An interesting article on The NASA New Horizons web site. On April 22nd and 23rd the spacecraft will take images of Proxima Centauri, and Wolf 359. Simultaneously Astronomers on Earth including Amateurs have been asked to take images of these stars and there fields. Then using the 5 billion mile baseline of the spacecraft’s distance from Earth, extremely accurate parallax’s will be obtained. Wolf 359 is well placed at the moment.
It’s a nice outreach activity and the baseline is certainly much larger than the 2au baseline that Gaia has but the resolution of the LORRI camera on NH in 4×4 bin mode is only around 5 arcsec (2.3 m FL, 13.5 um pixels). The current Gaia DR2 error for the parallax of Proxima is 0.2 milli-arcsec (mas). Assuming a high SNR in the images LORRI might get astrometry accurate to 50-100 mas. The 25 times improvement in baseline won’t compensate for the factor of 250 loss in precision. The NASA publicity doesn’t really make this very clear.
Proxima is too far south for us at a declination of 62 deg S. Wolf 359 is a bit further away (7.9 light years compared to proxima’s 4.2) but it is visible from the northern hemisphere as faint red dwarf in Leo.