  We provide a scheme to correct asteroid astrometric observations for star
catalog systematic errors due to inaccurate star positions and proper motions.
As reference we select the most accurate stars in the PPMXL catalog, i.e.,
those based on 2MASS astrometry. We compute position and proper motion
corrections for 19 of the most used star catalogs. The use of these corrections
provides better ephemeris predictions and improves the error statistics of
astrometric observations, e.g., by removing most of the regional systematic
errors previously seen in Pan-STARRS PS1 asteroid astrometry. The correction
table is publicly available at
ftp://ssd.jpl.nasa.gov/pub/ssd/debias/debias_2014.tgz and can be freely used in
orbit determination algorithms to obtain more reliable asteroid trajectories.
