Distance to Proxima Centauri (Gaia VS New Horizons parallax program)
LORRI will be used in 4x4 mode, which yields 4-arcsec pixels.  The error in positions is unlikely to be better than 1%, or 40 mas, about 200x larger than Gaia's error.  NH has a baseline ~20x larger, but this means it still misses Gaia by ~10x.

The date was selected for New Moon to help Earth observers find the two targets.  There is no Earth analogue for LORRI, but it should be readily matched by amateur rigs.  The project will use professional ~0.5 - 1.0m telescopes to get Earth obs.  Simultaneous Earth obs are not strictly required, but the simultaneous times are offered to conduct the aesthetically purest demonstration of instantaneous parallaxes.