on the ground. This mode could help to
study interesting targets including (but not limited to) QSOs, AGN and Radio
Galaxies, ISM Dust Properties, Pre-Planetary Nebulae, Proto-Planetary and
Debris Disks, Supernovae/Supernova Remnants, and Solar System objects. This
research note presents the preliminary results from the calibration programs
used to calibrate imaging spectropolarimetry on HST/ACS.
