Gaia is still much higher precision

Forums General Discussion New Horizons Gaia is still much higher precision

Nick James

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.